Evaluation device for crude oil recovery effect and evaluation method for crude oil recovery effect

Abstract

The present invention addresses the problem of providing an evaluation device and an evaluation method capable of highly accurately evaluating whether a crude oil recovery effect, which results from chemical penetration during a low-salinity water flooding method, can be obtained. An evaluation device (100) according to the present invention comprises: an effective osmotic pressure ΔP measurement device (10); a device which calculates a crude oil movement amount ΔV on the basis of a measurement result selected from among a measurement result obtained by calculating the ratio of the amount of crude oil and the amount of moisture in a test body for each unit time, a measurement result of the amount of crude oil exuded from the test body in contact with the low-salinity water, and a measurement result of the mass difference of the test body before and after the test body is brought into contact with the low-salinity water; and an evaluation device (30) which determines that the crude oil recovery effect is present when a condition is satisfied, said condition being selected from among the effective osmotic pressure ΔP being greater than 0, the effective osmotic pressure ΔP changing for each unit time, and it not being possible to confirm the presence of the crude oil movement amount ΔV, the effective osmotic pressure ΔP being greater than 0, the effective osmotic pressure ΔP changing for each unit time, and it being possible to confirm the presence of the crude oil movement amount ΔV, and the effective osmotic pressure ΔP being 0 and it being possible to confirm the presence of the crude oil movement amount ΔV.

Description

Apparatus and method for evaluating oil recovery effect

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

[0002] Crude oil in oil reservoirs contained in underground rocks can be extracted using primary recovery, which uses the pressure within the reservoir to push the crude oil up into the borehole of an oil well. However, primary recovery can only extract a portion of the crude oil present in the reservoir. For this reason, secondary recovery is used, in which water, gas, etc. are injected into the oil reservoir after the crude oil has been extracted using primary recovery to restore the pressure within the reservoir and extract the crude oil. Using secondary recovery can increase the crude oil recovery rate from the oil reservoir and increase oil production.

[0003] However, a large amount of crude oil remains in the oil reservoirs extracted using secondary recovery methods. Therefore, there is a need to recover crude oil from the oil reservoirs extracted using secondary recovery methods and further increase oil production.

[0004] Tertiary recovery, which recovers crude oil trapped in an oil reservoir after secondary recovery, is called enhanced oil recovery (EOR). Enhanced oil recovery includes a variety of 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, low-salinity water flooding has attracted attention because it has a wide range of applications and is a technology with low environmental impact. Low-salinity water flooding is a method for recovering crude oil trapped in an oil reservoir by injecting salt-containing water, which has a lower salt concentration than the brine contained in the oil reservoir, or salt-free water, into the oil reservoir.

[0006] Non-Patent Document 1 describes a proposed recovery mechanism for low-salinity waterflooding, and Non-Patent Documents 2 and 3 describe experimental evidence of enhanced crude oil recovery due to chemical osmosis in low-salinity waterflooding.

[0007] Current status of low-salinity water flooding, Satoru Takahashi, Journal of the Japan Petroleum Technology Association, Vol. 81, No. 2 (March 2016), pp. 128-135. Experimental evidence of chemical osmosis-driven improved oil recovery in low-salinity water flooding: Generation of osmotic pressure via oil-saturated sandstone, IEVG Newsletter, Vol. 10, No. 2, June 2023, pp. 4-8. Mikio Takeda, Mitsuo Manaka, Daisuke Ito, Experimental evidence of chemical osmosis-driven improved oil recovery in low-salinity water flooding: Generation of osmotic pressure via oil-saturated sandstone, Journal of Petroleum Science and Engineering 215(2022)110731

[0008] However, even if low-salinity water flooding is used to recover crude oil trapped in an oil reservoir, there are cases where the expected effect is not obtained. In such cases, before low-salinity water flooding is performed on the oil reservoir, the effectiveness of low-salinity water flooding in recovering crude oil is evaluated using test specimens taken from the oil reservoir from which the crude oil is to be recovered.

[0009] However, conventional techniques for evaluating oil recovery effectiveness have not been able to determine whether or not the crude oil trapped in the oil reservoir migrates due to chemical osmosis. In other words, it has not been possible to accurately evaluate the oil recovery effectiveness due to chemical osmosis in low-salinity water flooding using test specimens made of rock collected from the oil reservoir.

[0010] The present invention has been made in consideration of the above circumstances, and aims to provide an apparatus and method for evaluating crude oil recovery effects that can evaluate with high accuracy whether or not a crude oil recovery effect due to chemical infiltration in a low-salinity water flooding method can be achieved for a test specimen made of rock.

[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 in a test specimen made of high-salinity water of a first salinity and rock containing crude oil, the test specimen being in contact with low-salinity water having a second salinity less than the first salinity, every unit time, and calculates the effective osmotic pressure ΔP, which is the pressure difference between the high-salinity water and the low-salinity water, every unit time; a crude oil movement amount ΔV measuring device that calculates the crude oil movement amount ΔV caused by the salinity difference ΔC between the first salinity and the second salinity, and calculates the crude oil movement amount ΔV based on at least one measurement result selected from the following (1) to (3); and an evaluation device that evaluates the presence or absence of a crude oil recovery effect, and that determines that there is a crude oil recovery effect due to chemical osmosis in a low-salinity water flooding method for the test specimen if at least one condition selected from the following (i) to (iii) is satisfied.

[0012] (1) Measurement results of the ratio of the amount of crude oil to the amount of water in the test specimen calculated per unit time; (2) Measurement results of the amount of crude oil seeping out from the test specimen when it comes into contact with the low-salinity water; (3) Measurement results of the difference in mass of the test specimen before and after it comes into contact with the low-salinity water.

[0013] (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.

[0014] [2] The crude oil movement amount ΔV measurement device is an X-ray CT measurement device that measures the X-ray CT value of the test body every unit time and / or a resistivity measurement device that measures the resistivity value of the test body every unit time, and a crude oil movement amount ΔV calculation device that calculates the ratio of the amount of crude oil to the amount of water in the test body every unit time based on the X-ray CT value measured every unit time of the test body and / or the resistivity value measured every unit time of the test body.

[0015] [3] The apparatus for evaluating crude oil recovery effectiveness described in [1], wherein the crude oil movement amount ΔV measuring device calculates the crude oil movement amount ΔV based on the measurement results of (1). [4] The apparatus for evaluating crude oil recovery effectiveness described in [1], wherein the test specimen is in contact with rock containing the low-salinity water, thereby coming into contact with the low-salinity water.

[0016] [5] The apparatus for evaluating crude oil recovery effectiveness described in [1], wherein the test specimen is a rock collected from an oil reservoir for which crude oil recovery effectiveness is to be evaluated, or a rock simulating the oil reservoir, and the apparatus includes at least one of the following devices: a pressurizing device having a container for accommodating the test specimen and loading a confining pressure simulating the geopressure of the oil reservoir onto the test specimen accommodated in the container; a heating device having a container for accommodating the test specimen and heating the test specimen accommodated in the container to a temperature simulating the geotemperature of the oil reservoir; and a hydraulic loading device having a container for accommodating the test specimen and loading a pore water pressure simulating the pore water pressure in the oil reservoir onto the test specimen accommodated in the container.

[0017] [6] A method for evaluating a crude oil recovery effect, comprising: a first step of measuring the pressure of the high-salinity water and the pressure of the low-salinity water in a test specimen made of high-salinity water of a first salinity and rock containing crude oil, the test specimen being in contact with low-salinity water having a second salinity less than the first salinity, every unit time, and calculating an effective osmotic pressure ΔP, which is the pressure difference between the high-salinity water and the low-salinity water, every unit time; a second step of calculating a crude oil movement amount ΔV caused by a salinity difference ΔC between the first salinity and the second salinity, the second step calculating the crude oil movement amount ΔV based on at least one measurement result selected from the following (1) to (3); and a third step of evaluating the presence or absence of a crude oil recovery effect, the third step determining that there is a crude oil recovery effect due to chemical osmosis in a low-salinity water flooding method for the test specimen if at least one condition selected from the following (i) to (iii) is satisfied.

