Crude oil recovery effect evaluation apparatus and crude oil recovery effect evaluation method

Abstract

To provide an evaluation apparatus and an evaluation method capable of accurately evaluating whether or not a crude oil recovery effect due to chemical osmosis in a low-salinity water flooding method can be obtained.SOLUTION: An evaluation apparatus 100 includes: an effective osmotic pressure ▵P measuring device 10; a device that calculates a crude oil movement amount ▵V on the basis of a measurement result selected from among a measurement result of calculating the ratio of crude oil amount and water amount in a test body per unit time, a measurement result of the crude oil amount exuded from the test body in contact with low-salinity water, and a measurement result of the mass difference of the test body before and after contact of the test body with low-salinity water; and an evaluation device 30 that determines that a crude oil recovery effect is present when a condition selected from among the effective osmotic pressure ▵P is greater than 0 and the effective osmotic pressure ▵P changes per unit time and no crude oil movement amount ▵V is confirmed, the effective osmotic pressure ▵P is greater than 0 and the effective osmotic pressure ▵P changes per unit time and the crude oil movement amount ▵V is confirmed, and the effective osmotic pressure ▵P is 0 and the crude oil movement amount ▵V is confirmed, is satisfied.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an apparatus for evaluating the crude oil recovery effect by a low salinity water flooding method and a method for evaluating the crude oil recovery effect.

Background Art

[0002] Crude oil in an oil reservoir contained in underground rock can be extracted by a primary recovery method that pushes the crude oil up to the test cone hole of the oil well by the pressure in the oil reservoir. However, in the primary recovery method, only a part of the crude oil existing in the oil reservoir can be extracted. For this reason, after crude oil is collected using the primary recovery method, a secondary recovery method is performed in which water, gas, etc. are injected into the oil reservoir to restore the pressure in the oil reservoir and the crude oil is collected. By using the secondary recovery method, the crude oil recovery rate from the oil reservoir can be increased and the oil production volume can be increased.

[0003] However, a large amount of crude oil still remains in the oil reservoir collected using the secondary recovery method. Therefore, it is required to recover crude oil from the oil reservoir collected using the secondary recovery method and further increase the oil production volume.

[0004] The tertiary recovery method for recovering the crude oil remaining in the oil reservoir collected using the secondary recovery method is called an enhanced oil recovery (EOR). As enhanced oil recovery methods, there are various methods such as chemical flooding, thermal flooding, gas injection flooding, microbial flooding, and low salinity water flooding (LSWF).

[0005] Among these enhanced oil recovery methods, the low salinity water flooding method is attracting attention because it has a wide application range and less environmental impact. The low salinity water flooding method is a method of recovering the crude oil remaining in the oil reservoir by injecting salt-containing water having a lower salinity than the salt water contained in the oil reservoir or water not containing salt into the oil reservoir.

[0006] Non-Patent Document 1 describes the proposed recovery mechanism for the low-salinity water flooding method. In addition, Non-Patent Documents 2 and 3 describe experimental evidence of enhanced oil recovery due to chemical osmosis in the low-salinity water flooding method.

Prior Art Documents

Non-Patent Documents

[0007]

Non-Patent Document 1

Non-Patent Document 2

Non-Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0008] However, even when using the low-salinity water flooding method to recover the crude oil remaining in the oil reservoir, the expected effect may not be obtained. Therefore, before performing the low-salinity water flooding method on the oil reservoir, the crude oil recovery effect by the low-salinity water flooding method is evaluated using test specimens collected from the oil reservoir targeted for crude oil recovery.

[0009] However, in the conventional techniques for evaluating the crude oil recovery effect, it has not been possible to determine whether the crude oil remaining in the oil reservoir layer moves by chemical osmosis. For this reason, it has not been possible to accurately evaluate the crude oil recovery effect caused by chemical osmosis in the low-salinity water flooding method for a test body made of rock collected from an oil reservoir layer.

[0010] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an apparatus for evaluating a crude oil recovery effect and a method for evaluating a crude oil recovery effect that can accurately evaluate whether a crude oil recovery effect caused by chemical osmosis in a low-salinity water flooding method can be obtained for a test body made of rock.

Means for Solving the Problems

[0011] [1] An effective osmotic pressure ΔP measuring device that measures the pressure of the high-salinity water and the pressure of the low-salinity water per unit time in a test body made of rock containing high-salinity water and crude oil with a first salt concentration and in contact with low-salinity water having a second salt concentration lower than the first salt concentration, and calculates the effective osmotic pressure ΔP, which is the pressure difference between the high-salinity water and the low-salinity water, per unit time, An apparatus for calculating the amount of crude oil movement ΔV generated by the salt concentration difference ΔC between the first salt concentration and the second salt concentration, and calculating the amount of crude oil movement ΔV based on any one or two or more of the following measurement results (1) to (3). An apparatus for measuring the amount of crude oil movement ΔV An evaluation apparatus for evaluating the presence or absence of a crude oil recovery effect, which determines that there is a crude oil recovery effect caused by chemical osmosis in the low-salinity water flooding method for the test body when any one or two or more of the following conditions (i) to (iii) are satisfied. An evaluation apparatus for a crude oil recovery effect including

[0012] (1) Measurement results of calculating the ratio of the amount of crude oil and the amount of water in the test body per unit time. (2) Measurement results of the amount of crude oil exuded from the test body in contact with the low-salinity water. (3) Measurement results of the mass difference of the test specimen before bringing the test specimen into contact with the low-salt-concentration water and after bringing the test specimen into contact with the low-salt-concentration water.

[0013] (i) The effective osmotic pressure △P is greater than 0, the effective osmotic pressure △P changes per unit time, and the presence of the crude oil movement amount △V cannot be confirmed. (ii) The effective osmotic pressure △P is greater than 0, the effective osmotic pressure △P changes per unit time, and the presence of the crude oil movement amount △V can be confirmed. (iii) The effective osmotic pressure △P is 0, and the presence of the crude oil movement amount △V can be confirmed.

[0014] [2] The crude oil movement amount △V measuring device includes an X-ray CT measuring device that measures the X-ray CT value of the test specimen per unit time and / or a specific resistance measuring device that measures the specific resistance value of the test specimen per unit time, and based on the X-ray CT value measured per unit time of the test specimen and / or the specific resistance value measured per unit time of the test specimen, the evaluation device for the crude oil recovery effect according to [1], which has a crude oil movement amount △V calculation device that calculates the ratio of the amount of crude oil and the amount of moisture in the test specimen per unit time.

[0015] [3] The crude oil movement amount △V measuring device calculates the crude oil movement amount △V based on the measurement result of (1), and the evaluation device for the crude oil recovery effect according to [1]. [4] The test specimen is in contact with the low-salt-concentration water by contacting the rock containing the low-salt-concentration water, and the evaluation device for the crude oil recovery effect according to [1].

[0016] [5] The test specimen is composed of a rock collected from an oil reservoir layer for which the crude oil recovery effect is to be evaluated or a rock simulating the oil reservoir layer, It has a container for accommodating the test specimen, A pressurizing device that applies a confinement pressure simulating the formation pressure of the oil reservoir layer to the test specimen accommodated in the container, A heating device that heats the test specimen accommodated in the container to a temperature simulating the formation temperature of the oil reservoir layer, The evaluation device for crude oil recovery effect according to [1], comprising any one or two or more devices selected from a hydraulic loading device that loads a pore water pressure simulating the pore water pressure in the oil storage layer onto the test body accommodated in the container.

[0017] [6] A first step of measuring, per unit time, the pressure of the high-salt concentration water and the pressure of the low-salt concentration water in a test body composed of rock containing high-salt concentration water and crude oil of a first salt concentration and in contact with low-salt concentration water having a second salt concentration lower than the first salt concentration, and calculating, per unit time, an effective osmotic pressure ΔP which is the pressure difference between the high-salt concentration water and the low-salt concentration water. A step of calculating an amount of crude oil movement ΔV generated by a salt concentration difference ΔC between the first salt concentration and the second salt concentration, the second step of calculating the amount of crude oil movement ΔV based on any one or two or more measurement results selected from the following (1) to (3). A step of evaluating the presence or absence of a crude oil recovery effect, the third step of determining that there is a crude oil recovery effect due to chemical osmosis in the low-salt concentration water flooding method for the test body when any one or two or more conditions selected from the following (i) to (iii) are satisfied. The evaluation method of the crude oil recovery effect includes this.

[0018] (1) Measurement results of calculating, per unit time, the ratio of the amount of crude oil and the amount of water in the test body. (2) Measurement results of the amount of crude oil exuded from the test body in contact with the low-salt concentration water. (3) Measurement results of the mass difference of the test body before bringing the test body into contact with the low-salt concentration water and after bringing the test body into contact with the low-salt concentration water.

[0019] (i) The effective osmotic pressure ΔP is greater than 0, the effective osmotic pressure ΔP changes per unit time, and the presence of the amount of crude oil movement ΔV cannot be confirmed. (ii) The effective osmotic pressure ΔP is greater than 0, the effective osmotic pressure ΔP changes per unit time, and the presence of the amount of crude oil movement ΔV can be confirmed. (iii) The effective osmotic pressure ΔP is 0, and the presence of the amount of crude oil movement ΔV can be confirmed.

[0020] [7] In the second step, the X-ray CT value of the test specimen is measured per unit time by an X-ray CT measuring device and / or the specific resistance value of the test specimen is measured per unit time by a specific resistance measuring device, and based on the X-ray CT value measured per unit time of the test specimen and / or the specific resistance value measured per unit time of the test specimen, the ratio of the amount of crude oil and the amount of moisture in the test specimen is calculated per unit time. The method for evaluating the crude oil recovery effect according to [6].

[0021] [8] In the second step, based on the measurement result of (1), the amount of crude oil movement ΔV is calculated. The method for evaluating the crude oil recovery effect according to [6]. [9] The method for evaluating the crude oil recovery effect according to [6], wherein the test specimen is in contact with the low-salt concentration water by contacting the rock containing the low-salt concentration water.

[0022]

[10] The test specimen is composed of a rock collected from an oil reservoir layer for which the crude oil recovery effect is to be evaluated, or a rock simulating the oil reservoir layer, and is accommodated in a container in a state satisfying any one or two or more of the following conditions (a) to (c). The method for evaluating the crude oil recovery effect according to [6]. (a) A state in which a confining pressure simulating the formation pressure of the oil reservoir layer is applied. (b) A state in which the temperature is heated to a temperature simulating the formation temperature of the oil reservoir layer. (c) A state in which an interstitial water pressure simulating the interstitial water pressure in the oil reservoir layer is applied. [Effect of the Invention]

[0023] By using the apparatus for evaluating the crude oil recovery effect and the method for evaluating the crude oil recovery effect of the present invention, it is possible to accurately evaluate whether or not a crude oil recovery effect due to chemical osmosis in the low-salt concentration water flooding method can be obtained for a test specimen made of rock. Therefore, according to the present invention, for example, by using a rock collected from an oil reservoir layer that is the target of crude oil recovery as a test specimen, it is possible to accurately evaluate whether or not a crude oil recovery effect can be obtained when the crude oil remaining in the oil reservoir layer is recovered by the low-salt concentration water flooding method.

Brief Description of the Drawings

[0024]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Mode for Carrying Out the Invention

[0025] The present inventors focused on the enhanced recovery mechanism of the low-salinity water flooding method in order to solve the above problems and accurately evaluate the crude oil recovery effect caused by chemical osmosis in the low-salinity water flooding method for a test body made of rock collected from an oil reservoir layer that is the target of crude oil recovery, and conducted intensive studies as follows.

[0026] When a test body made of rock containing high-salinity water and crude oil is placed in contact with low-salinity water, an effective osmotic pressure ΔP, which is the pressure difference between the high-salinity water and the low-salinity water, may occur. Chemical osmosis is the movement of water from low-salinity water to high-salinity water that occurs using the chemical potential as the driving force. Chemical osmosis occurs through semi-permeable membranes such as clay minerals contained in the rock forming the test body, water films existing at the boundary between the crude oil and the clay minerals, and the crude oil itself.

[0027] In chemical osmosis, water is allowed to penetrate from low-salinity water through a semi-permeable membrane into the interior of a rock containing high-salinity water and crude oil as the test specimen, generating an effective osmotic pressure ΔP in the high-salinity water. Also, the effective osmotic pressure ΔP generated in the high-salinity water causes a pressure-driven flow of the mixture of crude oil and interstitial water from the high-salinity water to the low-salinity water. As a result, a mixture of crude oil and interstitial water with the same volume as the water that has penetrated into the rock by chemical osmosis exudes from the end face of the rock in contact with the low-salinity water.

[0028] From these facts, the inventor considered that for a test specimen made of rock, when the effective osmotic pressure ΔP shown below is greater than 0, it can be evaluated that a crude oil recovery effect by chemical osmosis can be obtained in the low-salinity water injection method. That is, a test specimen made of rock containing high-salinity water and crude oil is placed in contact with low-salinity water, and when the effective osmotic pressure ΔP generated by the chemical potential difference between the high-salinity water and the low-salinity water is greater than 0, a pressure-driven flow of the mixture of crude oil and interstitial water from the high-salinity water to the low-salinity water occurs with the effective osmotic pressure ΔP as the driving force. Thereby, it was considered that crude oil can be exuded from the rock forming the test specimen into the low-salinity water, and it can be evaluated that a crude oil recovery effect by chemical osmosis can be obtained in the low-salinity water injection method.

[0029] However, as a result of the inventor's examination of the crude oil recovery effect by chemical osmosis in the low-salinity water injection method, it was found that even when the effective osmotic pressure ΔP is greater than 0, the crude oil recovery effect may not continue. More specifically, the exudation of the mixture of crude oil and interstitial water from inside the rock due to chemosmosis does not occur uniformly from inside the rock. Inside the rock, voids of various sizes are connected, and each void has a viscous resistance and a threshold pressure Pth (capillary pressure) corresponding to its size. The threshold pressure Pth is larger for smaller-sized voids. For this reason, the mixture of crude oil and interstitial water present inside the rock preferentially moves through voids with low viscous resistance and threshold pressure Pth, that is, through a void network connected by larger-sized voids, and is carried out to the outside of the specimen.