[0018] (1) Measurement results of the ratio of the amount of crude oil to the amount of water in the test specimen calculated per unit time; (2) Measurement results of the amount of crude oil seeping out from the test specimen when it comes into contact with the low-salinity water; (3) Measurement results of the difference in mass of the test specimen before and after it comes into contact with the low-salinity 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 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.

[0020] [7] The method for evaluating crude oil recovery effectiveness described in [6], wherein in the second step, the X-ray CT value of the test specimen is measured every unit time using an X-ray CT measurement device and / or the resistivity value of the test specimen is measured every unit time using a resistivity measurement device, and the ratio of the amount of crude oil to the amount of water in the test specimen is calculated every unit time based on the X-ray CT value measured every unit time of the test specimen and / or the resistivity value measured every unit time of the test specimen.

[0021] [8] The method for evaluating crude oil recovery effectiveness according to [6], wherein in the second step, the amount of crude oil movement ΔV is calculated based on the measurement results of (1). [9] The method for evaluating crude oil recovery effectiveness according to [6], wherein the test specimen is in contact with rock containing the low-salinity water, thereby coming into contact with the low-salinity water.

[0022]

[10] The method for evaluating crude oil recovery effectiveness according to [6], wherein the test specimen is made of a rock collected from an oil reservoir for which crude oil recovery effectiveness is to be evaluated, or a rock simulating the oil reservoir, and is contained in a container in a state that satisfies at least one condition selected from the following (a) to (c): (a) a state in which a confining pressure simulating the geopressure of the oil reservoir is applied; (b) a state in which the test specimen is heated to a temperature simulating the geotemperature of the oil reservoir; (c) a state in which a pore water pressure simulating the pore water pressure in the oil reservoir is applied.

[0023] By using the crude oil recovery effect evaluation device and crude oil recovery effect evaluation method of the present invention, it is possible to evaluate with high accuracy whether a crude oil recovery effect due to chemical infiltration in a low-salinity water flooding method can be achieved for a test specimen made of rock. Therefore, according to the present invention, for example, by using rock collected from an oil reservoir that is the target of crude oil recovery as a test specimen, it is possible to evaluate with high accuracy whether a crude oil recovery effect can be achieved when crude oil remaining in the oil reservoir is recovered by a low-salinity water flooding method.

[0024] FIG. 1 is a schematic diagram for explaining an evaluation device for the crude oil recovery effect due to chemical osmosis in a low-salinity water flood according to a first embodiment. FIG. 2 is a schematic diagram for explaining an evaluation device for the crude oil recovery effect due to chemical osmosis in a low-salinity water flood according to a second embodiment. FIG. 3 is a schematic diagram for explaining an evaluation device for the crude oil recovery effect due to chemical osmosis in a low-salinity water flood according to a third embodiment. FIG. 4 is a schematic diagram for explaining an evaluation device for the crude oil recovery effect due to chemical osmosis in a low-salinity water flood according to a fourth embodiment. FIG. 5 is a schematic diagram for explaining an evaluation device for the crude oil recovery effect due to chemical osmosis in a low-salinity water flood according to a fifth embodiment. FIG. 6 is a schematic diagram for explaining an evaluation device for the crude oil recovery effect due to chemical osmosis in a low-salinity water flood according to a sixth embodiment.

[0025] In order to solve the above problems and to be able to evaluate with high accuracy the crude oil recovery effect due to chemical infiltration in low-salinity water flooding using test specimens made of rocks collected from oil reservoirs that are the target of crude oil recovery, the inventors have focused on the enhanced recovery mechanism of low-salinity water flooding and conducted extensive research as described below.

[0026] When a test specimen consisting of high-salinity water and rock containing 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. When this pressure difference occurs, chemical osmosis occurs, driven by the chemical potential, and water moves from the low-salinity water to the high-salinity water. Chemical osmosis occurs through semipermeable membranes such as clay minerals contained in the rock that forms the test specimen, a water film existing at the boundary between the crude oil and the clay minerals, and the crude oil itself.

[0027] Even inside the test specimen, a rock containing high-salinity water and crude oil, water infiltrates from the low-salinity water through the semipermeable membrane by chemical osmosis, generating an effective osmotic pressure ΔP in the high-salinity water. The effective osmotic pressure ΔP generated in the high-salinity water also generates a pressure flow of the crude oil and pore water mixture from the high-salinity water to the low-salinity water. As a result, a volume of the crude oil and pore water mixture equal to the volume of the water that infiltrated the rock by chemical osmosis seeps out from the edge of the rock in contact with the low-salinity water.

[0028] Based on these findings, the inventors concluded that if a test specimen made of rock has an effective osmotic pressure ΔP greater than 0, the test specimen can be evaluated as a test specimen that can achieve crude oil recovery by chemical osmosis in a low-salinity water flood. Specifically, when a test specimen made of high-salinity water and rock containing crude oil is placed in contact with low-salinity water, and the effective osmotic pressure ΔP generated by the chemical potential difference between the high-salinity water and the low-salinity water exceeds 0, a pressure flow of a mixture of crude oil and pore water from the high-salinity water to the low-salinity water occurs in the test specimen, driven by the effective osmotic pressure ΔP. If a test specimen can be evaluated as a test specimen that can achieve crude oil recovery by chemical osmosis in a low-salinity water flood, it can be expected that crude oil will seep from the rock forming the test specimen into the low-salinity water.

[0029] However, the inventors' investigation into the effectiveness of chemical osmosis in crude oil recovery during low-salinity water flooding revealed that even in rock specimens with an effective osmotic pressure ΔP greater than zero, the oil recovery effect may not be sustained. More specifically, the seepage of a mixture of crude oil and pore water from the rock into low-salinity water due to chemical osmosis does not occur uniformly from within the rock. Pores of various sizes are connected within the rock, and each pore has its own viscous resistance and threshold pressure Pth (capillary pressure) depending on its size, which affect the degree of seepage of the mixture. The smaller the pore size, the higher the threshold pressure Pth. Therefore, the mixture of crude oil and pore water present within the rock preferentially moves through pores with low viscous resistance and threshold pressure Pth, i.e., a pore network formed by connecting large pores, and is transported to the outside of the test specimen.

[0030] Furthermore, even in a pore network through which a crude oil and pore water mixture preferentially migrates, the network is composed of pores of various sizes, and therefore the viscous resistance and threshold pressure Pth are not uniform. A large driving force (large effective osmotic pressure ΔP) is required for a moving crude oil and pore water mixture (more precisely, the interface between the crude oil and pore water) to pass through pores with a large threshold pressure Pth (small pores). Therefore, when a crude oil and pore water mixture attempts to pass through a small pore, if the mixture does not have an effective osmotic pressure ΔP that matches the threshold pressure Pth of the pore, the movement of the crude oil and pore water mixture will temporarily stop. Meanwhile, in semipermeable membranes in rock, even while the movement of the crude oil and pore water mixture is stopped, chemical osmosis occurs from low-salinity water to high-salinity water, increasing the effective osmotic pressure ΔP. When the effective osmotic pressure ΔP exceeds the threshold pressure Pth of the small pores that were preventing the movement of the mixture of crude oil and pore water, the mixture of crude oil and pore water passes through the small pores. In other words, the mixture of crude oil and pore water begins to move again, and the once-increased effective osmotic pressure ΔP decreases back to its original value in line with the viscous resistance of the pores.

[0031] Thus, while crude oil is seeping out of the rock by chemical osmosis through the semipermeable membrane, the effective osmotic pressure ΔP repeatedly increases and decreases depending on the viscous resistance of the pores through which the mixture of crude oil and pore water is trying to pass and the threshold pressure Pth. However, crude oil present in pores (small pores) with a large threshold pressure Pth that exceeds the driving force of the repeatedly increasing and decreasing effective osmotic pressure ΔP does not move even when chemical osmosis occurs in those pores from low-salinity water to high-salinity water, and remains inside the rock.