[0030] Also, the void network through which the mixture of crude oil and interstitial water preferentially moves is also composed of voids of various sizes, and the viscous resistance and threshold pressure Pth are not uniform. When the moving mixture of crude oil and interstitial water (more precisely, the interface between crude oil and interstitial water) passes through a void with a large threshold pressure Pth (a small-sized void), a large driving force (a large effective osmotic pressure △P) is required. For this reason, when the mixture of crude oil and interstitial water attempts to pass through a small-sized void, the movement of the mixture of crude oil and interstitial water temporarily stops. On the other hand, in the semipermeable membrane in the rock, chemosmosis from low-salinity water to high-salinity water occurs even while the movement of the mixture of crude oil and interstitial water has stopped, and the effective osmotic pressure △P increases. And when the effective osmotic pressure △P exceeds the threshold pressure Pth of the small voids that had been hindering the movement of the mixture of crude oil and interstitial water, the mixture of crude oil and interstitial water passes through the small voids. That is, the mixture of crude oil and interstitial water starts moving again, and the once-increased effective osmotic pressure △P decreases back to the original value corresponding to the viscous resistance of the voids.

[0031] Thus, while crude oil is exuding from the rock by chemosmosis through the semipermeable membrane, the effective osmotic pressure ΔP repeatedly increases and decreases in accordance with the viscous resistance of the pores through which the mixture of crude oil and interstitial water attempts to pass and the threshold pressure Pth. However, the crude oil present in pores (pores with a small size) having a large threshold pressure Pth that exceeds the driving force by the effective osmotic pressure ΔP that repeatedly increases and decreases does not move even while chemosmosis is occurring and remains inside the rock.

[0032] From these facts, even after the crude oil recovery effect from the specimen due to chemosmosis has disappeared, there may be cases where crude oil remains inside the rock forming the specimen. In this case, within the specimen, since chemosmosis continues to occur through semipermeable membranes such as clay minerals contained in the rock, the water film existing at the boundary between the clay minerals and the crude oil, and the remaining crude oil itself, the effective osmotic pressure ΔP becomes greater than 0. However, a crude oil recovery effect cannot be obtained.

[0033] In a state where chemosmosis that does not cause such a crude oil recovery effect continues to occur, no crude oil is taken out from the rock forming the specimen to the outside. For this reason, no change in the amount of crude oil in the specimen is observed over time. Also, the value of the effective osmotic pressure ΔP generated by chemosmosis does not change over time, and the effective osmotic pressure ΔP becomes a value slightly greater than 0 and is approximately constant.

[0034] On the other hand, when the effective osmotic pressure ΔP is greater than 0 and the effective osmotic pressure ΔP repeatedly increases and decreases (in other words, changes) over time, it can be considered that crude oil is exuding from the rock forming the specimen into low-salt-concentration water, and it can be evaluated that a crude oil recovery effect by chemosmosis is obtained in the low-salt-concentration water flooding method.

[0035] In addition, the present inventor focused on the size of voids in a test specimen made of rock and repeatedly examined the crude oil recovery effect by chemical osmosis in a low-salt concentration water flooding method for the test specimen. As a result, it was found that when the test specimen is a rock having relatively large voids (for example, voids with a shortest distance between opposing wall surfaces of 1 μm or more), although chemical osmosis occurs inside the test specimen due to the salt concentration difference ΔC, the effective osmotic pressure ΔP may become zero.

[0036] This is because the effective osmotic pressure ΔP is expressed according to the viscous resistance corresponding to the size of the voids and the threshold pressure Pth, and the larger the voids, the lower the effective osmotic pressure ΔP at which pressure flow of the mixture of crude oil and water occurs. More specifically, inside the test specimen, although a local internal effective osmotic pressure is generated according to the size of the voids, since the viscous resistance is small, the mixture of crude oil and water immediately moves and the local internal effective osmotic pressure dissipates. As a result, it is presumed that the effective osmotic pressure ΔP, which is the pressure difference between the high-salt concentration water present near the outer surface of the test specimen or the high-salt concentration water taken out from the test specimen to the outside, and the low-salt concentration water present near the outer surface of the test specimen or the low-salt concentration water taken out from the test specimen to the outside, may also be less than the detection limit of the pressure measuring device.

[0037] Therefore, the present inventor repeatedly examined to evaluate whether a crude oil recovery effect due to chemical osmosis in a low-salt concentration water flooding method can be obtained even when the effective osmotic pressure ΔP becomes zero in a state where a test specimen made of rock containing high-salt concentration water and crude oil is brought into contact with low-salt concentration water. As a result, it was found that even when the effective osmotic pressure ΔP becomes zero, it is possible to detect whether chemical osmosis is occurring based on the following crude oil movement amount ΔV.

[0038] The crude oil movement amount ΔV is the crude oil movement amount ΔV resulting from chemical osmosis generated by the salt concentration difference ΔC. The crude oil movement amount ΔV is calculated based on any one or two or more measurement results selected from the following (1) to (3). (1) A measurement result obtained by calculating the ratio of the amount of crude oil and the amount of water in the test specimen per unit time. (2) Measurement results of the amount of crude oil exuded from the test specimen in contact with the low-salt-concentration water. (3) Measurement results of the mass difference of the test specimen before bringing the test specimen into contact with the low-salt-concentration water and after bringing the test specimen into contact with the low-salt-concentration water.

[0039] If the existence of the crude oil movement amount ΔV can be confirmed, even when the effective osmotic pressure ΔP is 0, it can be said that there is a crude oil recovery effect due to chemical osmosis in the low-salt-concentration water flooding method. Also, it can be said that the higher the crude oil movement amount ΔV, the higher the crude oil recovery effect due to chemical osmosis in the low-salt-concentration water flooding method.

[0040] In addition, when the test specimen is a rock having relatively small voids (for example, voids with a shortest distance between opposing wall surfaces of less than 1 μm), since the crude oil movement amount ΔV is small, it may not be possible to measure the crude oil movement amount ΔV, or the measurement error of the crude oil movement amount ΔV may increase. Therefore, it is difficult to evaluate with sufficient accuracy whether a crude oil recovery effect by the low-salt-concentration water flooding method can be obtained using the crude oil movement amount ΔV. However, when the test specimen is a rock having relatively small voids, when the effective osmotic pressure ΔP is 0, no crude oil recovery effect due to chemical osmosis in the low-salt-concentration water flooding method can be obtained.

[0041] From these facts, the present inventors have earnestly studied to develop a method capable of highly accurately evaluating whether a crude oil recovery effect due to chemical osmosis can be obtained in the low-salt-concentration water flooding method, regardless of whether the rock as the test specimen has large or small voids.

[0042] As a result, for a test specimen composed of a rock containing high-salt-concentration water and crude oil collected from an oil reservoir layer that is the target of crude oil recovery, based on the result of calculating the above effective osmotic pressure ΔP per unit time in a state of being in contact with low-salt-concentration water and the above crude oil movement amount ΔV, when any one or two or more conditions selected from the following (i) to (iii) are satisfied, it was found that it is sufficient to determine that there is a crude oil recovery effect due to chemical osmosis in the low-salt-concentration water flooding method for the test specimen, and the present invention was conceived.

[0043] (i) The effective osmotic pressure ΔP is greater than 0, the effective osmotic pressure ΔP changes per unit time, and the presence of the crude oil movement amount ΔV cannot be confirmed. (ii) The effective osmotic pressure ΔP is greater than 0, the effective osmotic pressure ΔP changes per unit time, and the presence of the crude oil movement amount ΔV can be confirmed. (iii) The effective osmotic pressure ΔP is 0, and the presence of the crude oil movement amount ΔV can be confirmed.

[0044] Hereinafter, the evaluation apparatus for the crude oil recovery effect and the evaluation method for the crude oil recovery effect of the present invention will be described in detail with reference to the drawings. Note that the drawings used in the following description may show, for the sake of clarity, the characteristic parts enlarged for convenience. For this reason, the dimensional ratios of the respective components may be different from the actual ones. The scope of the present invention is not limited to the embodiment described herein, and various modifications can be made without departing from the spirit of the present invention. Also, when a plurality of upper limit values and lower limit values are described for a specific parameter, any upper limit value and lower limit value can be combined to form a suitable numerical range.

[0045] <First Embodiment> [Apparatus for Evaluating Crude Oil Recovery Effect] FIG. 1 is a schematic diagram for explaining an apparatus for evaluating the crude oil recovery effect caused by chemical osmosis in the low salinity water injection method of the first embodiment. In the evaluation apparatus 100 of the present embodiment, a test body 1 made of rock containing high salinity water 11c and crude oil is used as an evaluation object. The test body 1 is a rock for which it is desired to evaluate the crude oil recovery effect caused by chemical osmosis in the low salinity water injection method, and it is preferably a rock collected from an oil reservoir that is the target of crude oil recovery. The test body 1 may be a rock simulating an oil reservoir that is the target of crude oil recovery.

[0046] As shown in Fig. 1, Test Specimen 1 preferably contains high-salinity water 11c which is interstitial water in the oil reservoir layer. When Test Specimen 1 is a rock simulating the oil reservoir layer targeted for crude oil recovery, Test Specimen 1 may contain salt-concentration water prepared using sodium chloride or the like instead of high-salinity water 11c which is interstitial water in the oil reservoir layer, and having the same amount of dissolved substances as the interstitial water in the oil reservoir layer.

[0047] In addition, the crude oil targeted for recovery in Test Specimen 1 is preferably the crude oil contained in the rock for which the crude oil recovery effect is to be evaluated, but it may also be an oil simulating the crude oil impregnated in Test Specimen 1. Examples of the oil simulating crude oil include liquid paraffin, toluene, and the like. The type of rock that Test Specimen 1 is made of is not particularly limited, and examples include shale, sandstone, carbonate rock, and the like.

[0048] Test Specimen 1 shown in Fig. 1 has a substantially cylindrical shape. In the present embodiment, Test Specimen 1 is sealed by a coating sheet 16 covering the entire side surface of Test Specimen 1 and end caps 15 respectively disposed on both end faces of Test Specimen 1. The coating sheet 16 is made of a flexible sheet having water resistance, chemical resistance, and oil resistance, such as a rubber sheet made of fluororubber. As the end cap 15, for example, one made of a resin such as polyetheretherketone (PEEK) can be used. The end cap 15 is substantially circular in plan view. The end cap 15 may be provided with a plurality of grooves for diffusing high-salinity water 11c or low-salinity water 12c in the diameter direction of Test Specimen 1 on the surface on the side of Test Specimen 1.

[0049] As shown in FIG. 1, a water distribution plate 14 having a substantially circular shape in plan view is disposed between the end cap 15 and the test specimen 1. The water distribution plate 14 stores high-salt-concentration water 11c or low-salt-concentration water 12c, and contacts the end face of the test specimen 1 facing the water distribution plate 14 with the high-salt-concentration water 11c or the low-salt-concentration water 12c uniformly in the diameter direction of the test specimen 1 without applying pressure. In the present embodiment, due to the installation of the water distribution plate 14, the high-salt-concentration water 11c or the low-salt-concentration water 12c diffuses uniformly from the end face of the test specimen 1 and is not forcibly injected from the end face of the test specimen 1. As the water distribution plate 14, for example, a porous resin plate made of a resin such as polyetheretherketone (PEEK) can be preferably used.

[0050] In the present embodiment, instead of the water distribution plate 14, an end cap 15 having a function as a water distribution plate and also serving as a water distribution plate may be used. Examples of such an end cap 15 include those provided with a plurality of grooves or the like for diffusing the high-salt-concentration water 11c or the low-salt-concentration water 12c in the diameter direction of the test specimen 1 on the surface on the test specimen 1 side and bringing it into contact with the test specimen 1.

[0051] As shown in FIG. 1, between both ends of the test specimen 1 and the water distribution plate 14, current electrodes 22a and 22b of the specific resistance measuring device 22 are disposed in contact with the end face of the test specimen 1. As the current electrodes 22a and 22b, for example, those made of a substantially circular metal mesh in plan view can be used.

[0052] As shown in FIG. 1, the evaluation apparatus 100 for the crude oil recovery effect of the present embodiment includes a container 13 that houses the test specimen 1, a pressure measuring device 33 that measures the pressures of the high-salt-concentration water 11c and the low-salt-concentration water 12c, a salt concentration measuring device 32 that measures the salt concentrations of the high-salt-concentration water 11c and the low-salt-concentration water 12c, an effective osmotic pressure ΔP measuring device 10 having these, an X-ray CT measuring device 21, a specific resistance measuring device 22, a crude oil movement amount ΔV measuring device (not shown) having a crude oil movement amount ΔV calculation device (not shown), and an evaluation device 30.

[0053] As the container 13 shown in Fig. 1, it is preferably made of a material that can transmit the X-rays irradiated from the X-ray irradiation device 21a to the test body 1, can obtain sufficient pressure resistance when a confinement pressure is applied to the test body 1, and can obtain sufficient heat resistance when the test body 1 is heated to a temperature simulating the ground temperature of the oil storage layer. Specifically, as the container 13, one made of a resin such as polyetheretherketone (PEEK) and having a sufficient thickness can be preferably used.

[0054] The shape of the container 13 can be, for example, cylindrical as shown in Fig. 1, and as long as it can accommodate the test body 1 provided with the current electrodes 22a, 22b and the potential electrode 22c, and the water separation plates 14 arranged at both ends thereof, in a sealed state by the coating sheets 16 and the two end caps 15, it is not particularly limited.

[0055] The evaluation apparatus 100 for the crude oil recovery effect of the present embodiment preferably includes a pressurizing device (not shown) for applying a confinement pressure simulating the formation pressure of the oil storage layer to the test body 1 accommodated in the container 13, a heating device 18 for heating the test body 1 accommodated in the container 13 to a temperature simulating the ground temperature of the oil storage layer, and a water pressure loading device (not shown) for applying an interstitial water pressure simulating the interstitial water pressure in the oil storage layer to the test body 1 accommodated in the container 13. The reason is that by setting the test body 1 to have a confinement pressure, temperature, and interstitial water pressure simulating the oil storage layer that is the target of crude oil recovery, the test body 1 can be evaluated under conditions that more closely match the state existing in the oil storage layer. As a result, by using the evaluation apparatus 100 of the present embodiment, the crude oil recovery effect caused by chemical osmosis in the low-salt concentration water flooding method for the test body 1 can be evaluated with high accuracy under conditions closer to reality.

[0056] When the confinement pressure applied to the specimen 1 housed in the container 13 is increased, the voids of the clay minerals become smaller and the semi-permeable membrane property increases. As a result, the amount of chemical osmosis increases and the effective osmotic pressure △P tends to increase. In the present embodiment, it is preferable to apply a confinement pressure simulating the formation pressure of the oil reservoir layer to the specimen 1 housed in the container 13 by a pressurizing device so that the confinement pressure applied to the specimen 1 is as high as that of the oil reservoir layer. As the pressurizing device, any device that can apply a sufficient confinement pressure simulating the formation pressure of the oil reservoir layer to the specimen 1 housed in the container 13 may be used, and a known device that can pressurize the inside of the container 13 can be used.

[0057] When the temperature of the specimen 1 housed in the container 13 is increased, the viscosity of the crude oil decreases and the viscous resistance of the voids through which the mixed liquid of the crude oil and the interstitial water attempts to pass also decreases. For this reason, the exudation of the crude oil from the small voids becomes easy, and the movement of the mixed liquid of the crude oil and water inside the specimen 1 tends to become easy. In the present embodiment, it is preferable to heat the specimen 1 housed in the container 13 by the heating device 18 so that the specimen 1 has a temperature simulating the formation temperature of the oil reservoir layer.

[0058] As the heating device 18, any device that can heat the specimen 1 housed in the container 13 to a temperature simulating the formation temperature of the oil reservoir layer may be used. For example, as shown in FIG. 1, a known heater such as a sheet-shaped heater arranged to cover the outer periphery of the cylindrical container 13 can be used. As the sheet-shaped heater, for example, a carbon heat heater, a resin sheet heater, etc. can be used.

[0059] As shown in FIG. 1, the heating device 18 may be arranged along the outer surface of the container 13 or may be installed inside the container 13. The heating device 18 is preferably arranged so as to be able to transmit the X-rays irradiated from the X-ray irradiation device 21a, which will be described later, to the specimen 1 and / or is made of a material that can transmit X-rays.

[0060] When the pore water pressure of the specimen 1 accommodated in the container 13 is increased, molecular diffusion (the true nature of chemical osmosis) becomes intense, so the amount of chemical osmosis tends to increase. Also, crude oil and pore water are strictly speaking compressible fluids, and under high pore water pressure, the effective osmotic pressure ΔP for the same amount of chemical osmosis tends to be greater than that under low pore water pressure. In the present embodiment, it is preferable to load the specimen 1 accommodated in the container 13 with a pore water pressure simulating the pore water pressure in the oil reservoir layer by means of a water pressure loading device, so that the pore water pressure of the specimen 1 is as high as that of the pore water pressure in the oil reservoir layer.

[0061] As the water pressure loading device, any device that can load the specimen 1 accommodated in the container 13 with a pore water pressure simulating the pore water pressure in the oil reservoir layer may be used. As the water pressure loading device, for example, a device that can load the specimen 1 with pore water pressure by supplying low-salt-concentration water 12c and / or high-salt-concentration water 11c to the specimen 1 at a predetermined pressure can be used, and a known device such as a device for pressurizing the inside of the low-salt-water storage tank 12 that stores the low-salt-concentration water 12c supplied to the specimen 1 or a device for pressurizing the inside of the high-salt-water storage tank 11 that stores the high-salt-concentration water 11c can be used.

[0062] In the present embodiment, the case where a pressurizing device, a heating device, and a water pressure loading device are provided will be described as an example, but the heating device and the water pressure loading device may not be provided.

[0063] (Effective osmotic pressure ΔP measuring device) As shown in FIG. 1, the effective osmotic pressure ΔP measuring device 10 in the crude oil recovery effect evaluation device 100 of the present embodiment includes a high-salt-water storage tank 11 that stores high-salt-concentration water 11c, a high-salt-water supply pipe 11a, a high-salt-water discharge pipe 11b, a low-salt-water storage tank 12 that stores low-salt-concentration water 12c, a low-salt-water supply pipe 12a, a low-salt-water discharge pipe 12b, a pressure measuring device 33, a salt concentration measuring device 32, and an effective osmotic pressure ΔP calculation device (not shown).

[0064] On one end side in the longitudinal direction of the test piece 1 (the left end side in FIG. 1), a high-salt water storage tank 11 containing high-salt concentration water 11c is arranged, and on the other end side (the right end side in FIG. 1), a low-salt water storage tank 12 containing low-salt concentration water 12c is arranged.

[0065] Connected to the high-salt water storage tank 11 are a high-salt water supply pipe 11a that supplies high-salt concentration water 11c to a water distribution plate 14 that contacts the end face of the test piece 1 through an end cap 15, and a high-salt water discharge pipe 11b that discharges high-salt concentration water 11c from the water distribution plate 14 that contacts the end face of the test piece 1 through the end cap 15.

[0066] As shown in FIG. 1, a pump 31 for supplying high-salt concentration water 11c to the water distribution plate 14 that contacts the end face of the test piece 1 is provided in the high-salt water supply pipe 11a. In this embodiment, the high-salt concentration water 11c is supplied to the water distribution plate 14 that contacts the end face of the test piece 1 at a substantially constant liquid supply rate by the pump 31, and the high-salt concentration water 11c in the high-salt water storage tank 11 and the high-salt concentration water 11c contained in the water distribution plate 14 that contacts the end face of the test piece 1 are circulated. The flow rate of the high-salt concentration water 11c supplied by the pump 31 is set to a flow rate at which the high-salt concentration water 11c is not forcibly injected against the end face of the test piece 1, and can be, for example, about 10 mL / min.

[0067] Connected to the low-salt water storage tank 12 are a low-salt water supply pipe 12a that supplies low-salt concentration water 12c to a water distribution plate 14 that contacts the end face of the test piece 1 through an end cap 15, and a low-salt water discharge pipe 12b that discharges low-salt concentration water 12c from the water distribution plate 14 that contacts the end face of the test piece 1 through the end cap 15.

[0068] As shown in FIG. 1, a pump 31 for supplying low-salt-concentration water 12c to a water distribution plate 14 in contact with the end face of the test body 1 is provided in the low-salt-water supply pipe 12a. In the present embodiment, the pump 31 supplies the low-salt-concentration water 12c to the water distribution plate 14 in contact with the end face of the test body 1 at a substantially constant liquid feeding rate, and the low-salt-concentration water 12c in the low-salt-water storage tank 12 and the low-salt-concentration water 12c in contact with the water distribution plate 14 in contact with the end face of the test body 1 are circulated. The flow rate of the low-salt-concentration water 12c supplied by the pump 31 is set to a flow rate at which the low-salt-concentration water 12c is not forcibly injected with respect to the end face of the test body 1, and can be, for example, about 10 mL / min.

[0069] In the present embodiment, the test body 1 made of a rock containing high-salt-concentration water 11c and crude oil is in contact with the low-salt-concentration water 12c supplied via the water distribution plate 14 and the low-salt-water supply pipe 12a at the end face on the other end (the right end in FIG. 1) side.

[0070] The high-salt-concentration water 11c has a first salt concentration. The salt concentration (first salt concentration) of the high-salt-concentration water 11c is preferably the same as the salt concentration of the interstitial water contained in the oil reservoir layer from which the test body 1 was collected. Therefore, it is preferable to use as it is the test body 1 collected from the oil reservoir layer. When the salt concentration of the high-salt-concentration water 11c is the same as the interstitial water contained in the oil reservoir layer from which the test body 1 was collected, the crude oil recovery effect due to chemical penetration in the low-salt-concentration water attack method on the test body 1 can be evaluated under more realistic conditions, and the crude oil recovery effect can be evaluated with higher accuracy.

[0071] In addition, the low-salinity water 12c has a second salinity concentration that is less than the first salinity concentration. The salinity concentration (second salinity concentration) of the low-salinity water 12c only needs to be less than the first salinity concentration, and it is preferably the same as the salinity concentration of low-salinity water that can be used or purified near the oil reservoir layer from which the test body 1 was collected. The reason is that when the crude oil remaining in the oil reservoir layer from which the test body 1 was collected is recovered by the low-salinity water flooding method using low-salinity water that can be used or purified near the oil reservoir layer, it can be evaluated under more consistent conditions, and the crude oil recovery effect due to chemical osmosis in the low-salinity water flooding method for the test body 1 can be evaluated under more realistic conditions. The low-salinity water 12c may be water that does not contain salt.

[0072] In addition, in the high-salinity water discharge pipe 11b, a pressure measuring device 33 for measuring the pressure of the high-salinity concentration water 11c moving in the high-salinity water discharge pipe 11b per unit time and a salinity concentration measuring device 32 for measuring the salinity concentration of the high-salinity concentration water 11c moving in the high-salinity water discharge pipe 11b per unit time are installed. In addition, in the low-salinity water discharge pipe 12b, a pressure measuring device 33 for measuring the pressure of the low-salinity concentration water 12c moving in the low-salinity water discharge pipe 12b per unit time and a salinity concentration measuring device 32 for measuring the salinity concentration of the low-salinity concentration water 12c moving in the low-salinity water discharge pipe 12b per unit time are installed.

[0073] The effective osmotic pressure △P is generated by arranging a test body 1 composed of high-salinity concentration water 11c and rock containing crude oil in contact with the low-salinity concentration water 12c, gradually increases from the first point in time when the test body 1 containing the high-salinity concentration water 11c is brought into contact with the low-salinity concentration water 12c to the second point in time, repeats increasing and decreasing from the second point in time to the third point in time, and becomes substantially constant after the third point in time.

[0074] In this embodiment, the frequency of measuring the pressure and salt concentration of the high-salt-concentration water 11c and the low-salt-concentration water 12c per unit time may be constant or may be changed as necessary. The frequency of measuring the pressure and salt concentration of the high-salt-concentration water 11c and the low-salt-concentration water 12c per unit time is preferably, for example, from every 2 seconds to every 10 minutes between the first time point when the effective osmotic pressure ΔP gradually increases and the second time point. Also, between the second time point when the effective osmotic pressure ΔP repeats increase and decrease and the third time point, it is preferably, for example, from every 30 minutes to every 1 hour.

[0075] The measurement of the pressure and salt concentration of the high-salt-concentration water 11c and the low-salt-concentration water 12c is preferably terminated after confirming that the effective osmotic pressure ΔP that has repeated increase and decrease since the second time point has become substantially constant (reached the third time point). That is, the measurement of the pressure and salt concentration of the high-salt-concentration water 11c and the low-salt-concentration water 12c is preferably continuously performed per unit time as long as the effective osmotic pressure ΔP continues to increase and decrease. This is because it is possible to predict whether the crude oil recovery effect due to chemical osmosis in the low-salt-concentration water flooding method is continuously obtained.

[0076] In the high-salt-concentration water 11c, the frequency of measuring the pressure and the frequency of measuring the salt concentration may be the same or different. Also, in the low-salt-concentration water 12c, the frequency of measuring the pressure and the frequency of measuring the salt concentration may be the same or different. Also, the frequency of measuring the pressure in the high-salt-concentration water 11c and the low-salt-concentration water 12c may be the same or different, and it is preferably the same. This is because it is possible to accurately predict whether the crude oil recovery effect due to chemical osmosis in the low-salt-concentration water flooding method is obtained based on the increase and decrease of the effective osmotic pressure ΔP.

[0077] As the pressure measurement device 33 for measuring the pressures of the high-salt-concentration water 11c and the low-salt-concentration water 12c, known pressure measurement devices such as a pressure sensor and a differential pressure sensor can be used. The pressure measurement device 33 for measuring the pressure of the high-salt-concentration water 11c and the pressure measurement device 33 for measuring the pressure of the low-salt-concentration water 12c may be the same or different. In the present embodiment, the pressures of the high-salt-concentration water 11c and the low-salt-concentration water 12c measured by the pressure measurement device 33 are input to an effective osmotic pressure ΔP calculation device (not shown).

[0078] The effective osmotic pressure ΔP calculation device calculates the effective osmotic pressure ΔP, which is the pressure difference between the high-salt-concentration water 11c and the low-salt-concentration water 12c, per unit time when signals of the pressure of the high-salt-concentration water 11c and the pressure of the low-salt-concentration water 12c measured by the pressure measurement device 33 are input. Thus, in the effective osmotic pressure ΔP measurement device 10 of the present embodiment, the effective osmotic pressure ΔP in the test body 1 made of rock containing the high-salt-concentration water 11c and crude oil and in contact with the low-salt-concentration water 12c is calculated per unit time. The effective osmotic pressure ΔP calculated by the effective osmotic pressure ΔP calculation device is input to the evaluation device 30.

[0079] Also, as the salt concentration measurement device 32 for the high-salt-concentration water 11c and the low-salt-concentration water 12c, known salt concentration measurement devices such as an electrical conductivity electrode can be used. In the present embodiment, the salt concentrations of the high-salt-concentration water 11c and the low-salt-concentration water 12c measured by the salt concentration measurement device are input to a salt concentration difference ΔC calculation device (not shown).

[0080] The salinity concentration difference ΔC calculation device calculates the salinity concentration difference ΔC between the high-salinity concentration water 11c and the low-salinity concentration water 12c per unit time when the signals of the salinity concentration of the high-salinity concentration water 11c and the signals of the salinity concentration of the low-salinity concentration water 12c measured by the salinity concentration measurement device 32 are input. Thereby, in the effective osmotic pressure ΔP measurement device 10 of the present embodiment, the salinity concentration difference ΔC is calculated per unit time. The salinity concentration difference ΔC calculated by the salinity concentration difference ΔC calculation device is input to the evaluation device 30.

[0081] The function of calculating the effective osmotic pressure ΔP, which is the pressure difference between the high-salinity concentration water 11c and the low-salinity concentration water 12c, per unit time in the effective osmotic pressure ΔP calculation device, and the function of calculating the salinity concentration difference ΔC per unit time in the salinity concentration difference ΔC calculation device are realized by, for example, the functions provided in the central processing unit of the computer.

[0082] (Crude oil movement amount ΔV measurement device) The crude oil movement amount ΔV measurement device in the evaluation device 100 for the crude oil recovery effect of the present embodiment is a device that calculates the crude oil movement amount ΔV caused by chemosmosis due to the salinity concentration difference ΔC between the salinity concentration of the high-salinity concentration water 11c (the first salinity concentration) and the salinity concentration of the low-salinity concentration water 12c (the second salinity concentration).

[0083] In the present embodiment, as an example, a case where the crude oil movement amount ΔV measurement device is a device that calculates the crude oil movement amount ΔV based on the measurement results of calculating the ratio of the amount of crude oil and the amount of water in the test body 1 per unit time will be described as an example. As shown in FIG. 1, the crude oil movement amount ΔV measurement device of the present embodiment has an X-ray CT measurement device 21, a specific resistance measurement device 22, and a crude oil movement amount ΔV calculation device (not shown). In the present embodiment, a case where the crude oil movement amount ΔV measurement device has the X-ray CT measurement device 21 and the specific resistance measurement device 22 will be described as an example, but it may have only one of the X-ray CT measurement device 21 and the specific resistance measurement device 22.