[0032] For these reasons, even after the oil recovery effect from the test specimen due to chemical osmosis has disappeared, crude oil may remain inside the rock that makes up the test specimen. In this case, chemical osmosis continues to occur inside the test specimen through semipermeable membranes such as clay minerals contained in the rock, a water film existing at the boundary between the clay minerals and the crude oil, and the remaining crude oil itself, so the effective osmotic pressure ΔP exceeds 0. However, no oil recovery effect is obtained.

[0033] When chemical osmosis without oil recovery continues, no crude oil is extracted from the rocks that make up the specimen. Therefore, the amount of crude oil in the specimen remains constant over time. Furthermore, the effective osmotic pressure ΔP generated by chemical osmosis remains constant over time, remaining substantially constant at a value greater than zero.

[0034] On the other hand, if the effective osmotic pressure ΔP is greater than 0 and repeatedly increases and decreases over time (in other words, changes over time), it can be assumed that crude oil is seeping from the rock forming the test specimen into the low-salinity water. As a result, the rock containing the test specimen can be evaluated as being capable of achieving crude oil recovery by chemical osmosis in a low-salinity water flood.

[0035] The inventors also focused on the size of pores in rock specimens and conducted extensive research into the effectiveness of chemical osmosis in recovering crude oil from low-salinity water flooding. As a result, they found that when the specimen is a rock with relatively large pores (for example, pores with a minimum distance of 1 μm or more between opposing walls), the effective osmotic pressure ΔP may be zero even though chemical osmosis is occurring inside the specimen due to the salinity difference ΔC.

[0036] This is because the effective osmotic pressure ΔP is generated according to the viscous resistance and the threshold pressure Pth, which depend on the size of the pores. The larger the pores, the smaller the effective osmotic pressure ΔP at which the crude oil and water mixture undergoes pressure flow. More specifically, although a local internal effective osmotic pressure is generated inside the test specimen according to the size of the pores, the crude oil and water mixture immediately moves due to the small viscous resistance, and the local internal effective osmotic pressure dissipates. As a result, it is estimated that the effective osmotic pressure ΔP, which is the pressure difference between the high-salinity water present near the outer surface of the test specimen or the high-salinity water removed from the test specimen and the low-salinity water present near the outer surface of the test specimen or the low-salinity water removed from the test specimen, may also be below the detection limit of the pressure measurement device.

[0037] Therefore, the inventors conducted extensive research to evaluate whether or not a crude oil recovery effect due to chemical osmosis in low-salinity water flooding can be achieved even when a test specimen consisting of high-salinity water and rock containing crude oil is in contact with low-salinity water and the effective osmotic pressure ΔP is 0. As a result, they found that even when the effective osmotic pressure ΔP is 0, it is possible to detect whether or not chemical osmosis is occurring based on the amount of crude oil movement ΔV shown below, and thus completed the present invention.

[0038] The crude oil migration amount ΔV is the amount of crude oil migration ΔV caused by chemical osmosis caused by the salinity difference ΔC. The crude oil migration amount ΔV is calculated based on at least one measurement result selected from the following (1) to (3): (1) a measurement result in which the ratio of the amount of crude oil to the amount of water in the test specimen is calculated per unit time; (2) a measurement result of the amount of crude oil that seeped out from the test specimen in contact with the low-salinity water; and (3) a measurement result of the mass difference of the test specimen before and after contacting the test specimen with the low-salinity water.

[0039] If the amount of crude oil movement ΔV can be calculated based on the results of at least one of the measurements (1) to (3) above, it can be evaluated that there is an oil recovery effect due to chemical osmosis in low-salinity water flooding, even if the effective osmotic pressure ΔP is 0. Furthermore, the larger the calculated amount of crude oil movement ΔV, the higher the oil recovery effect due to chemical osmosis in low-salinity water flooding can be evaluated.

[0040] However, when the test specimen is a rock having relatively small pores (for example, pores in which the shortest distance between opposing wall surfaces is less than 1 μm), the crude oil migration amount ΔV is small, so that the crude oil migration amount ΔV cannot be measured or the measurement error of the crude oil migration amount ΔV becomes large. Therefore, it is difficult to evaluate with sufficient accuracy whether or not a crude oil recovery effect can be achieved by a low-salinity water flooding method using the crude oil migration amount ΔV. Therefore, when the test specimen is a rock having relatively small pores, if the effective osmotic pressure ΔP is 0, the crude oil recovery effect due to chemical osmosis in a low-salinity water flooding method cannot be achieved.

[0041] Based on these findings, the inventors conducted extensive research to develop a method that can accurately evaluate whether or not a crude oil recovery effect due to chemical infiltration can be achieved in low-salinity water flooding, regardless of whether the test rock has large or small pores.

[0042] As a result, for a test specimen consisting of high-salinity water and rock containing crude oil collected from an oil reservoir that is the target of crude oil recovery, the effective osmotic pressure ΔP was calculated per unit time while the test specimen was in contact with low-salinity water, and based on the crude oil movement amount ΔV, it was found that if at least one of the following conditions (i) to (iii) is satisfied, it can be determined that there is a crude oil recovery effect due to chemical osmosis in low-salinity water flooding for the test specimen, and the present invention was completed.

[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] The crude oil recovery effect evaluation device and crude oil recovery effect evaluation method of the present invention will be described in detail below with reference to the drawings. Note that the drawings used in the following description may conveniently show characteristic portions enlarged to make the features of the present invention easier to understand. Therefore, the dimensional ratios of each component may differ from the actual ones. The scope of the present invention is not limited to the embodiment described here, and various modifications may be made without departing from the spirit of the present invention. Furthermore, when multiple upper and lower limit values ​​are specified for a specific parameter, any of these upper and lower limit values ​​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 illustrating an apparatus for evaluating the effect of crude oil recovery due to chemical osmosis in a low-salinity water flood according to a first embodiment. The evaluation apparatus 100 of this embodiment uses a test specimen 1 consisting of high-salinity water 11c and rock containing crude oil as the evaluation target. The test specimen 1 is a rock for which the effect of crude oil recovery due to chemical osmosis in a low-salinity water flood is to be evaluated, and is preferably a rock collected from an oil reservoir from which crude oil recovery is to be performed. The test specimen 1 may also be a rock simulating the oil reservoir from which crude oil recovery is to be performed.

[0046] As shown in Fig. 1, the test specimen 1 preferably contains high-salinity water 11c, which is the pore water of an oil reservoir. When the test specimen 1 is a rock simulating an oil reservoir from which crude oil is to be recovered, the test specimen 1 may contain saline water prepared using sodium chloride or the like, instead of the high-salinity water 11c, which is the pore water of an oil reservoir, and which has a saline content equivalent to that of the pore water of an oil reservoir.

[0047] Furthermore, the crude oil contained in the test specimen 1 as the target of crude oil recovery is preferably the crude oil contained in the rock from which the crude oil recovery effect is to be evaluated, but it may also be an oil simulating crude oil impregnated into the test specimen 1. Examples of oil simulating crude oil include liquid paraffin and toluene. The type of rock that is the test specimen 1 is not particularly limited, and examples include mudstone, sandstone, carbonate rock, etc.

[0048] The specimen 1 shown in FIG. 1 has a substantially cylindrical shape. In this embodiment, the specimen 1 is sealed by a cover sheet 16 that covers the entire side surface of the specimen 1 and end caps 15 that are respectively disposed on both end surfaces of the specimen 1. The cover sheet 16 is made of a flexible sheet that is water-resistant, chemical-resistant, and oil-resistant, such as a rubber sheet made of fluororubber. The end caps 15 may be made of a resin such as polyether ether ketone (PEEK). The end caps 15 are substantially circular in plan view. The surface of the end cap 15 facing the specimen 1 may be provided with multiple grooves that diffuse the high-salinity water 11c or low-salinity water 12c in the diameter direction of the specimen 1.