[0084] The X-ray CT measurement device 21 measures the X-ray CT value of the specimen 1 every unit time. As shown in FIG. 1, the X-ray CT measurement device 21 includes an X-ray irradiation device 21a, a detector 21b, and a CT value calculation device 21c. The X-ray irradiation device 21a rotates around the circumference of the cylindrical specimen 1 along the side surface of the specimen 1 accommodated in the container 13 in the circumferential direction, and irradiates the specimen 1 with X-rays while moving along the length direction of the specimen 1, as shown in FIG. 1 for example. The detector 21b is disposed opposite to the X-ray irradiation device 21a with the specimen 1 therebetween, and rotates around the circumference of the specimen 1 along the side surface of the cylindrical specimen 1 in the circumferential direction together with the X-ray irradiation device 21a, and detects the amount of X-rays transmitted through the specimen 1 while moving along the length direction of the specimen 1. The CT value calculation device 21c calculates the X-ray CT value corresponding to the density of the specimen 1 from the detection result detected by the detector 21b.

[0085] In this embodiment, the case where the X-ray irradiation device 21a and the detector 21b rotate around the circumference of the specimen 1 along the side surface of the specimen 1 accommodated in the container 13 in the circumferential direction and move along the length direction of the specimen 1 is taken as an example for description. However, the way of moving the X-ray irradiation device 21a and the detector 21b is not particularly limited as long as the X-ray CT value of the entire specimen 1 can be measured. For example, the X-ray irradiation device 21a may rotate along the length direction of the cylindrical specimen 1 accommodated in the container 13 and irradiate the specimen 1 with X-rays while moving along the diameter direction of the specimen 1. In this case, the detector 21b is disposed opposite to the X-ray irradiation device 21a with the specimen 1 therebetween, and rotates along the length direction of the cylindrical specimen 1 together with the X-ray irradiation device 21a and detects the amount of X-rays transmitted through the specimen 1 while moving along the diameter direction of the specimen 1.

[0086] In this embodiment, the X-ray CT value is measured every unit time by the X-ray CT measurement device 21 and input to the crude oil movement amount △V calculation device described later. The frequency of measuring the X-ray CT value of the specimen 1 can be, for example, every 5 minutes to every 1 hour, and may be constant or may be changed as needed. The measurement of the X-ray CT value of Specimen 1 preferably starts when Specimen 1 is brought into contact with low-salt-concentration water 12c and ends after confirming that no change is observed in the X-ray CT value. That is, the measurement of the X-ray CT value of Specimen 1 is preferably continuously performed every unit time as long as the X-ray CT value continues to increase or decrease.

[0087] As the X-ray CT measurement device 21, for example, a commercially available X-ray CT measurement device used for medical purposes or the like can be used. As the X-ray CT measurement device 21, a microfocus X-ray CT measurement device or the like may be used. When a microfocus X-ray CT measurement device is used, not only the X-ray CT value of Specimen 1 but also the movement of crude oil can be evaluated using an image with high resolution.

[0088] Further, as the X-ray CT measurement device 21, for example, a pedestal having a table on which Specimen 1 accommodated in the container 13 is rotatably placed, and an X-ray irradiation device 21a and a detector 21b that rotate around the periphery of Specimen 1 around an axis substantially perpendicular to the table and move in the vertical direction of the table may be used.

[0089] The specific resistance measurement device 22 measures the specific resistance value of Specimen 1 every unit time. The specific resistance measurement device 22 includes a pair of current electrodes 22a, 22b, a plurality of potential electrodes 22c (six in the example shown in FIG. 1), and a specific resistance calculation device 22d that calculates the specific resistance value from the potential difference between a pair of potential electrodes 22c.

[0090] The pair of current electrodes 22a, 22b is made of a substantially circular metal mesh or the like in plan view. As shown in FIG. 1, the pair of current electrodes 22a, 22b are respectively installed at both ends in the length direction of Specimen 1 and are installed to face each other so as to cover the end faces of Specimen 1. In this embodiment, for example, the case where the current electrodes 22a and 22b are installed to face each other so as to cover both end faces of the test piece 1 has been described as an example so that the resistivity value of the test piece 1 can be measured with high precision. However, the shape and installation position of the current electrodes 22a and 22b can be appropriately changed as needed. For example, the current electrodes 22a and 22b may be arranged on the outer peripheral surface near both ends of the test piece 1 and may be in the form of a wire wound along the outer surface of the test piece 1 in the circumferential direction of the test piece 1. In this case, even if the X-ray CT measuring device 21 irradiates the test piece 1 with X-rays from the length direction of the columnar test piece 1, the current electrodes 22a and 22b are less likely to affect the detection result of the X-ray dose transmitted through the test piece 1.

[0091] The plurality of potential electrodes 22c are arranged at substantially equal intervals in the length direction of the test piece 1 between the pair of current electrodes 22a and 22b, and are each wound along the outer surface of the test piece 1 in the circumferential direction of the test piece 1. The current electrodes 22a and 22b and the potential electrodes 22c of the resistivity measuring device 22 are arranged to penetrate the coating sheet 16 and contact the end face or side face of the test piece 1, and together with the test piece 1, are sealed by the coating sheet 16 and the two end caps 15.

[0092] In this embodiment, the resistivity value is measured by the resistivity measuring device 22 every unit time and input to the crude oil movement amount △V calculating device described later. The frequency of measuring the resistivity value of the test piece 1 can be, for example, every 5 minutes to 1 hour, and may be constant or may be changed as needed. The measurement of the resistivity value of the test piece 1 preferably starts when the test piece 1 is brought into contact with the low-salt concentration water 12c and ends after confirming that no change is seen in the resistivity value. That is, the measurement of the resistivity value of the test piece 1 is preferably continued every unit time as long as the resistivity value continues to increase or decrease.

[0093] As the resistivity measuring device 22, for example, a known device such as a commercially available impedance measuring device can be used.

[0094] The crude oil movement amount ΔV calculation device calculates the ratio of the crude oil amount and the water amount in the test body 1 per unit time based on the specific resistance value measured for the test body 1 every unit time and / or the X-ray CT value measured for the test body 1 every unit time, and calculates the crude oil movement amount ΔV. The crude oil movement amount ΔV calculation device calculates the ratio of the crude oil amount and the water amount in the test body 1 per unit time when the signal of the X-ray CT value of the test body 1 measured by the X-ray CT measurement device 21 and the signal of the specific resistance value of the test body 1 measured by the specific resistance measurement device 22 are input, and calculates the crude oil movement amount ΔV based on the result. The crude oil movement amount ΔV calculated by the crude oil movement amount ΔV calculation device is input to the evaluation device 30.

[0095] In this embodiment, the crude oil movement amount ΔV may be calculated based only on the specific resistance value measured for the test body 1 every unit time, or the crude oil movement amount ΔV may be calculated based only on the X-ray CT value measured for the test body 1 every unit time. The crude oil movement amount ΔV calculation device preferably calculates both the crude oil movement amount ΔV calculated based only on the specific resistance value measured for the test body 1 every unit time and the crude oil movement amount ΔV calculated based only on the X-ray CT value measured for the test body 1 every unit time, and inputs them to the evaluation device 30. This is because the evaluation device 30 can evaluate whether the crude oil recovery effect is obtained with higher accuracy.

[0096] As a method for calculating the ratio of the crude oil amount and the water amount in the test body 1 per unit time from the X-ray CT value of the test body 1, specifically, the following method is used. First, prepare a plurality of rocks of the same type as the test body 1. After completely saturating the voids existing inside each rock with water, inject crude oil into each rock at different pressures. By doing this, a plurality of calibration test bodies with different mixing ratios of water and crude oil are prepared. The mixing ratio of water and crude oil is calculated from the porosity of the calibration test body and the densities of water and crude oil based on the measurement results of the mass difference of the calibration test body before and after injecting water and crude oil.

[0097] The calibration test specimen may be manufactured using brine having a salt concentration equivalent to that of high-salinity water 11c instead of water. In this case, the crude oil recovery effect due to chemical osmosis in the low-salt concentration water flooding method for test specimen 1 can be evaluated more accurately.

[0098] Next, the X-ray CT values of the obtained calibration test specimens are measured in the same manner as the measurement of the X-ray CT value of test specimen 1. Using the results, a relational expression between the X-ray CT value, the ratio of the crude oil amount and the water amount is obtained. Using the relational expression thus obtained, the ratio of the crude oil amount and the water amount in test specimen 1 is calculated from the X-ray CT value of test specimen 1.

[0099] Also, as a method for calculating the ratio of the crude oil amount and the water amount in test specimen 1 per unit time from the specific resistance value of test specimen 1, specifically, the method shown below is used. The specific resistance values of the above calibration test specimens are measured in the same manner as the measurement of the specific resistance value of test specimen 1. Using the results, a relational expression between the specific resistance value, the ratio of the crude oil amount and the water amount is obtained. Using the relational expression thus obtained, the ratio of the crude oil amount and the water amount in test specimen 1 is calculated from the specific resistance value of test specimen 1.

[0100] Also, as a method for calculating the crude oil movement amount △V from the results of calculating the ratio of the crude oil amount and the water amount in test specimen 1 per unit time, specifically, the method shown below is used. For example, after bringing test specimen 1 into contact with low-salt concentration water 12c, from the ratio of the crude oil amount and the water amount calculated from the X-ray CT value obtained by the first measurement and the ratio of the crude oil amount and the water amount calculated from the X-ray CT value obtained by the measurement after a predetermined time, the amount of crude oil decreased with the passage of time is calculated, and the crude oil movement amount △V that has moved from the first measurement until the passage of the predetermined time is used.

[0101] Also, for example, after bringing the test specimen 1 into contact with the low-salt concentration water 12c, the ratio of the amount of crude oil to the amount of water calculated from the specific resistance value obtained by the first measurement and the ratio of the amount of crude oil to the amount of water calculated from the specific resistance value obtained by the measurement after a predetermined time are used to calculate the amount of crude oil that has decreased over time, and this is taken as the amount of crude oil movement ΔV that has moved from the time of the first measurement until a predetermined time has elapsed.

[0102] In the apparatus for calculating the amount of crude oil movement ΔV, the function of calculating the ratio of the amount of crude oil to the amount of water in the test specimen 1 per unit time and the function of calculating the amount of crude oil movement ΔV per unit time are realized by, for example, the functions provided in the central processing unit of a computer.

[0103] (Evaluation apparatus) The evaluation apparatus 30 evaluates the crude oil recovery effect due to chemical osmosis in the low-salt concentration water attack method on the test specimen 1 based on the effective osmotic pressure ΔP and the amount of crude oil movement ΔV. The evaluation apparatus 30 determines that there is a crude oil recovery effect due to chemical osmosis in the low-salt concentration water attack method on the test specimen 1 when any one or two or more of the following conditions (i) to (iii) are satisfied.

[0104] (i) The effective osmotic pressure ΔP is greater than 0, the effective osmotic pressure ΔP changes per unit time, and the presence of the amount of crude oil movement ΔV cannot be confirmed. (ii) The effective osmotic pressure ΔP is greater than 0, the effective osmotic pressure ΔP changes per unit time, and the presence of the amount of crude oil movement ΔV can be confirmed. (iii) The effective osmotic pressure ΔP is 0, and the presence of the amount of crude oil movement ΔV can be confirmed.

[0105] In the present embodiment, when the effective osmotic pressure ΔP is 0, it means that the effective osmotic pressure ΔP calculated by the effective osmotic pressure ΔP measuring device 10 from the pressure signal of the high-salt concentration water 11c and the pressure signal of the low-salt concentration water 12c measured by the pressure measuring device 33 is a value less than the resolution (below the detection limit) of the effective osmotic pressure ΔP measuring device 10.

[0106] (When satisfying (i) or (ii)) The effective osmotic pressure ΔP is the pressure difference between the high-salinity water 11c and the low-salinity water 12c, and is generated by the osmosis caused by the salinity concentration difference ΔC between the high-salinity water 11c and the low-salinity water 12c. Therefore, when the effective osmotic pressure ΔP is greater than 0, osmosis occurs due to the salinity concentration difference ΔC.

[0107] However, for example, even after the crude oil recovery effect due to osmosis with respect to the test body 1 disappears, there may be a case where crude oil that cannot be recovered by osmosis remains in the test body 1, and thus the crude oil recovery effect may not be obtained even though the effective osmotic pressure ΔP is greater than 0. In this embodiment, since it is determined that there is a crude oil recovery effect when (i) or (ii) is satisfied, a case where the crude oil recovery effect cannot be obtained even though the effective osmotic pressure ΔP is greater than 0 is not misjudged as having a crude oil recovery effect. Therefore, the crude oil recovery effect due to osmosis in the low-salinity water injection method for the test body 1 can be accurately evaluated.

[0108] Also, for example, when the test body 1 is a rock having relatively small voids, the amount of crude oil movement ΔV may not be measurable, or the measurement error of the amount of crude oil movement ΔV may be large, resulting in insufficient evaluation accuracy of whether the crude oil recovery effect can be obtained by the low-salinity water injection method. In this embodiment, since it is determined that there is a crude oil recovery effect when (i) or (ii) is satisfied, for example, even when the test body 1 is a rock having relatively small voids, the crude oil recovery effect due to osmosis in the low-salinity water injection method can be evaluated with high accuracy.

[0109] In this embodiment, examples of the rock having relatively small voids include shale, sandstone, etc. Examples of relatively small voids include voids where the shortest distance between opposing wall surfaces is less than 1 μm.

[0110] (When satisfying (iii)) For example, when the test specimen is a rock having relatively large voids, even though the effective osmotic pressure ΔP is 0 (less than the detection limit), chemoosmosis may occur due to the salt concentration difference ΔC, and an oil recovery effect may be obtained. In the present embodiment, since it is determined that there is an oil recovery effect when (iii) is satisfied, even when the effective osmotic pressure ΔP is 0, a case where an oil recovery effect is obtained is not erroneously determined as having no oil recovery effect. Therefore, the oil recovery effect caused by chemoosmosis in the low-salt concentration water injection method for the test specimen 1 can be accurately evaluated.