[0049] As shown in FIG. 1 , a water distribution basin 14, which is generally circular in plan view, is disposed between the end cap 15 and the test specimen 1. The water distribution basin 14 stores high-salinity water 11c or low-salinity water 12c, and contacts the end face of the test specimen 1 facing the water distribution basin 14 with the high-salinity water 11c or low-salinity water 12c uniformly in the diameter direction of the test specimen 1 without applying pressure. In this embodiment, the installation of the water distribution basin 14 allows the high-salinity water 11c or low-salinity water 12c to be uniformly dispersed from the end face of the test specimen 1, preventing it from being forcibly injected from the end face of the test specimen 1. The water distribution basin 14 can be, for example, a porous resin plate made of a resin such as polyether ether ketone (PEEK).

[0050] In this embodiment, an end cap 15 that functions as a water distribution plate may be used instead of the water distribution plate 14. An example of such an end cap 15 is one that has a plurality of grooves on the surface on the test specimen 1 side for diffusing the high-salinity water 11c or the low-salinity water 12c in the diameter direction of the test specimen 1 and bringing the high-salinity water 11c or the low-salinity water 12c into contact with the test specimen 1.

[0051] 1, current electrodes 22a and 22b of a resistivity measuring device 22 are disposed between both ends of the test piece 1 and the water distribution board 14, in contact with the end faces of the test piece 1. As the current electrodes 22a and 22b, for example, metal meshes having a substantially circular shape in a plan view can be used.

[0052] As shown in FIG. 1 , the crude oil recovery effect evaluation device 100 of this embodiment includes a container 13 for accommodating the test specimen 1, an effective osmotic pressure ΔP measuring device 10 having a pressure measuring device 33 for measuring the pressure of the high-salinity water 11c and the low-salinity water 12c, and a salinity measuring device 32 for measuring the salinity of the high-salinity water 11c and the low-salinity water 12c, a crude oil movement amount ΔV measuring device (not shown) having an X-ray CT measuring device 21, a resistivity measuring device 22, and a crude oil movement amount ΔV calculation device (not shown), and an evaluation device 30.

[0053] 1 is preferably made of a material that can transmit X-rays irradiated from the X-ray irradiation device 21a to the test specimen 1, and that can provide sufficient pressure resistance when a confining pressure is applied to the test specimen 1 and sufficient heat resistance when the test specimen 1 is heated to a temperature that simulates the geothermal temperature of an oil reservoir. Specifically, the test specimen 13 is preferably made of a resin such as polyether ether ketone (PEEK) and has a sufficient thickness.

[0054] The shape of the container 13 can be, for example, cylindrical as shown in Figure 1, and is not particularly limited as long as it can accommodate the test specimen 1 on which the current electrodes 22a, 22b and the potential electrode 22c are installed, and the water distribution plates 14 placed at both ends of the test specimen 1, sealed by the covering sheet 16 and the two end caps 15.

[0055] The evaluation device 100 for evaluating the effect of crude oil recovery of this embodiment preferably includes a pressurizing device (not shown) that applies a confining pressure simulating the geological pressure of an oil reservoir to the test specimen 1 contained in the container 13, a heating device 18 that heats the test specimen 1 contained in the container 13 to a temperature simulating the geological temperature of the oil reservoir, and a hydraulic loading device (not shown) that applies a pore water pressure simulating the pore water pressure in the oil reservoir to the test specimen 1 contained in the container 13. This is because, by subjecting the test specimen 1 to a confining pressure, temperature, and pore water pressure simulating those of the oil reservoir that is the target of crude oil recovery, the test specimen 1 can be evaluated under conditions that more closely match the conditions present in the oil reservoir. As a result, by using the evaluation device 100 for this embodiment, the effect of crude oil recovery due to chemical infiltration in a low-salinity water flooding of the test specimen 1 can be evaluated with high accuracy under more realistic conditions.

[0056] When the confining pressure applied to the test specimen 1 contained in the container 13 is increased, the pores of the clay mineral become smaller and the semipermeability increases, which tends to increase the amount of chemical osmosis and the effective osmotic pressure ΔP. In this embodiment, it is preferable to use a pressurizing device to apply a confining pressure simulating the geopressure of an oil reservoir to the test specimen 1 contained in the container 13, thereby increasing the confining pressure applied to the test specimen 1 to a level equivalent to the geopressure of the oil reservoir. Any pressurizing device can be used as long as it can apply a sufficient confining pressure simulating the geopressure of an oil reservoir to the test specimen 1 contained in the container 13, and any known device capable of pressurizing the inside of the container 13 can be used.

[0057] Increasing the temperature of the test specimen 1 contained in the container 13 reduces the viscosity of the crude oil and reduces the viscous resistance of the pores through which the mixture of crude oil and pore water tries to pass. This makes it easier for the crude oil to seep out of small pores, and tends to facilitate the movement of the mixture of crude oil and water inside the test specimen 1. In this embodiment, it is preferable to heat the test specimen 1 contained in the container 13 using the heating device 18, so that the test specimen 1 has a temperature that simulates the ground temperature of the oil reservoir.

[0058] The heating device 18 may be any device that can heat the test specimen 1 housed in the container 13 to a temperature that simulates the ground temperature of the oil reservoir, and may be, for example, a known heater such as a sheet heater arranged to cover the outer periphery of the cylindrical container 13 as shown in Fig. 1. As the sheet heater, for example, a carbon heat heater or a resin sheet heater may be used.

[0059] 1, the heating device 18 may be disposed along the outer surface of the container 13, or may be installed inside the container 13. The heating device 18 is preferably disposed so as to be able to transmit X-rays irradiated onto the specimen 1 from an X-ray irradiation device 21a (described later) and / or is preferably made of a material that is able to transmit X-rays.

[0060] Increasing the pore water pressure of the test specimen 1 contained in the container 13 intensifies molecular diffusion (the true nature of chemical osmosis), which tends to increase the amount of chemical osmosis. Furthermore, strictly speaking, crude oil and pore water are compressible fluids, and under high pore water pressure, the effective seepage pressure ΔP for the same amount of chemical osmosis tends to be larger than under low pore water pressure. In this embodiment, it is preferable to use a hydraulic loading device to load a pore water pressure simulating the pore water pressure in an oil reservoir onto the test specimen 1 contained in the container 13, thereby increasing the pore water pressure of the test specimen 1 to approximately the same as the pore water pressure of the oil reservoir.

[0061] The hydraulic loading device may be any device that can apply pore water pressure simulating the pore water pressure in an oil reservoir to the test specimen 1 contained in the container 13. As the hydraulic loading device, for example, a device that can apply pore water pressure to the test specimen 1 by supplying low-salinity water 12c and / or high-salinity water 11c to the test specimen 1 at a predetermined pressure can be used, and known devices can be used, such as a device that pressurizes the low-salinity water storage tank 12 that stores the low-salinity water 12c to be supplied to the test specimen 1, or a device that pressurizes the high-salinity water storage tank 11 that stores the high-salinity water 11c.

[0062] In this embodiment, an example will be described in which a pressurizing device, a heating device, and a hydraulic loading device are provided, but the heating device and hydraulic loading device do not necessarily have to 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 this embodiment has a high-salinity water storage tank 11 for storing high-salinity water 11c, a high-salinity water supply pipe 11a, a high-salinity water discharge pipe 11b, a low-salinity water storage tank 12 for storing low-salinity water 12c, a low-salinity water supply pipe 12a, a low-salinity water discharge pipe 12b, a pressure measuring device 33, a salinity measuring device 32, and an effective osmotic pressure ΔP calculating device (not shown).

[0064] A high-salinity water storage tank 11 containing high-salinity water 11c is arranged at one longitudinal end of the test specimen 1 (the left end in FIG. 1), and a low-salinity water storage tank 12 containing low-salinity water 12c is arranged at the other longitudinal end (the right end in FIG. 1).