[0111] In the present embodiment, examples of the rock having relatively large voids include carbonate rocks and sandstones. Examples of the relatively large voids include voids in which the shortest distance between opposing wall surfaces is 1 μm or more.

[0112] The evaluation device 30 in the present embodiment calculates the crude oil movement amount ΔV based on the measurement result obtained by the crude oil movement amount ΔV measuring device calculating the ratio of the amount of crude oil and the amount of water in the test specimen 1 per unit time. It is preferable that the condition of (iii) above is a case where the effective osmotic pressure ΔP is 0 and the crude oil movement amount ΔV changes per unit time. This is because it is possible to predict whether the oil recovery effect caused by chemoosmosis in the low-salt concentration water injection method is continuously obtained, and the oil recovery effect can be evaluated more accurately.

[0113] In the evaluation apparatus 30 according to this embodiment, as the crude oil movement amount ΔV, it is preferable to use both the crude oil movement amount ΔV calculated based only on the specific resistance value measured for each unit time of the test body 1 and the crude oil movement amount ΔV calculated based only on the X-ray CT value measured for each unit time of the test body 1. Specifically, in the above (iii), when the presence of the crude oil movement amount ΔV can be confirmed, it is preferable that the presence of both the crude oil movement amount ΔV calculated based only on the specific resistance value measured for each unit time of the test body 1 and the crude oil movement amount ΔV calculated based only on the X-ray CT value measured for each unit time of the test body 1 can be confirmed. Further, when the crude oil movement amount ΔV changes every unit time, it is preferable that both the crude oil movement amount ΔV calculated based only on the specific resistance value measured for each unit time of the test body 1 and the crude oil movement amount ΔV calculated based only on the X-ray CT value measured for each unit time of the test body 1 change every unit time. This is because the crude oil recovery effect can be evaluated with higher accuracy.

[0114] In the evaluation apparatus 30 according to this embodiment, based on the salt concentration difference ΔC calculated every unit time by the salt concentration difference ΔC calculation device of the effective osmotic pressure ΔP measurement device 10, it is preferable that it can be confirmed that the effective osmotic pressure ΔP and the crude oil movement amount ΔV are caused by the salt concentration difference ΔC. This is because the crude oil recovery effect caused by chemical osmosis in the low-salt concentration water flooding method can be evaluated more accurately.

[0115] [Evaluation Method of Crude Oil Recovery Effect] Next, as an example of the evaluation method of the crude oil recovery effect by the low-salt concentration water flooding method of this embodiment, taking as an example the case of evaluating the crude oil recovery effect caused by chemical osmosis in the low-salt concentration water flooding method for the test body 1 using the evaluation apparatus 100 for the crude oil recovery effect shown in FIG. 1, an explanation will be given. The evaluation method of the crude oil recovery effect of this embodiment includes a first step of calculating the effective osmotic pressure ΔP every unit time, a second step of calculating the crude oil movement amount ΔV, and a third step of evaluating the presence or absence of the crude oil recovery effect.

[0116] (First Step) As shown in Fig. 1, a test piece 1 made of rock containing high-salinity water 11c and crude oil and having a substantially cylindrical shape is prepared. Next, current electrodes 22a and 22b of the resistivity measurement device 22 are respectively installed at both ends in the length direction of the test piece 1. Further, a plurality of potential electrodes 22c are wound around the test piece 1 at substantially equal intervals in the length direction between the pair of current electrodes 22a and 22b. By this, the current electrodes 22a and 22b and the potential electrodes 22c are installed on the test piece 1.

[0117] Thereafter, a coating sheet 16 is installed on the entire side surface of the test piece 1 on which the pair of current electrodes 22a and 22b and the plurality of potential electrodes 22c are installed. Further, a water separation plate 14 and an end cap 15 are arranged in this order outside the current electrodes 22a and 22b installed on both end faces of the test piece 1, and the test piece 1 on which the pair of current electrodes 22a and 22b and the plurality of potential electrodes 22c are installed is sealed by the coating sheet 16 and the end cap 15.

[0118] In the present embodiment, the case where the test piece 1 is made of rock collected from an oil reservoir layer for which the crude oil recovery effect is desired to be evaluated or rock simulating the oil reservoir layer and is accommodated in the container 13 in a state satisfying the following conditions (a) to (c) will be described as an example. (a) A state in which a confining pressure simulating the formation pressure of the oil reservoir layer is applied. (b) A state in which it is heated to a temperature simulating the formation temperature of the oil reservoir layer. (c) A state in which an interstitial water pressure simulating the interstitial water pressure in the oil reservoir layer is applied.

[0119] That is, the sealed test piece 1 is accommodated in the container 13, and the inside of the container 13 is pressurized by a pressurizing device (not shown) to apply a confining pressure simulating the formation pressure of the oil reservoir layer to the test piece 1, and the test piece 1 is heated from the outer surface of the container 13 by the heating device 18 to a temperature simulating the formation temperature of the oil reservoir layer.

[0120] Furthermore, as shown in FIG. 1, high-salt-concentration water 11c is stored in the high-salt-water storage tank 11 of the effective osmotic pressure △P measuring device 10. The inside of the high-salt-water storage tank 11 is pressurized by a water pressure loading device (not shown), and the high-salt-concentration water 11c is supplied to the test body 1 at a predetermined flow rate by the pump 31. Also, low-salt-concentration water 12c is stored in the low-salt-water storage tank 12. The inside of the low-salt-water storage tank 12 is pressurized by a water pressure loading device (not shown), and the low-salt-concentration water 12c is supplied to the test body 1 at a predetermined flow rate by the pump 31. By these means, an interstitial water pressure simulating the interstitial water pressure in the oil storage layer is loaded on the test body 1, and the same back pressure is applied to the high-salt-concentration water 11c contained in the water separation plate 14, the low-salt-concentration water 12c contained in the water separation plate 14, and the crude oil contained in the test body 1. Then, the loading of the interstitial water pressure on the high-salt-water storage tank 11 by the water pressure loading device (not shown) is stopped, and the high-salt-water storage tank 11 is sealed.

[0121] Thereafter, the high-salt-concentration water 11c is supplied from the high-salt-water storage tank 11 to the test body 1 at a substantially constant liquid delivery rate through the high-salt-water supply pipe 11a and the water separation plate 14 by the pump 31, and the high-salt-concentration water 11c is discharged from the high-salt-water discharge pipe 11b through the water separation plate 14. By this, the high-salt-concentration water 11c in the high-salt-water storage tank 11 and the high-salt-concentration water 11c contained in the water separation plate 14 in contact with the end face of the test body 1 are circulated.

[0122] Subsequently, the low-salt-concentration water 12c is supplied from the low-salt-water storage tank 12 to the test body 1 at a substantially constant liquid delivery rate through the low-salt-water supply pipe 12a and the water separation plate 14 by the pump 31, and the low-salt-concentration water 12c is discharged from the low-salt-water discharge pipe 12b through the water separation plate 14. By this, the low-salt-concentration water 12c is brought into contact with the end face on the other end (the right end in FIG. 1) side of the test body 1, and while keeping the interstitial water pressure at the end face on the other end side of the test body 1 constant, the low-salt-concentration water 12c in the low-salt-water storage tank 12 and the low-salt-concentration water 12c contained in the water separation plate 14 in contact with the end face of the test body 1 are circulated.

[0123] Then, the pressure measuring device 33 installed in the high-salt water discharge pipe 11b measures the pressure of the high-salt concentration water 11c moving in the high-salt water discharge pipe 11b every unit time. Also, the salt concentration measuring device 32 installed in the high-salt water discharge pipe 11b measures the salt concentration of the high-salt concentration water 11c moving in the high-salt water discharge pipe 11b every unit time.

[0124] Also, the pressure measuring device 33 installed in the low-salt water discharge pipe 12b measures the pressure of the low-salt concentration water 12c moving in the low-salt water discharge pipe 12b every unit time. Also, the salt concentration measuring device 32 installed in the low-salt water discharge pipe 12b measures the salt concentration of the low-salt concentration water 12c moving in the low-salt water discharge pipe 12b every unit time.

[0125] In the first step of this embodiment, the signals of the pressure of the high-salt concentration water 11c and the pressure of the low-salt concentration water 12c, respectively measured by the two pressure measuring devices 33, are input into the effective osmotic pressure ΔP calculation device, whereby the effective osmotic pressure ΔP, which is the pressure difference between the high-salt concentration water 11c and the low-salt concentration water 12c, is calculated every unit time. In the first step of this embodiment, it is preferable that the signals of the salt concentration of the high-salt concentration water 11c and the salt concentration of the low-salt concentration water 12c, respectively measured by the two salt concentration measuring devices 32, are input into the salt concentration difference ΔC calculation device, whereby the salt concentration difference ΔC between the high-salt concentration water 11c and the low-salt concentration water 12c is calculated every unit time.

[0126] (Second step) In this embodiment, the X-ray CT value of the specimen 1 is measured every unit time by the X-ray CT measuring device 21 and / or the specific resistance value of the specimen 1 is measured every unit time by the specific resistance measuring device 22.

[0127] The measurement of the X-ray CT value of the test specimen 1 can be performed, for example, by the method shown below. While rotating the X-ray irradiation device 21a circumferentially around the test specimen 1 along the side surface of the substantially cylindrical test specimen 1, the X-ray irradiation device 21a is moved along the length direction of the test specimen 1 to irradiate the test specimen 1 with X-rays. Further, together with the X-ray irradiation device 21a, the detector 21b is rotated circumferentially around the test specimen 1 along the side surface of the substantially cylindrical test specimen 1 and moved along the length direction of the test specimen 1 to detect the amount of X-rays transmitted through the test specimen 1. Then, the CT value calculation device 21c calculates the X-ray CT value corresponding to the density of the test specimen 1 from the detection result detected by the detector 21b.

[0128] The specific resistance value of the test specimen 1 can be measured, for example, by a method in which a current is applied from a pair of current electrodes 22a and 22b, the potential difference between a pair of potential electrodes 22c selected from a plurality of potential electrodes 22c is measured, and the specific resistance value is calculated by a specific resistance calculation device 22d from the result.

[0129] In the second step of the present embodiment, the signal of the X-ray CT value of the test specimen 1 measured by the X-ray CT measuring device 21 per unit time and the signal of the specific resistance value of the test specimen 1 measured by the specific resistance measuring device 22 per unit time are input to the crude oil movement amount △V measuring device. Then, based on the X-ray CT value measured for the test specimen 1 per unit time and / or the specific resistance value measured for the test specimen 1 per unit time by the crude oil movement amount △V measuring device, the ratio of the amount of crude oil and the amount of moisture in the test specimen 1 is calculated per unit time, and the crude oil movement amount △V is calculated based on the measurement result.

[0130] (Third step) In the third step of the present embodiment, the evaluation device 30 evaluates the presence or absence of the crude oil recovery effect. In the third step, when any one or two or more conditions selected from the following (i) to (iii) are satisfied, it is determined that there is a crude oil recovery effect due to chemical osmosis in the low-salt concentration water flooding method for the test specimen 1.

[0131] (i) The effective osmotic pressure △P is greater than 0, the effective osmotic pressure △P changes per unit time, and the presence of the crude oil movement amount △V cannot be confirmed. (ii) The effective osmotic pressure ΔP is greater than 0, the effective osmotic pressure ΔP changes per unit time, and the existence of the crude oil movement amount ΔV can be confirmed. (iii) The effective osmotic pressure ΔP is 0, and the existence of the crude oil movement amount ΔV can be confirmed.

[0132] The third step in this embodiment preferably satisfies the above conditions (ii) and / or (iii), and the crude oil movement amount ΔV changes per unit time. This is because it is possible to predict whether the crude oil recovery effect due to chemical osmosis in the low-salt concentration water flooding method continues to be obtained, and the crude oil recovery effect can be evaluated more accurately.

[0133] The evaluation device 100 for the crude oil recovery effect of this embodiment includes an effective osmotic pressure ΔP measuring device 10 that calculates the effective osmotic pressure ΔP per unit time, and a device that calculates the crude oil movement amount ΔV caused by chemical osmosis generated by the salt concentration difference ΔC. Based on the measurement results of calculating the ratio of the amount of crude oil and the amount of water in the test body 1 per unit time, it includes a crude oil movement amount ΔV measuring device that calculates the crude oil movement amount ΔV, and an evaluation device 30 that evaluates the presence or absence of the crude oil recovery effect. And when the evaluation device 30 satisfies any one or two or more of the above conditions (i) to (iii), it is determined that there is a crude oil recovery effect caused by chemical osmosis in the low-salt concentration water flooding method for the test body 1.

[0134] In addition, the evaluation method for the crude oil recovery effect of this embodiment includes a first step of calculating the effective osmotic pressure ΔP per unit time, a second step of calculating the crude oil movement amount ΔV based on the measurement results of calculating the ratio of the amount of crude oil and the amount of water in the test body 1 per unit time, and a third step of evaluating the presence or absence of the crude oil recovery effect. And when any one or two or more of the above conditions (i) to (iii) are satisfied in the third step, it is determined that there is a crude oil recovery effect caused by chemical osmosis in the low-salt concentration water flooding method for the test body 1.

[0135] Therefore, by using the evaluation apparatus 100 and the evaluation method of the crude oil recovery effect of the present embodiment, it is possible to accurately evaluate whether or not a crude oil recovery effect caused by chemical osmosis in the low-salt concentration water flooding method can be obtained for the test body 1 composed of rock containing high-salt concentration water and crude oil. Further, in the evaluation apparatus 100 and the evaluation method of the crude oil recovery effect of the present embodiment, when a rock collected from an oil reservoir layer that is the target of crude oil recovery or a rock simulating the oil reservoir layer that is the target of crude oil recovery is used as the test body 1, for example, it can be preferably used for predicting the amount of crude oil recovered when the crude oil remaining in the oil reservoir layer is recovered by the low-salt concentration water flooding method.

[0136] In the present embodiment, as an example of a preferable evaluation method, the case where the test body 1 is accommodated in the container 13 in a state satisfying all of the following conditions (a) to (c) has been described as an example. However, the test body 1 may be accommodated in the container 13 in a state satisfying, for example, the following conditions (a) and (b) and not satisfying the following condition (c), or in a state satisfying the following conditions (a) and (c) and not satisfying the following condition (b). (a) A state in which a confining pressure simulating the formation pressure of the oil reservoir layer is applied. (b) A state in which the temperature is heated to a temperature simulating the formation temperature of the oil reservoir layer. (c) A state in which an interstitial water pressure simulating the interstitial water pressure in the oil reservoir layer is applied.

[0137] <Second Embodiment> FIG. 2 is a schematic diagram for explaining an evaluation apparatus 200 for the crude oil recovery effect caused by chemical osmosis in the low-salt concentration water flooding method of the second embodiment. The evaluation device 200 of the present embodiment is different from the evaluation device 100 of the first embodiment shown in FIG. 1 in that the high-salt water storage tank 11, the high-salt water supply pipe 11a, the high-salt water discharge pipe 11b, and the pump 31 installed in the high-salt water supply pipe 11a in the effective osmotic pressure ΔP measuring device 10 of the evaluation device 100 of the first embodiment are not provided, and the water separation plate 14 is not arranged on the surface of the end cap 15 on the test body 1 side disposed on the end face of one end (the left end in FIG. 2) side of the test body 1, and the salt concentration measuring device 32 and the pressure measuring device 33 are provided. In the evaluation device 200 of the present embodiment shown in FIG. 2, the same members as those of the evaluation device 100 of the first embodiment shown in FIG. 1 are denoted by the same reference numerals, and the description thereof is omitted.

[0138] In the evaluation device 200 shown in FIG. 2, as the water pressure loading device, a device for pressurizing the inside of the low-salt water storage tank 12 that stores the low-salt concentration water 12c supplied to the test body 1 can be used. In the evaluation device 200 shown in FIG. 2, the water separation plate 14 is not arranged on the end face of one end (the left end in FIG. 2) side of the test body 1, and the high-salt concentration water 11c in the high-salt water storage tank 11 and the high-salt concentration water 11c existing on the end face of one end side of the test body 1 do not circulate. The pressure of the high-salt concentration water 11c is measured per unit time by the pressure measuring device 33 installed on the surface of the end cap 15 on the test body 1 side. Further, the salt concentration of the high-salt concentration water 11c is measured per unit time by the salt concentration measuring device 32 installed on the surface of the end cap 15 on the test body 1 side.

[0139] In the evaluation device 200 shown in FIG. 2, the high-salt concentration water 11c is not supplied to the test body 1, and only the high-salt concentration water 11c contained in the test body 1 as the high-salt concentration water 11c is used. Therefore, by using the evaluation device 200 shown in FIG. 2, the crude oil recovery effect due to chemical penetration in the low-salt concentration water flooding method for the test body 1 can be evaluated with higher accuracy under more realistic conditions as compared with the case of using the evaluation device 100 of the first embodiment shown in FIG. 1.

[0140] <Third Embodiment> FIG. 3 is a schematic diagram for explaining an evaluation apparatus 300 of the crude oil recovery effect caused by chemical osmosis in the low-salt concentration water flooding method of the third embodiment. The evaluation apparatus 300 of the present embodiment is different from the evaluation apparatus 100 of the first embodiment shown in FIG. 1 in that the test body 1 is in contact with the rock 1a containing the low-salt concentration water 12c, and the test body 1 and the low-salt concentration water 12c are in contact. In the evaluation apparatus 300 of the present embodiment shown in FIG. 3, the same members as those of the evaluation apparatus 100 of the first embodiment shown in FIG. 1 are denoted by the same reference numerals, and the description thereof is omitted.

[0141] The test body 1 shown in FIG. 3 is made of a rock containing high-salt concentration water 11c and crude oil, and has a substantially cylindrical shape, similar to the test body 1 in the first embodiment shown in FIG. 1. Unlike the first embodiment, on one end face (the right end in FIG. 3) of the test body 1, a rock 1a containing low-salt concentration water 12c having a coaxial substantially cylindrical shape with substantially the same diameter as the test body 1 is in contact. As shown in FIG. 3, the test body 1 and the rock 1a are integrated, and current electrodes 22a, 22b and a water separation plate 14 are installed on both end faces of the integrated body, respectively, and a plurality of potential electrodes 22c are installed on the side surface. The integrated test body 1 and rock 1a are sealed by a coating sheet 16 covering the entire side surface of the test body 1 and the rock 1a, and two end caps 15 disposed opposite to the outside of the water separation plate 14.

[0142] The rock 1a may be any rock containing the low-salt concentration water 12c, and may be the same rock type as the test body 1 or a different rock type from the test body 1. The rock 1a is preferably a rock having a porosity and / or pore size larger than that of the test body 1. This is because the crude oil recovery effect caused by chemical osmosis can be evaluated under more realistic conditions.

[0143] In the evaluation apparatus 300 shown in FIG. 3, the low-salt-concentration water 12c is supplied by the pump 31 to the water distribution plate 14 in contact with the end face of the rock 1a containing the low-salt-concentration water 12c from the low-salt water storage tank 12 at a substantially constant liquid feeding rate, and the low-salt-concentration water 12c in the low-salt water storage tank 12 and the low-salt-concentration water 12c contained in the rock 1a are circulated.

[0144] In the evaluation apparatus 300 shown in FIG. 3, the test piece 1 made of a rock containing high-salt-concentration water 11c and crude oil is in contact with the low-salt-concentration water 12c by contacting the rock 1a containing the low-salt-concentration water 12c. Therefore, when using the evaluation apparatus 300 shown in FIG. 3, compared with the case of using the evaluation apparatus 100 of the first embodiment shown in FIG. 1, the test piece 1 can be evaluated under conditions more consistent with the state existing in the oil reservoir layer, and the crude oil recovery effect due to chemical penetration in the low-salt-concentration water attack method on the test piece 1 can be evaluated with high precision under conditions closer to reality.

[0145] <Fourth Embodiment> FIG. 4 is a schematic diagram for explaining an evaluation apparatus 400 for the crude oil recovery effect due to chemical penetration in the low-salt-concentration water attack method of the fourth embodiment. The difference between the evaluation apparatus 400 of the present embodiment and the evaluation apparatus 300 of the third embodiment shown in FIG. 3 is that in the effective osmotic pressure ΔP measuring apparatus 10 of the evaluation apparatus 300 of the third embodiment, the high-salt water storage tank 11, the high-salt water supply pipe 11a, the high-salt water discharge pipe 11b, and the pump 31 installed in the high-salt water supply pipe 11a are not provided, and the water distribution plate 14 is not arranged on the surface of the end cap 15 on the test piece 1 side disposed on the end face on one end side (the left end side in FIG. 4) of the test piece 1, and the salt concentration measuring apparatus 32 and the pressure measuring apparatus 33 are provided. In the evaluation apparatus 400 of the present embodiment shown in FIG. 4, the same members as those of the evaluation apparatus 300 of the third embodiment shown in FIG. 3 are denoted by the same reference numerals, and the description thereof is omitted.

[0146] In the evaluation apparatus 400 shown in FIG. 4, similar to the evaluation apparatus 200 shown in FIG. 2, as the water pressure loading apparatus, an apparatus for pressurizing the inside of the low-salt water storage tank 12 that stores the low-salt-concentration water 12c supplied to the test piece 1 can be used. In the evaluation apparatus 400 shown in FIG. 4, similar to the evaluation apparatus 200 shown in FIG. 2, a water separation tray 14 is not disposed on the end face (the left end face in FIG. 2) side of one end of the test body 1, and the high-salinity concentration water 11c in the high-salinity water storage tank 11 and the high-salinity concentration water 11c existing on the end face of one end side of the test body 1 do not circulate. The pressure of the high-salinity concentration water 11c is measured every unit time by a pressure measuring device 33 installed on the surface of the end cap 15 on the test body 1 side. Further, the salinity concentration of the high-salinity concentration water 11c is measured every unit time by a salinity concentration measuring device 32 installed on the surface of the end cap 15 on the test body 1 side.

[0147] In the evaluation apparatus 400 shown in FIG. 4, similar to the evaluation apparatus 300 shown in FIG. 3, the test body 1 made of a rock containing high-salinity concentration water 11c and crude oil is in contact with the rock 1a containing low-salinity concentration water 12c, and thus is in contact with the low-salinity concentration water 12c. Moreover, in the evaluation apparatus 400 shown in FIG. 4, similar to the evaluation apparatus 200 shown in FIG. 2, the high-salinity concentration water 11c is not supplied to the test body 1, and only the high-salinity concentration water 11c contained in the test body 1 as the high-salinity concentration water 11c is used. Therefore, when the evaluation apparatus 400 shown in FIG. 4 is used, compared with the case of using the evaluation apparatuses 100, 200, and 300 of the first to third embodiments, the test body 1 can be evaluated under conditions more consistent with the state existing in the oil reservoir layer, and the crude oil recovery effect due to chemical osmosis in the low-salinity concentration water flooding method for the test body 1 can be evaluated with high precision under conditions closer to reality.

[0148] <Fifth Embodiment> FIG. 5 is a schematic diagram for explaining an evaluation apparatus 500 for the crude oil recovery effect due to chemical osmosis in the low-salinity concentration water flooding method of the fifth embodiment. The evaluation device 500 of this embodiment is different from the evaluation device 400 of the fourth embodiment shown in FIG. 4 in that the low-salt water storage tank 12, the low-salt water supply pipe 12a, the low-salt water discharge pipe 12b, and the pump 31 installed in the effective osmotic pressure ΔP measuring device 10 of the evaluation device 400 of the fourth embodiment are not provided, and the water distribution plate 14 is not installed on the surface of the end cap 15 on the side of the rock 1a that is not in contact with the test body 1 of the rock 1a containing the low-salt concentration water 12c, and the salt concentration measuring device 32 and the pressure measuring device 33 are provided. And through the pipes respectively connected to the two end caps 15, the valve 19 for supplying the low-salt concentration water 12c to the test body 1 and the valve 19 for supplying the high-salt concentration water 11c to the test body 1 are installed. In the evaluation device 500 of this embodiment shown in FIG. 5, the same members as those of the evaluation device 400 of the fourth embodiment shown in FIG. 4 are denoted by the same reference numerals, and the description thereof is omitted.

[0149] In the evaluation device 500 shown in FIG. 5, as a water pressure loading device, pipes and valves 19 respectively connected to the two end caps 15 are installed. And in the fifth embodiment, in the first step of calculating the effective osmotic pressure ΔP per unit time, the integrated test body 1 and the rock 1a are housed in the container 13, and a confinement pressure simulating the formation pressure of the oil reservoir layer is loaded on the test body 1 by a pressurizing device (not shown), and after the test body 1 is set to the temperature simulating the formation temperature of the oil reservoir layer by the heating device 18, the following operations are performed.

[0150] That is, open the valve 19 arranged on the rock 1a side, and supply the low-salt concentration water 12c to the rock 1a at a predetermined pressure by a known method through the pipe connected to the end cap 15. Also, open the valve 19 arranged on the test body 1 side, and supply the high-salt concentration water 11c to the test body 1 at a predetermined pressure by a known method through the pipe connected to the end cap 15. By performing these operations, an interstitial water pressure simulating the interstitial water pressure in the oil reservoir layer is loaded on the test body 1, and the same back pressure is applied to the high-salt concentration water 11c contained in the water separator 14 on one end side (the left end in FIG. 5), the low-salt concentration water 12c contained in the water separator 14 on the other end side (the right end in FIG. 5), and the crude oil contained in the test body 1. Then, close the two valves 19 and stop loading the interstitial water pressure from the pipe connected to the end cap 15 to the water separators 14 arranged at both ends of the test body 1, respectively.

[0151] In the evaluation apparatus 500 shown in FIG. 5, the high-salt concentration water 11c contained in the test body 1 does not circulate. Therefore, by closing the two valves 19, the back pressure in the test body 1 and the rock 1a is maintained. The pressure of the low-salt concentration water 12c is measured every unit time by the pressure measuring device 33 installed on the surface of the end cap 15 on the rock 1a side. Also, the salt concentration of the low-salt concentration water 12c is measured every unit time by the salt concentration measuring device 32 installed on the surface of the end cap 15 on the rock 1a side.

[0152] In the evaluation apparatus 500 shown in FIG. 5, the low-salt concentration water 12c is not supplied to the rock 1a, and only the low-salt concentration water 12c contained in the rock 1a is used as the low-salt concentration water 12c. For this reason, in the evaluation apparatus 500 shown in FIG. 5, the crude oil recovery effect due to chemical osmosis in the low-salt concentration water flooding method for the test body 1 can be evaluated without using the low-salt water storage tank 12, the pump 31, etc.

[0153] In addition, similar to the evaluation device 400 shown in FIG. 4, the evaluation device 500 shown in FIG. 5 has a test body 1 made of a rock containing high-salinity water 11c and crude oil in contact with a rock 1a containing low-salinity water 12c, such that the test body 1 is in contact with the low-salinity water 12c. Moreover, the high-salinity water 11c is not supplied to the test body 1, and only the high-salinity water 11c contained in the test body 1 as the high-salinity water 11c is used. Therefore, when using the evaluation device 500 shown in FIG. 5, similar to the evaluation device 400 shown in FIG. 4, the test body 1 can be evaluated under conditions consistent with the state existing in the oil reservoir layer, and the crude oil recovery effect due to chemical osmosis in the low-salinity water flooding method for the test body 1 can be evaluated with high precision under conditions closer to reality.

[0154] <Sixth Embodiment> FIG. 6 is a schematic diagram for explaining an evaluation device 600 for the crude oil recovery effect due to chemical osmosis in the low-salinity water flooding method of the sixth embodiment. The evaluation device 600 of the present embodiment differs from the evaluation device 100 of the first embodiment shown in FIG. 1 in that it does not have a container 13 for accommodating the test body 1, a pressurizing device, a heating device 18, and a water pressure loading device. Instead, the test body 1, current electrodes 22a and 22b respectively arranged at both ends of the test body 1, a water separation plate 14, an end cap 15, and a plurality of potential electrodes 22c are integrated by a resin coating layer 17 that covers the entire surface along the side surface of the test body 1. In the evaluation device 600 of the present embodiment shown in FIG. 6, the same members as those in the evaluation device 100 of the first embodiment shown in FIG. 1 are denoted by the same reference numerals, and the description thereof is omitted.

[0155] The resin coating layer 17 may be composed of a single resin layer or may be composed of two or more resin layers. When the resin coating layer 17 is composed of two resin layers, for example, it is preferably composed of an outer layer made of a substantially cylindrical acrylic resin or the like and an inner layer made of a silicon resin and / or an epoxy resin filled in the outer layer. This is because such a resin coating layer 17 can be easily manufactured by the method shown below.