[0065] The high-salinity water storage tank 11 is connected to a high-salinity water supply pipe 11a that passes through the end cap 15 and supplies high-salinity water 11c to a water distribution plate 14 that contacts the end face of the test specimen 1, and a high-salinity water discharge pipe 11b that passes through the end cap 15 and discharges high-salinity water 11c from the water distribution plate 14 that contacts the end face of the test specimen 1.

[0066] 1 , the high-salinity water supply pipe 11a is provided with a pump 31 that supplies high-salinity water 11c to a water distribution basin 14 that is in contact with the end face of the test specimen 1. In this embodiment, the pump 31 supplies the high-salinity water 11c to the water distribution basin 14 that is in contact with the end face of the test specimen 1 at a substantially constant liquid feed rate, and the high-salinity water 11c in the high-salinity water storage tank 11 and the high-salinity water 11c contained in the water distribution basin 14 that is in contact with the end face of the test specimen 1 are circulated. The flow rate at which the high-salinity water 11c is supplied by the pump 31 is set to a flow rate that does not forcefully inject the high-salinity water 11c into the end face of the test specimen 1, and can be, for example, about 10 mL / min.

[0067] The low-salinity water storage tank 12 is connected to a low-salinity water supply pipe 12a that passes through the end cap 15 and supplies low-salinity water 12c to a water distribution plate 14 that contacts the end face of the test specimen 1, and a low-salinity water discharge pipe 12b that passes through the end cap 15 and discharges the low-salinity water 12c from the water distribution plate 14 that contacts the end face of the test specimen 1.

[0068] 1 , the low-salinity water supply pipe 12a is provided with a pump 31 that supplies low-salinity water 12c to a water distribution basin 14 that is in contact with the end face of the test specimen 1. In this embodiment, the pump 31 supplies the low-salinity water 12c to the water distribution basin 14 that is in contact with the end face of the test specimen 1 at a substantially constant liquid flow rate, and the low-salinity water 12c in the low-salinity water storage tank 12 and the low-salinity water 12c that is in contact with the water distribution basin 14 that is in contact with the end face of the test specimen 1 are circulated. The flow rate at which the low-salinity water 12c is supplied by the pump 31 is set to a flow rate that does not forcefully inject the low-salinity water 12c into the end face of the test specimen 1, and can be, for example, about 10 mL / min.

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

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

[0071] The low-salinity water 12c has a second salinity less than the first salinity. The salinity (second salinity) of the low-salinity water 12c may be less than the first salinity, and is preferably the same as that of low-salinity water that can be used or refined near the oil reservoir from which the test specimen 1 was extracted. This is because, when crude oil remaining in the oil reservoir from which the test specimen 1 was extracted is recovered by low-salinity water flooding using low-salinity water that can be used or refined near the oil reservoir, evaluation can be performed under more suitable conditions, and the crude oil recovery effect due to chemical osmosis in low-salinity water flooding on the test specimen 1 can be evaluated under more realistic conditions. The low-salinity water 12c may be water that does not contain salt.

[0072] Further, the high-salinity water discharge pipe 11b is provided with a pressure measuring device 33 that measures the pressure of the high-salinity water 11c flowing through the high-salinity water discharge pipe 11b per unit time, and a salinity measuring device 32 that measures the salinity of the high-salinity water 11c flowing through the high-salinity water discharge pipe 11b per unit time. Further, the low-salinity water discharge pipe 12b is provided with a pressure measuring device 33 that measures the pressure of the low-salinity water 12c flowing through the low-salinity water discharge pipe 12b per unit time, and a salinity measuring device 32 that measures the salinity of the low-salinity water 12c flowing through the low-salinity water discharge pipe 12b per unit time.

[0073] The effective osmotic pressure ΔP is generated by placing a test specimen 1 made of high-salinity water 11c and rock containing crude oil in contact with low-salinity water 12c, and gradually increases from the first point in time to the second point in time when the test specimen 1 containing high-salinity water 11c is brought into contact with the low-salinity water 12c, and then repeatedly increases and decreases from the second point in time to the third point in time, and becomes approximately constant from the third point onwards.

[0074] In this embodiment, the frequency of measuring the pressure and salinity of the high-salinity water 11c and the low-salinity water 12c per unit time may be constant or may be varied as necessary. The frequency of measuring the pressure and salinity of the high-salinity water 11c and the low-salinity water 12c per unit time is preferably, for example, every 2 seconds to every 10 minutes from the first time point to the second time point, when the effective osmotic pressure ΔP gradually increases. Furthermore, the frequency of measuring the pressure and salinity of the high-salinity water 11c and the low-salinity water 12c per unit time is preferably, for example, every 30 minutes to every hour from the second time point to the third time point, when the effective osmotic pressure ΔP repeatedly increases and decreases.

[0075] It is preferable to terminate the measurement of the pressure and salinity of the high-salinity water 11c and the low-salinity water 12c after confirming that the effective osmotic pressure ΔP, which has repeatedly increased and decreased since the second time point, has become substantially constant (at the third time point). In other words, it is preferable to continue measuring the pressure and salinity of the high-salinity water 11c and the low-salinity water 12c every 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 resulting from chemical osmosis in the low-salinity water flooding is being continuously obtained.

[0076] In the high-salinity water 11c, the frequency of measuring the pressure and the frequency of measuring the salinity may be the same or different. In the low-salinity water 12c, the frequency of measuring the pressure and the frequency of measuring the salinity may be the same or different. The frequencies of measuring the pressure in the high-salinity water 11c and the low-salinity water 12c may be the same or different, but are preferably the same. This is because whether or not a crude oil recovery effect due to chemical osmosis in a low-salinity water flooding method is being achieved can be predicted with high accuracy by the increase or decrease in the effective osmotic pressure ΔP.

[0077] The pressure measuring device 33 that measures the pressure of the high-salinity water 11c and the low-salinity water 12c can be a known pressure measuring device such as a pressure sensor or a differential pressure sensor. The pressure measuring device 33 that measures the pressure of the high-salinity water 11c and the pressure measuring device 33 that measures the pressure of the low-salinity water 12c may be the same or different. In this embodiment, the pressures of the high-salinity water 11c and the low-salinity water 12c measured by the pressure measuring 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-salinity water 11c and the low-salinity water 12c, per unit time by inputting the pressure signals of the high-salinity water 11c and the low-salinity water 12c measured by the pressure measurement device 33. As a result, the effective osmotic pressure ΔP measurement device 10 of this embodiment is configured to calculate the effective osmotic pressure ΔP of the test specimen 1, which is made of the high-salinity water 11c and rock containing crude oil and is in contact with the low-salinity water 12c, 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] Furthermore, a known salinity measurement device such as an electrical conductivity electrode can be used as the salinity measurement device 32 for the high-salinity water 11c and the low-salinity water 12c. In this embodiment, the salinities of the high-salinity water 11c and the low-salinity water 12c measured by the salinity measurement device are input to a salinity difference ΔC calculation device (not shown).

[0080] The salinity difference ΔC calculation device calculates the salinity difference ΔC between the high-salinity water 11c and the low-salinity water 12c per unit time by inputting the signals of the salinities of the high-salinity water 11c and the low-salinity water 12c measured by the salinity measurement device 32. As a result, the effective osmotic pressure ΔP measurement device 10 of this embodiment is configured to calculate the salinity difference ΔC per unit time. The salinity difference ΔC calculated by the salinity difference ΔC calculation device is input to the evaluation device 30.

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

[0082] (Crude oil movement amount ΔV measuring device) The crude oil movement amount ΔV measuring device in the crude oil recovery effect evaluation device 100 of this embodiment is a device that calculates the crude oil movement amount ΔV caused by chemical osmosis that occurs due to the salinity difference ΔC between the salinity of the high salinity water 11c (first salinity) and the salinity of the low salinity water 12c (second salinity).