[0156] First, prepare a substantially cylindrical pipe made of a resin material for the outer layer. Next, place the test body 1 around which the potential electrode 22c is wound inside the pipe. Subsequently, arrange members of the current electrodes 22a and 22b, the water separation plate 14, and the end cap 15 in this order at both ends of the test body 1, and accommodate them inside the pipe. Then, fill the space between the inner wall of the pipe and each member with a resin composition containing a resin material for the inner layer by a known method and cure it. Through the above steps, the resin coating layer 17 composed of two resin layers, an outer layer and an inner layer, can be formed.

[0157] The evaluation apparatus 600 of the present embodiment shown in FIG. 6 does not have a container 13 for accommodating the test body 1, a pressurizing device, a heating device 18, and a water pressure loading device, but has a resin coating layer 17. Therefore, compared with the evaluation apparatuses 100, 200, 300, 400, and 500 of the first to fifth embodiments, it can be easily manufactured. Further, by using the evaluation apparatus of the evaluation apparatus 600 of the present embodiment, the crude oil recovery effect due to chemical penetration in the low salt concentration water flooding method for the test body 1 can be easily evaluated.

[0158] Also, the evaluation apparatus 600 shown in FIG. 6 uses a transparent or translucent end cap 15, so that both end faces of the test body 1 can be visually observed. In this case, it is possible and preferable to evaluate the crude oil recovery effect by visually observing the exudation of oil from the end face of the test body 1. In particular, in the case of an evaluation apparatus not provided with the specific resistance measurement device 22, or when the current electrodes 22a and 22b are linear and wound along the outer surface of the test body 1 in the circumferential direction of the test body 1 near both ends of the test body 1, the end cap 15 and the test body 1 are arranged in contact with each other. For this reason, the end face of the test body 1 becomes easy to visually observe, which is preferable.

[0159] <Seventh Embodiment> In the above-described First Embodiment to Sixth Embodiment, the case where the crude oil movement amount ΔV is calculated based on the measurement result obtained by calculating the ratio of the amount of crude oil and the amount of moisture in the test body 1 every unit time has been described as an example. However, the crude oil movement amount ΔV may be calculated based on the measurement result of the amount of crude oil exuded from the test body 1 in contact with the low-salt concentration water 12c. In this case, it is preferable to calculate the crude oil movement amount ΔV based on the measurement result obtained by calculating the amount of crude oil exuded from the test body 1 in contact with the low-salt concentration water 12c every unit time. In the Seventh Embodiment, the case where the crude oil movement amount ΔV is calculated based on the measurement result of the amount of crude oil exuded from the test body 1 in contact with the low-salt concentration water 12c will be described.

[0160] [Apparatus for Evaluating Crude Oil Recovery Effect] The apparatus for evaluating the crude oil recovery effect in the Seventh Embodiment has the same effective osmotic pressure ΔP measuring device 10 as the apparatus 100 for evaluating the crude oil recovery effect in the First Embodiment shown in FIG. 1. Further, different from the First Embodiment, the apparatus for evaluating the crude oil recovery effect in the Seventh Embodiment uses the following as the crude oil movement amount ΔV measuring device and evaluation device.

[0161] (Crude Oil Movement Amount ΔV Measuring Device) In the Seventh Embodiment, as the crude oil movement amount ΔV measuring device, an oil-water separation pot (not shown) connected to the low-salt water discharge pipe 12b of the effective osmotic pressure ΔP measuring device 10 in the evaluation device 100 shown in FIG. 1, a crude oil volume measuring means (not shown) for measuring the volume of the oil (crude oil) layer separated by layers in the oil-water separation pot, and a crude oil amount calculating means (not shown) for calculating the crude oil movement amount ΔV are used. In the present embodiment, the case where the oil-water separation pot is connected to the low-salt water discharge pipe 12b will be described as an example. However, the oil-water separation pot may be connected to the low-salt water storage tank 12.

[0162] In the present embodiment, when the crude oil movement amount ΔV measuring device calculates the crude oil movement amount ΔV based on the measurement result obtained by calculating the amount of crude oil exuded from the test body 1 in contact with the low-salt concentration water 12c every unit time, a plurality of oil-water separation pots are prepared, and the oil-water separation pot connected to the low-salt water discharge pipe 12b is exchanged every unit time.

[0163] In the crude oil amount calculation means in this embodiment, when the volume of the test body 1 and the volume of the crude oil measured by the crude oil volume measurement means are input, the ratio of the volume of the recovered crude oil to the volume of the test body 1 is calculated, and the crude oil movement amount △V is input to the evaluation device. When the crude oil movement amount △V measuring device calculates the crude oil movement amount △V based on the measurement result of calculating the amount of crude oil exuded from the test body 1 per unit time, the crude oil amount calculation means calculates the ratio of the volume of the recovered crude oil to the volume of the test body 1 per unit time, and inputs it as the crude oil movement amount △V to the evaluation device.

[0164] (Evaluation device) In the seventh embodiment, similar to the first embodiment, the evaluation device 30 evaluates the crude oil recovery effect caused by chemical osmosis in the low-salt concentration water injection method for the test body 1 based on the effective osmotic pressure △P and the crude oil movement amount △V. Similar to the first embodiment, when the evaluation device 30 satisfies any one or two or more of the above-mentioned conditions (i) to (iii), it determines that there is a crude oil recovery effect caused by chemical osmosis in the low-salt concentration water injection method for the test body 1.

[0165] The evaluation device 30 in this embodiment calculates the crude oil movement amount △V based on the measurement result of calculating the amount of crude oil exuded from the test body 1 in contact with the low-salt concentration water 12c per unit time by the crude oil movement amount △V measuring device. It preferably satisfies the above conditions (ii) and / or (iii) and the crude oil movement amount △V changes per unit time. This is because it is possible to predict whether the crude oil recovery effect caused by chemical osmosis in the low-salt concentration water injection method is continuously obtained, and the crude oil recovery effect can be evaluated more accurately.

[0166] [Evaluation method of crude oil recovery effect] In the evaluation method of the crude oil recovery effect in the seventh embodiment, the first step and the third step are performed in the same manner as in the first embodiment. Also, in the seventh embodiment, different from the first embodiment, as the second step, the steps shown below are performed.

[0167] (Second step) In the first step, after bringing the test body 1 containing high-salt-concentration water 11c and crude oil into contact with low-salt-concentration water 12c, the low-salt-concentration water 12c in the low-salt-water storage tank 12, the low-salt-water supply pipe 12a, and the low-salt-water discharge pipe 12b is collected in an oil-water separation pot connected to the low-salt-water discharge pipe 12b. Next, the low-salt-concentration water 12c collected in the oil-water separation pot is separated into an oil (crude oil) layer and a water layer in the oil-water separation pot. Then, the volume of the oil (crude oil) layer separated in the oil-water separation pot is measured by crude oil volume measuring means.

[0168] After that, from the volume of the test body 1 and the volume of the crude oil measured by the crude oil volume measuring means, the ratio of the volume of the recovered crude oil to the volume of the test body 1 is calculated by the crude oil amount calculating means and input to the evaluation device as the crude oil movement amount ΔV.

[0169] When the crude oil movement amount ΔV measuring device calculates the crude oil movement amount ΔV based on the measurement result of calculating the amount of crude oil exuded from the test body 1 per unit time, in the second step, the following first operation and second operation are repeatedly performed.

[0170] (First operation) The test body 1 containing high-salt-concentration water 11c and crude oil is brought into contact with low-salt-concentration water 12c for a predetermined time, and then the low-salt-concentration water 12c in the low-salt-water storage tank 12, the low-salt-water supply pipe 12a, and the low-salt-water discharge pipe 12b is collected and recovered in an oil-water separation pot connected to the low-salt-water discharge pipe 12b. Then, the oil-water separation pot containing the low-salt-concentration water 12c is removed from the low-salt-water discharge pipe 12b.

[0171] (Second operation) Connect an oil-water separation pot that does not contain the low-salt concentration water 12c to the low-salt water discharge pipe 12b. Again, store the low-salt concentration water 12c in the low-salt water storage tank 12, and circulate the low-salt concentration water 12c in the low-salt water storage tank 12 and the low-salt concentration water 12c that contacts the end face of the test body 1. By doing this, the low-salt concentration water 12c is brought into contact with the end face on the other end (the right end in FIG. 1) side of the test body 1.

[0172] After that, the low-salt concentration water 12c contained in each oil-water separation pot is layer-separated into an oil (crude oil) layer and a water layer in each oil-water separation pot, and the volume of each oil (crude oil) layer is measured by the crude oil volume measuring means respectively. After that, based on the time when the test body 1 is in contact with the low-salt concentration water 12c, the volume of the test body 1, and the volume of the crude oil measured by the crude oil volume measuring means, the crude oil amount calculating means calculates the ratio of the volume of the recovered crude oil to the volume of the test body 1 per unit time, and inputs it into the evaluation device as the crude oil movement amount △V.

[0173] The evaluation device for the crude oil recovery effect of this embodiment includes an effective osmotic pressure △P measuring device 10 that calculates the effective osmotic pressure △P per unit time, and a device that calculates the crude oil movement amount △V generated by the salt concentration difference △C. Based on the measurement result of the amount of crude oil exuded from the test body 1 in contact with the low-salt concentration water 12c, it includes a crude oil movement amount △V measuring device that calculates the crude oil movement amount △V, and an evaluation device 30 that evaluates the presence or absence of the crude oil recovery effect. And when the evaluation device 30 satisfies any one or two or more of the above (i) to (iii) conditions, it is determined that there is a crude oil recovery effect caused by chemical osmosis in the low-salt concentration water attack method on the test body 1.

[0174] In addition, the method for evaluating the crude oil recovery effect of the present embodiment includes a first step of calculating the effective osmotic pressure ΔP for each unit time, a second step of calculating the crude oil movement amount ΔV based on the measurement result of the amount of crude oil exuded from the test body 1 in contact with the low-salt concentration water 12c, and a third step of evaluating the presence or absence of the crude oil recovery effect. And in the third step, when any one or two or more conditions selected from the above (i) to (iii) are satisfied, it is determined that there is a crude oil recovery effect caused by chemical osmosis in the low-salt concentration water attack method for the test body 1. Therefore, by using the evaluation apparatus and the evaluation method for the crude oil recovery effect of the present embodiment, it is possible to accurately evaluate whether or not a crude oil recovery effect caused by chemical osmosis in the low-salt concentration water attack method can be obtained for the test body 1 made of rock containing high-salt concentration water and crude oil.

[0175] <Eighth Embodiment> In the above-described First Embodiment to Sixth Embodiment, the case where the crude oil movement amount ΔV is calculated based on the measurement result obtained by calculating the ratio of the amount of crude oil and the amount of water in the test body 1 for each unit time has been described as an example. However, the crude oil movement amount ΔV may be calculated based on the measurement result of the mass difference of the test body 1 before the test body 1 is brought into contact with the low-salt concentration water 12c (or by bringing the test body 1 into contact with the rock 1a containing the low-salt concentration water 12c so as to be in contact with the low-salt concentration water 12c) and after the test body 1 is brought into contact with the low-salt concentration water 12c. In this case, the crude oil movement amount ΔV may be calculated based on the measurement result obtained by calculating the mass difference of the test body 1 for each unit time before the test body 1 is brought into contact with the low-salt concentration water 12c (or by bringing the test body 1 into contact with the rock 1a containing the low-salt concentration water 12c so as to be in contact with the low-salt concentration water 12c) and after the test body 1 is brought into contact with the low-salt concentration water 12c. In the Eighth Embodiment, the case where the crude oil movement amount ΔV is calculated based on the measurement result of the mass difference of the test body 1 described above will be described.

[0176] [Apparatus for Evaluating Crude Oil Recovery Effect] The evaluation device for the crude oil recovery effect in the eighth embodiment has the same effective osmotic pressure ΔP measurement device 10 as the evaluation device 100 for the crude oil recovery effect in the first embodiment shown in FIG. 1. Further, the evaluation device for the crude oil recovery effect in the eighth embodiment, unlike the first embodiment, uses the following as the crude oil movement amount ΔV measurement device and evaluation device.

[0177] (Crude oil movement amount ΔV measurement device) In the eighth embodiment, as the crude oil movement amount ΔV measurement device, a mass measurement device (not shown) that measures the mass of the test body 1 composed of a rock containing high-salt concentration water 11c and crude oil, and a crude oil amount calculation means (not shown) that calculates the crude oil movement amount ΔV are used.

[0178] In the eighth embodiment, the case where a mass measurement device that measures the mass of the test body 1 composed of a rock containing high-salt concentration water 11c and crude oil is used will be described as an example. However, when the evaluation method of the test body 1 is a method that does not use the rock 1a containing low-salt concentration water 12c, as the mass measurement device, a device that measures the mass of a test body unit including the following test body 1 may be used.

[0179] The test body unit is composed of the test body 1 and a member integrated with the test body 1. In the test body unit, the member integrated with the test body 1 may be a member made of a material whose mass does not change even when it is brought into contact with low-salt concentration water 12c together with the test body 1. For example, the current electrodes 22a, 22b and potential electrodes 22c of the specific resistance measurement device 22, the coating sheet 16 or the resin coating layer 17, the water separation plate 14, the end cap 15, etc. are mentioned.

[0180] Examples of the test body unit include those in which the test body 1 is sealed by the coating sheet 16 or the resin coating layer 17 and two end caps 15 together with the water separation plate 14 and the current electrodes 22a, 22b and potential electrodes 22c of the specific resistance measurement device 22.

[0181] The crude oil quantity calculation means calculates the mass difference of the test body 1 before and after contacting the test body 1 with the low-salt concentration water 12c, which is input with the mass of the test body 1 measured by the mass measurement device before contacting the low-salt concentration water 12c and the mass of the test body 1 after contacting the low-salt concentration water 12c, and inputs it as the crude oil movement amount △V to the evaluation device.

[0182] When the crude oil movement amount △V measuring device calculates the crude oil movement amount △V based on the measurement result of calculating the mass difference of the test body 1 before and after contacting the low-salt concentration water 12c for each unit time, the crude oil quantity calculation means calculates the mass difference of the test body 1 before and after contacting the low-salt concentration water 12c for each unit time, and inputs it as the crude oil movement amount △V to the evaluation device. In this case, it is preferable that the mass measurement device measures the mass of the test body unit described above. This is because the change in the mass of the test body 1 can be easily measured without taking out the test body 1 sealed by the coating sheet 16 or the resin coating layer 17 and the two end caps 15.