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

[0084] The X-ray CT measurement device 21 measures the X-ray CT value of the test piece 1 every unit time. As shown in FIG. 1, the X-ray CT measurement device 21 includes an X-ray irradiator 21a, a detector 21b, and a CT value calculation device 21c. For example, as shown in FIG. 1, the X-ray irradiator 21a rotates circumferentially around the test piece 1 along the side surface of the cylindrical test piece 1 contained in the container 13 and moves along the longitudinal direction of the test piece 1, irradiating the test piece 1 with X-rays. The detector 21b is disposed opposite the X-ray irradiator 21a across the test piece 1, and detects the amount of X-rays transmitted through the test piece 1 while rotating circumferentially around the test piece 1 along the side surface of the cylindrical test piece 1 and moving along the longitudinal direction of the test piece 1 together with the X-ray irradiator 21a. The CT value calculation device 21c calculates an X-ray CT value corresponding to the density of the test piece 1 from the detection result detected by the detector 21b.

[0085] In the present embodiment, an example has been described in which the X-ray irradiator 21a and the detector 21b rotate circumferentially around the test specimen 1 along the side surface of the test specimen 1 housed in the container 13 and move along the length of the test specimen 1. However, the direction in which the X-ray irradiator 21a and the detector 21b are moved is not particularly limited as long as they can measure the X-ray CT value of the entire test specimen 1. For example, the X-ray irradiator 21a may irradiate the test specimen 1 with X-rays while rotating along the length of the cylindrical test specimen 1 housed in the container 13 and moving along the diameter of the test specimen 1. In this case, the detector 21b is disposed opposite the X-ray irradiator 21a with the test specimen 1 interposed therebetween, and detects the amount of X-rays that have passed through the test specimen 1 while rotating along the length of the cylindrical test specimen 1 and moving along the diameter of the test specimen 1 together with the X-ray irradiator 21a.

[0086] In this embodiment, the X-ray CT value is measured by the X-ray CT measurement device 21 every unit time and input to the crude oil movement amount ΔV calculation device described below. The frequency of measuring the X-ray CT value of the test specimen 1 can be, for example, every 5 minutes to every hour, and may be constant or may be changed as necessary. It is preferable that the measurement of the X-ray CT value of the test specimen 1 starts when the test specimen 1 is brought into contact with the low-salinity water 12c and ends after it is confirmed that no change in the X-ray CT value is observed. In other words, it is preferable that the measurement of the X-ray CT value of the test specimen 1 is 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 such as one used for medical purposes can be used. As the X-ray CT measurement device 21, a microfocus X-ray CT measurement device or the like may also be used. When a microfocus X-ray CT measurement device is used, the movement of crude oil can be evaluated using not only the X-ray CT value of the test piece 1 but also high-resolution images.

[0088] Furthermore, the X-ray CT measurement device 21 may be, for example, an X-ray CT measurement device having a base with a table on which the test piece 1 contained in the container 13 is rotatably placed, and an X-ray irradiation device 21a and a detector 21b that rotate around the test piece 1 about an axis approximately perpendicular to the table and move in the vertical direction of the table.

[0089] The resistivity measuring device 22 measures the resistivity value of the test piece 1 at every unit time. The resistivity measuring device 22 has a pair of current electrodes 22 a, 22 b, a plurality of potential electrodes 22 c (six in the example shown in FIG. 1 ), and a resistivity calculating device 22 d that calculates the resistivity value from the potential difference between the pair of potential electrodes 22 c.

[0090] The pair of current electrodes 22a, 22b are made of a metal mesh or the like that is approximately circular in a plan view. As shown in FIG. 1 , the pair of current electrodes 22a, 22b are respectively installed at both ends of the test piece 1 in the longitudinal direction, and are installed facing each other so as to cover the end faces of the test piece 1. In the present embodiment, an example has been described in which the current electrodes 22a, 22b are installed facing each other so as to cover both end faces of the test piece 1 so as to enable high-precision measurement of the resistivity value of the test piece 1. However, the shape and installation positions of the current electrodes 22a, 22b can be appropriately changed as needed. For example, the current electrodes 22a, 22b may be arranged on the outer peripheral surface near both ends of the test piece 1 and may be linearly wound around 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 measurement device 21 irradiates the cylindrical test piece 1 with X-rays from the longitudinal direction, the current electrodes 22a, 22b are less likely to affect the detection result of the amount of X-rays that have passed through the test piece 1.

[0091] The multiple potential electrodes 22c are arranged between the pair of current electrodes 22a, 22b at approximately equal intervals in the longitudinal direction of the test piece 1, and are each wrapped around the outer surface of the test piece 1 in the circumferential direction of the test piece 1. The current electrodes 22a, 22b and potential electrode 22c of the resistivity measuring device 22 penetrate the covering sheet 16 and are arranged in contact with the end face or side face of the test piece 1, and are sealed together with the test piece 1 by the covering sheet 16 and two end caps 15.

[0092] In this embodiment, the resistivity value is measured every unit time by the resistivity measuring device 22 and input to the crude oil movement amount ΔV calculation device described below. The frequency of measuring the resistivity value of the test specimen 1 can be, for example, every 5 minutes to 1 hour, and may be constant or may be varied as necessary. It is preferable that the measurement of the resistivity value of the test specimen 1 is started when the test specimen 1 is brought into contact with the low-salinity water 12c, and is ended after it is confirmed that no change in the resistivity value is observed. In other words, it is preferable that the measurement of the resistivity value of the test specimen 1 is 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 amount of crude oil to the amount of water in the test piece 1 per unit time based on the resistivity value measured per unit time of the test piece 1 and / or the X-ray CT value measured per unit time of the test piece 1, and calculates the amount of crude oil movement ΔV. The crude oil movement amount ΔV calculation device calculates the ratio of the amount of crude oil to the amount of water in the test piece 1 per unit time by inputting the signal of the X-ray CT value of the test piece 1 measured by the X-ray CT measurement device 21 and the signal of the resistivity value of the test piece 1 measured by the resistivity measurement device 22, and calculates the amount of crude oil movement ΔV based on the result. The amount of crude oil movement 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 resistivity values ​​measured per unit time of the test piece 1, or may be calculated based only on the X-ray CT values ​​measured per unit time of the test piece 1, and it is preferable that the crude oil movement amount ΔV calculation device calculates both the crude oil movement amount ΔV calculated based only on the resistivity values ​​measured per unit time of the test piece 1 and the crude oil movement amount ΔV calculated based only on the X-ray CT values ​​measured per unit time of the test piece 1, and inputs them to the evaluation device 30. This is because the evaluation device 30 can more accurately evaluate whether or not a crude oil recovery effect can be obtained.

[0096] Specifically, the following method is used to calculate the ratio of the amount of crude oil to the amount of water in the test specimen 1 per unit time from the X-ray CT values ​​of the test specimen 1. First, multiple rocks of the same type as the test specimen 1 are prepared. Then, after the voids present inside each rock are completely saturated with water, crude oil is injected into each rock at different pressures. In this way, multiple calibration curve test specimens with different water-to-crude oil mixture ratios are prepared. The water-to-crude oil mixture ratio is calculated from the porosity of the calibration curve test specimen and the densities of water and crude oil, based on the measurement results of the mass difference between the calibration curve test specimens before and after the injection of water and crude oil.

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

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

[0099] Furthermore, the method for calculating the ratio of the amount of crude oil to the amount of water in test specimen 1 per unit time from the resistivity value of test specimen 1 is specifically as follows. The resistivity values ​​of the above-mentioned test specimens for the calibration curve are measured in the same manner as the measurement of the resistivity value of test specimen 1. Using the results, a relational expression between the resistivity value and the ratio of the amount of crude oil to the amount of water is obtained. Using the relational expression thus obtained, the ratio of the amount of crude oil to the amount of water in test specimen 1 is calculated from the resistivity value of test specimen 1.