[0183] (Evaluation device) In the eighth embodiment, similar to the first embodiment, the evaluation device 30 evaluates the crude oil recovery effect caused by chemical osmosis in the low-salt concentration water attack method on the test body 1 based on the effective osmotic pressure △P and the crude oil movement amount △V. Similar to the first embodiment, when the evaluation device 30 satisfies any one or two or more of the above conditions (i) to (iii), it determines that there is a crude oil recovery effect caused by chemical osmosis in the low-salt concentration water attack method on the test body 1.

[0184] In the evaluation apparatus 30 in this embodiment, the crude oil movement amount ΔV measuring apparatus calculates the crude oil movement amount ΔV based on the measurement results of calculating the mass difference of the test body 1 per unit time before the test body 1 is brought into contact with the low salinity water 12c and after the test body 1 is brought into contact with the low salinity water 12c. It is preferable that the above conditions (ii) and / or (iii) are satisfied and the crude oil movement amount ΔV changes per unit time. This is because it is possible to predict whether the crude oil recovery effect due to chemical osmosis in the low salinity water attack method is continuously obtained, and the crude oil recovery effect can be evaluated more accurately.

[0185] [Evaluation method of crude oil recovery effect] In the evaluation method of the crude oil recovery effect in the eighth embodiment, before performing the first step, the mass of the test body 1 is measured by a mass measuring device. Then, in the same manner as in the first embodiment, the first step and the third step are performed. Also, in the eighth embodiment, different from the first embodiment, as the second step, the steps shown below are performed.

[0186] (Second step) In the first step, after the test body 1 containing the high salinity water 11c and the crude oil is brought into contact with the low salinity water 12c, the test body 1 in a sealed state by the coating sheet 16 or the resin coating layer 17 and the two end caps 15 is taken out, and the mass of the test body 1 is measured by a mass measuring device. Then, from the mass of the test body 1 measured before performing the first step and the mass of the test body 1 after being brought into contact with the low salinity water 12c, the mass difference of the test body 1 before the test body 1 is brought into contact with the low salinity water 12c and after the test body 1 is brought into contact with the low salinity water 12c is calculated by the crude oil amount calculating means, and is input into the evaluation apparatus as the crude oil movement amount ΔV.

[0187] When the crude oil movement amount ΔV measuring device calculates the crude oil movement amount ΔV based on the measurement result of calculating the mass difference of the test body 1 per unit time before the test body 1 is brought into contact with the low-salt concentration water 12c and after the test body 1 is brought into contact with the low-salt concentration water 12c, before bringing the low-salt concentration water 12c into contact with the end face of the test body 1 in the first step, the mass of the above-described test body unit is measured by a mass measuring device. Then, in the second step, the following first operation and second operation are repeatedly performed.

[0188] (First operation) After the test body 1 containing the high-salt concentration water 11c and crude oil is brought into contact with the low-salt concentration water 12c for a predetermined time, the high-salt water supply pipe 11a, the high-salt water discharge pipe 11b, the low-salt water supply pipe 12a, and the low-salt water discharge pipe 12b are removed from the end cap 15 of the above-described test body unit, and the mass of the test body unit is measured by a mass measuring device.

[0189] (Second operation) The high-salt water supply pipe 11a, the high-salt water discharge pipe 11b, the low-salt water supply pipe 12a, and the low-salt water discharge pipe 12b are attached again to the end cap 15 of the test body unit, the low-salt concentration water 12c is brought into contact with the end face of the test body 1, and the low-salt concentration water 12c in the low-salt water storage tank 12 and the low-salt concentration water 12c brought into contact with the end face of the test body 1 are circulated.

[0190] Thereafter, from the mass of the test body unit measured before bringing the low-salt concentration water 12c into contact with the end face of the test body 1 in the first step, the time when the test body 1 is brought into contact with the low-salt concentration water 12c, and the mass of the test body unit measured in the first operation, the crude oil amount calculating means calculates the mass difference of the test body 1 before and after being brought into contact with the low-salt concentration water 12c per unit time, and inputs it to the evaluation device as the crude oil movement amount ΔV.

[0191] The evaluation apparatus for crude oil recovery effect of the present embodiment includes an effective osmotic pressure ΔP measuring device 10 that calculates the effective osmotic pressure ΔP per unit time, and a device that calculates the crude oil movement amount ΔV generated by the salt concentration difference ΔC. Based on the measurement results of the mass difference of the test body 1 before the test body 1 is brought into contact with the low-salt concentration water 12c and after the test body 1 is brought into contact with the low-salt concentration water 12c, it includes a crude oil movement amount ΔV measuring device that calculates the crude oil movement amount ΔV, and an evaluation device 30 that evaluates the presence or absence of the crude oil recovery effect. And when the evaluation device 30 satisfies any one or two or more of the above conditions (i) to (iii), it is determined that there is a crude oil recovery effect caused by chemical osmosis in the low-salt concentration water attack method on the test body 1.

[0192] Further, the evaluation method for the crude oil recovery effect of the present embodiment includes a first step of calculating the effective osmotic pressure ΔP per unit time, a second step of calculating the crude oil movement amount ΔV based on the measurement results of the mass difference of the test body 1 before the test body 1 is brought into contact with the low-salt concentration water 12c and after the test body 1 is brought into contact with the low-salt concentration water 12c, and a third step of evaluating the presence or absence of the crude oil recovery effect. And when any one or two or more of the above conditions (i) to (iii) are satisfied in the third step, it is determined that there is a crude oil recovery effect caused by chemical osmosis in the low-salt concentration water attack method on the test body 1. Therefore, by using the evaluation apparatus and evaluation method for the crude oil recovery effect of the present embodiment, it is possible to accurately evaluate whether a crude oil recovery effect caused by chemical osmosis in the low-salt concentration water attack method can be obtained for the test body 1 made of rock containing high-salt concentration water and crude oil.

[0193] As described above, the embodiments of the present invention have been described in detail with reference to the drawings. However, each configuration and their combinations in each embodiment are examples, and additions, omissions, substitutions, and other changes of the configuration are possible without departing from the spirit of the present invention.

[0194] For example, in the above-described embodiment, as a preferred example of the present invention, the case where the crude oil movement amount ΔV is calculated based on any one of the measurement results selected from the following (1) to (3) was described as an example. However, the crude oil movement amount ΔV may be calculated based on any one or two or more of the measurement results selected from the following (1) to (3), and may also be calculated based on two or more of the measurement results selected from the following (1) to (3).

[0195] (1) Measurement results obtained by calculating the ratio of the amount of crude oil and the amount of water in the test body per unit time. (2) Measurement results of the amount of crude oil exuded from the test body in contact with the low-salt concentration water. (3) Measurement results of the mass difference of the test body before bringing the test body into contact with the low-salt concentration water and after bringing the test body into contact with the low-salt concentration water.

Industrial Applicability

[0196] According to the present invention, it is possible to highly accurately evaluate whether or not a crude oil recovery effect due to chemical penetration in the low-salt concentration water attack method can be obtained for a test body made of rock. Therefore, according to the present invention, by using a rock collected from an oil reservoir targeted for crude oil recovery as a test body and evaluating the crude oil recovery effect due to chemical penetration in the low-salt concentration water attack method, it is possible to highly accurately evaluate whether or not a crude oil recovery effect can be obtained when the crude oil remaining in the oil reservoir is recovered by the low-salt concentration water attack method. For this reason, the present invention contributes to an improvement in the crude oil recovery rate from the oil reservoir contained in underground rock.

Explanation of Symbols

[0197] 1…Test specimen, 10…Effective osmotic pressure △P measuring device, 11a…Pipe for supplying high-salt water, 11b…Pipe for discharging high-salt water, 11c…High-salt concentration water, 12a…Pipe for supplying low-salt water, 12b…Pipe for discharging low-salt water, 12c…Low-salt concentration water, 13…Container, 14…Water distribution tray, 15…End cap, 16…Coating sheet, 17…Resin coating layer, 18…Heating device, 19…Valve, 21…X-ray CT measuring device, 21a…X-ray irradiation device, 21b…Detector, 21c…CT value calculation device, 22…Specific resistance measuring device, 22a…Current electrode, 22b…Current electrode, 22c…Potential electrode, 22d…Specific resistance calculation device, 30, 100, 200, 300, 400, 500, 600…Evaluation device.

Claims

Claim 1 An effective osmotic pressure ΔP measuring device that consists of a rock containing high-salt-concentration water with a first salt concentration and crude oil, and is in contact with low-salt-concentration water having a second salt concentration lower than the first salt concentration, measures the pressure of the high-salt-concentration water and the pressure of the low-salt-concentration water in the test body per unit time, and calculates the effective osmotic pressure ΔP, which is the pressure difference between the high-salt-concentration water and the low-salt-concentration water, per unit time. An apparatus for calculating the amount of crude oil movement ΔV generated by the salt concentration difference ΔC between the first salt concentration and the second salt concentration, which is an apparatus for calculating the amount of crude oil movement ΔV based on any one or two or more of the following measurement results (1) to (3). An evaluation device for evaluating the presence or absence of a crude oil recovery effect, which determines that there is a crude oil recovery effect due to chemical osmosis in the low-salt-concentration water attack method on the test body when any one or two or more of the following conditions (i) to (iii) are satisfied. (1) Measurement results of calculating the ratio of the amount of crude oil to the amount of water in the test body per unit time. (2) Measurement results of the amount of crude oil exuded from the test body in contact with the low-salt-concentration water. (3) Measurement results of the mass difference of the test body before contacting the test body with the low-salt-concentration water and after contacting the test body with the low-salt-concentration water. (i) The effective osmotic pressure ΔP is greater than 0, the effective osmotic pressure ΔP changes per unit time, and the presence of the amount of crude oil movement ΔV cannot be confirmed. (ii) The effective osmotic pressure ΔP is greater than 0, the effective osmotic pressure ΔP changes per unit time, and the presence of the amount of crude oil movement ΔV can be confirmed. (iii) The effective osmotic pressure ΔP is 0, and the presence of the amount of crude oil movement ΔV can be confirmed. Claim 2 The evaluation device for the crude oil recovery effect according to claim 1, wherein the device for measuring the amount of crude oil movement ΔV includes an X-ray CT measuring device that measures the X-ray CT value of the test body per unit time and / or a specific resistance measuring device that measures the specific resistance value of the test body per unit time, and an apparatus for calculating the amount of crude oil movement ΔV that calculates the ratio of the amount of crude oil to the amount of water in the test body per unit time based on the X-ray CT value measured per unit time of the test body and / or the specific resistance value measured per unit time of the test body. Claim 3 The crude oil recovery effect evaluation device according to claim 1, wherein the crude oil movement amount ΔV measuring device calculates the crude oil movement amount ΔV based on the measurement result of (1).

4. The crude oil recovery effect evaluation device according to claim 1, wherein the test body is in contact with the low-salt concentration water-containing rock, and thus is in contact with the low-salt concentration water.

5. The test body is composed of rock collected from an oil reservoir layer for which the crude oil recovery effect is to be evaluated, or rock simulating the oil reservoir layer, has a container for accommodating the test body, a pressurizing device for applying a confinement pressure simulating the formation pressure of the oil reservoir layer to the test body accommodated in the container, a heating device for heating the test body accommodated in the container to a temperature simulating the formation temperature of the oil reservoir layer, The crude oil recovery effect evaluation device according to claim 1, comprising any one or two or more devices selected from a water pressure loading device for applying a pore water pressure simulating the pore water pressure in the oil reservoir layer to the test body accommodated in the container.

6. A first step of measuring, per unit time, the pressure of the high-salt concentration water and the pressure of the low-salt concentration water in a test body composed of rock containing high-salt concentration water and crude oil having a first salt concentration and in contact with low-salt concentration water having a second salt concentration lower than the first salt concentration, and calculating, per unit time, an effective osmotic pressure ΔP that is the pressure difference between the high-salt concentration water and the low-salt concentration water; A second step of calculating a crude oil movement amount ΔV generated by a salt concentration difference ΔC between the first salt concentration and the second salt concentration, the crude oil movement amount ΔV being calculated based on any one or two or more measurement results selected from the following (1) to (3); An evaluation method for crude oil recovery effect, comprising a third step of evaluating the presence or absence of a crude oil recovery effect, and determining that there is a crude oil recovery effect due to chemical osmosis in the low-salt concentration water flooding method for the test body when any one or two or more conditions selected from the following (i) to (iii) are satisfied. (1) A measurement result of calculating the ratio of the amount of crude oil and the amount of water in the test body per unit time. (2) A measurement result of the amount of crude oil exuded from the test body in contact with the low-salt concentration water. (3) A measurement result of the mass difference of the test body before bringing the test body into contact with the low-salt concentration water and after bringing the test body into contact with the low-salt concentration water. (i) The effective osmotic pressure ΔP is greater than 0, the effective osmotic pressure ΔP changes per unit time, and the presence of the crude oil movement amount ΔV cannot be confirmed. (ii) The effective osmotic pressure ΔP is greater than 0, the effective osmotic pressure ΔP changes per unit time, and the presence of the crude oil movement amount ΔV can be confirmed. (iii) The effective osmotic pressure ΔP is 0, and the presence of the crude oil movement amount ΔV can be confirmed.

7. In the second step, the X-ray CT value of the specimen is measured per unit time by an X-ray CT measuring device and / or the specific resistance value of the specimen is measured per unit time by a specific resistance measuring device, and based on the X-ray CT value measured per unit time of the specimen and / or the specific resistance value measured per unit time of the specimen, the ratio of the amount of crude oil and the amount of water in the specimen is calculated per unit time. The method for evaluating the crude oil recovery effect according to claim 6.

8. In the second step, based on the measurement result of (1), the crude oil movement amount ΔV is calculated. The method for evaluating the crude oil recovery effect according to claim 6.

9. The method for evaluating the crude oil recovery effect according to claim 6, wherein the specimen is in contact with the low-salt concentration water by contacting the rock containing the low-salt concentration water.

10. The specimen is composed of a rock collected from an oil reservoir layer for which the crude oil recovery effect is desired to be evaluated, or a rock simulating the oil reservoir layer, and is accommodated in a container in a state satisfying any one or two or more conditions selected from the following (a) to (c). The method for evaluating the crude oil recovery effect according to claim 6. (a) A state in which a confinement pressure simulating the formation pressure of the oil reservoir layer is applied. (b) A state in which the temperature is heated to a temperature simulating the formation temperature of the oil reservoir layer. (c) A state in which an interstitial water pressure simulating the interstitial water pressure in the oil reservoir layer is applied.

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