[0100] Furthermore, the method for calculating the amount of crude oil movement ΔV from the results of calculating the ratio of the amount of crude oil to the amount of water in the test piece 1 per unit time is specifically as follows: For example, after the test piece 1 is brought into contact with the low-salinity water 12c, the amount of crude oil that has decreased over time is calculated from the ratio of the amount of crude oil to the amount of water calculated from the X-ray CT value obtained by the first measurement and the ratio of the amount of crude oil to the amount of water calculated from the X-ray CT value obtained by measurement after a predetermined time has passed, and this is taken as the amount of crude oil movement ΔV that has moved from the first measurement until the predetermined time has passed.

[0101] Furthermore, for example, after the test specimen 1 is brought into contact with the low-salinity water 12c, the amount of crude oil that has decreased over time is calculated from the ratio of the amount of crude oil to the amount of water calculated from the resistivity value obtained by the initial measurement and the ratio of the amount of crude oil to the amount of water calculated from the resistivity value obtained by measurement after a predetermined time, and this is taken as the amount of crude oil that has moved from the initial measurement until the predetermined time has elapsed, ΔV.

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

[0103] (Evaluation Device) The evaluation device 30 evaluates the crude oil recovery effect due to chemical osmosis in low-salinity water flooding of the test specimen 1 based on the effective osmotic pressure ΔP and the crude oil movement amount ΔV. The evaluation device 30 determines that there is a crude oil recovery effect due to chemical osmosis in low-salinity water flooding of the test specimen 1 when at least one condition selected from the following (i) to (iii) is 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 an 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 an amount of crude oil movement ΔV can be confirmed. (iii) The effective osmotic pressure ΔP is 0, and the presence of an amount of crude oil movement ΔV can be confirmed.

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

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

[0107] However, for example, even if the effective osmotic pressure ΔP is greater than 0, the crude oil recovery effect may not be obtained, for example, if crude oil that cannot be recovered by chemical osmosis remains in the test specimen 1 even after the crude oil recovery effect due to chemical osmosis has disappeared. In this embodiment, since the crude oil recovery effect is determined to be present when either (i) or (ii) is satisfied, there is no erroneous determination that the crude oil recovery effect is present when the effective osmotic pressure ΔP is greater than 0 but the crude oil recovery effect is not obtained. Therefore, the crude oil recovery effect due to chemical osmosis in the low-salinity water flooding of the test specimen 1 can be accurately evaluated.

[0108] Furthermore, for example, if the test specimen 1 is a rock with relatively small pores, the amount of oil movement ΔV may not be measured, or the measurement error of the amount of oil movement ΔV may be large, resulting in insufficient accuracy in evaluating whether or not a crude oil recovery effect can be achieved by low-salinity water flooding. In this embodiment, since it is determined that a crude oil recovery effect exists when (i) or (ii) is satisfied, for example, even if the test specimen 1 is a rock with relatively small pores, the crude oil recovery effect due to chemical osmosis in low-salinity water flooding can be evaluated with high accuracy.

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

[0110] (When (iii) is satisfied) For example, if the test specimen is a rock with relatively large pores, even if the effective osmotic pressure ΔP is 0 (below the detection limit), chemical osmosis may occur due to the salinity difference ΔC, and a crude oil recovery effect may be obtained. In this embodiment, since it is determined that there is a crude oil recovery effect when (iii) is satisfied, there is no mistaken determination that there is no crude oil recovery effect when the crude oil recovery effect can be obtained even if the effective osmotic pressure ΔP is 0. Therefore, it is possible to accurately evaluate the crude oil recovery effect caused by chemical osmosis in low-salinity water flooding of test specimen 1.

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

[0112] In the evaluation device 30 of this embodiment, the crude oil movement amount ΔV is calculated based on the measurement results of the crude oil movement amount ΔV measurement device, which calculates the ratio of the crude oil amount to the water amount in the test piece 1 per unit time, and it is preferable that the condition (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 crude oil recovery effect due to chemical osmosis in low-salinity water flooding is being continuously obtained, and the crude oil recovery effect can be evaluated more accurately.

[0113] The evaluation device 30 in this embodiment preferably uses, as the crude oil movement amount ΔV, both the crude oil movement amount ΔV calculated based solely on the resistivity values ​​measured per unit time of the test piece 1 and the crude oil movement amount ΔV calculated based solely on the X-ray CT values ​​measured per unit time of the test piece 1. Specifically, in the above (iii), the case in which the existence of the crude oil movement amount ΔV can be confirmed is preferably a case in which the existence of both the crude oil movement amount ΔV calculated based solely on the resistivity values ​​measured per unit time of the test piece 1 and the crude oil movement amount ΔV calculated based solely on the X-ray CT values ​​measured per unit time of the test piece 1 can be confirmed. Furthermore, the case in which the crude oil movement amount ΔV changes per unit time is preferably a case in which both the crude oil movement amount ΔV calculated based solely on the resistivity values ​​measured per unit time of the test piece 1 and the crude oil movement amount ΔV calculated based solely on the X-ray CT values ​​measured per unit time of the test piece 1 change per unit time. This is because whether or not a crude oil recovery effect can be obtained can be evaluated with higher accuracy.

[0114] The evaluation device 30 in this embodiment is preferably capable of confirming that the effective osmotic pressure ΔP and the crude oil movement amount ΔV are caused by the salinity difference ΔC based on the salinity difference ΔC calculated per unit time by the salinity difference ΔC calculation device of the effective osmotic pressure ΔP measurement device 10. This is because it allows for more accurate evaluation of the crude oil recovery effect caused by chemical osmosis in low-salinity water flooding.

[0115] [Method for Evaluating Crude Oil Recovery Effect] Next, as an example of the method for evaluating the crude oil recovery effect by low-salinity water flooding of this embodiment, a case will be described in which the crude oil recovery effect resulting from chemical osmosis in low-salinity water flooding of a test specimen 1 is evaluated using the crude oil recovery effect evaluation device 100 shown in Figure 1. The method for evaluating 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, and a third step of evaluating whether or not there is a crude oil recovery effect.

[0116] (First Step) As shown in Figure 1, a test specimen 1 is prepared that is made of high-salinity water 11c and rock containing crude oil and has a generally cylindrical shape. Next, current electrodes 22a and 22b of a resistivity measuring device 22 are installed at both longitudinal ends of the test specimen 1. Furthermore, a plurality of potential electrodes 22c are wound around the pair of current electrodes 22a and 22b at approximately equal intervals in the longitudinal direction of the test specimen 1. In this way, the current electrodes 22a and 22b and the potential electrodes 22c are installed on the test specimen 1.

[0117] Thereafter, a cover sheet 16 is placed over the entire side surface of the test piece 1 on which the pair of current electrodes 22a, 22b and the plurality of potential electrodes 22c are installed. In addition, a water distribution plate 14 and an end cap 15 are placed in this order on the outside of the current electrodes 22a, 22b installed on both end surfaces of the test piece 1, and the test piece 1 on which the pair of current electrodes 22a, 22b and the plurality of potential electrodes 22c are installed is sealed by the cover sheet 16 and the end cap 15.

[0118] In this embodiment, the test specimen 1 is made of a rock collected from an oil reservoir for which the crude oil recovery effect is to be evaluated, or a rock simulating an oil reservoir, and is stored in the container 13 in a state that satisfies the following conditions (a) to (c): (a) A state in which a confining pressure simulating the geopressure of the oil reservoir is applied; (b) A state in which the test specimen is heated to a temperature simulating the geotemperature of the oil reservoir; and (c) A state in which a pore water pressure simulating the pore water pressure in the oil reservoir is applied.

[0119] That is, the sealed test specimen 1 is placed in a container 13, and the inside of the container 13 is pressurized using a pressure device (not shown), so that a confining pressure simulating the geological pressure of the oil reservoir is applied to the test specimen 1, and the test specimen 1 is heated from the outside of the container 13 using a heating device 18 to a temperature simulating the geological temperature of the oil reservoir.

[0120] 1 , high-salinity water 11c is stored in the high-salinity water storage tank 11 of the effective osmotic pressure ΔP measuring device 10, the high-salinity water storage tank 11 is pressurized by a hydraulic loading device (not shown), and the high-salinity water 11c is supplied to the test specimen 1 at a predetermined flow rate by a pump 31. Also, low-salinity water 12c is stored in the low-salinity water storage tank 12, the low-salinity water storage tank 12 is pressurized by a hydraulic loading device (not shown), and the low-salinity water 12c is supplied to the test specimen 1 at a predetermined flow rate by a pump 31. As a result, a pore water pressure simulating the pore water pressure in an oil reservoir is loaded on the test specimen 1, and the same back pressure is applied to the high-salinity water 11c contained in the water distribution plate 14, the low-salinity water 12c contained in the water distribution plate 14, and the crude oil contained in the test specimen 1. Thereafter, the application of pore water pressure to the high-salinity water storage tank 11 by the hydraulic loading device (not shown) is stopped, and the high-salinity water storage tank 11 is sealed.

[0121] Thereafter, the pump 31 supplies high-salinity water 11c from the high-salinity water storage tank 11 to the test specimen 1 via the high-salinity water supply pipe 11a and the water distribution board 14 at a substantially constant liquid flow rate, and the high-salinity water 11c is discharged from the high-salinity water discharge pipe 11b via the water distribution board 14. This causes the high-salinity water 11c in the high-salinity water storage tank 11 and the high-salinity water 11c contained in the water distribution board 14 that contacts the end face of the test specimen 1 to circulate.

[0122] Next, the pump 31 supplies low-salinity water 12c from the low-salinity water storage tank 12 to the test specimen 1 at a substantially constant liquid flow rate via the low-salinity water supply pipe 12a and the water distribution board 14, and the low-salinity water 12c is discharged from the low-salinity water discharge pipe 12b via the water distribution board 14. This brings the low-salinity water 12c into contact with the end face on the other end (the right end in FIG. 1 ) of the test specimen 1, and while maintaining constant pore water pressure at the end face on the other end of the test specimen 1, the low-salinity water 12c in the low-salinity water storage tank 12 and the low-salinity water 12c contained in the water distribution board 14 that contacts the end face of the test specimen 1 are circulated.

[0123] The pressure of the high-salinity water 11c flowing through the high-salinity water discharge pipe 11b is measured every unit time by a pressure measuring device 33 installed in the high-salinity water discharge pipe 11b. Also, the salinity of the high-salinity water 11c flowing through the high-salinity water discharge pipe 11b is measured every unit time by a salinity concentration measuring device 32 installed in the high-salinity water discharge pipe 11b.

[0124] The pressure of the low-salinity water 12c flowing through the low-salinity water discharge pipe 12b is measured every unit time by a pressure measuring device 33 installed in the low-salinity water discharge pipe 12b. The salinity of the low-salinity water 12c flowing through the low-salinity water discharge pipe 12b is measured every unit time by a salinity measuring device 32 installed in the low-salinity water discharge pipe 12b.

[0125] In the first step of this embodiment, a pressure signal of the high-salinity water 11c and a pressure signal of the low-salinity water 12c measured by the two pressure measuring devices 33 are input to an effective osmotic pressure ΔP calculating device, which calculates the effective osmotic pressure ΔP, which is the pressure difference between the high-salinity water 11c and the low-salinity water 12c, for each unit time. In the first step of this embodiment, a salt concentration signal of the high-salinity water 11c and a salt concentration signal of the low-salinity water 12c measured by the two salinity measuring devices 32 are input to a salt concentration difference ΔC calculating device, which preferably calculates the salt concentration difference ΔC between the high-salinity water 11c and the low-salinity water 12c for each unit time.

[0126] (Second Step) In this embodiment, the X-ray CT value of the test piece 1 is measured every unit time by the X-ray CT measurement device 21, and / or the resistivity value of the test piece 1 is measured every unit time by the resistivity measurement device 22.

[0127] The X-ray CT value of the test piece 1 can be measured, for example, by the following method. The X-ray irradiator 21a is moved along the length of the test piece 1 while rotating circumferentially around the test piece 1 along the side surface of the substantially cylindrical test piece 1, thereby irradiating X-rays onto the test piece 1. The detector 21b, together with the X-ray irradiator 21a, is moved along the length of the test piece 1 while rotating circumferentially around the test piece 1 along the side surface of the substantially cylindrical test piece 1, thereby detecting the amount of X-rays that have passed through the test piece 1. Thereafter, the CT value calculator 21c calculates an X-ray CT value corresponding to the density of the test piece 1 from the detection results detected by the detector 21b.

[0128] The resistivity value of the test piece 1 can be measured, for example, by applying a current from a pair of current electrodes 22a, 22b while measuring the potential difference between a pair of potential electrodes 22c selected from a plurality of potential electrodes 22c, and calculating the resistivity value from the results using a resistivity calculation device 22d.

[0129] In the second step of this embodiment, a signal of the X-ray CT value of the test piece 1 measured every unit time by the X-ray CT measurement device 21 and a signal of the resistivity value of the test piece 1 measured every unit time by the resistivity measurement device 22 are input to a crude oil movement amount ΔV measurement device. Then, the crude oil movement amount ΔV measurement device calculates the ratio of the amount of crude oil to the amount of water in the test piece 1 every unit time based on the X-ray CT value measured every unit time of the test piece 1 and / or the resistivity value measured every unit time of the test piece 1, and calculates the amount of crude oil movement ΔV based on the measurement results.

[0130] (Third Step) In the third step of this embodiment, the presence or absence of a crude oil recovery effect is evaluated by the evaluation device 30. In the third step, if at least one condition selected from the following (i) to (iii) is satisfied, it is determined that there is a crude oil recovery effect due to chemical osmosis in the low-salinity water flooding of the test specimen 1.

[0131] (i) The effective osmotic pressure ΔP is greater than 0, the effective osmotic pressure ΔP changes per unit time, and the presence of an 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 an amount of crude oil movement ΔV can be confirmed. (iii) The effective osmotic pressure ΔP is 0, and the presence of an amount of crude oil movement ΔV can be confirmed.

[0132] In this embodiment, the third step preferably satisfies the above conditions (ii) and / or (iii) and the crude oil movement amount ΔV changes per unit time, because this allows prediction of whether the crude oil recovery effect resulting from chemical osmosis in low-salinity water flooding is being continuously obtained, and allows for more accurate evaluation of the crude oil recovery effect.

[0133] The crude oil recovery effect evaluation device 100 of this embodiment includes an effective osmotic pressure ΔP measurement device 10 that calculates the effective osmotic pressure ΔP per unit time, a crude oil movement amount ΔV measurement device that calculates the crude oil movement amount ΔV caused by chemical osmosis caused by the salinity difference ΔC, and calculates the crude oil movement amount ΔV based on the measurement results that calculate the ratio of the crude oil amount to the water amount in the test piece 1 per unit time, and an evaluation device 30 that evaluates the presence or absence of a crude oil recovery effect.The evaluation device 30 determines that there is a crude oil recovery effect caused by chemical osmosis in the low-salinity water flooding of the test piece 1 when at least one condition selected from the above (i) to (iii) is satisfied.

[0134] The method for evaluating the effectiveness of crude oil recovery according to this embodiment includes a first step of calculating the effective osmotic pressure ΔP for each unit time, a second step of calculating the amount of crude oil movement ΔV based on the measurement results of the ratio of the amount of crude oil to the amount of water in the test specimen 1 for each unit time, and a third step of evaluating whether or not there is an oil recovery effect. If at least one condition selected from the above (i) to (iii) is satisfied in the third step, it is determined that there is an oil recovery effect due to chemical osmosis in the low-salinity water flooding of the test specimen 1.

[0135] Therefore, by using the crude oil recovery effect evaluation device 100 and evaluation method of this embodiment, it is possible to evaluate with high accuracy whether or not a crude oil recovery effect due to chemical infiltration in a low-salinity water flooding can be obtained for a test specimen 1 consisting of high-salinity water and rock containing crude oil. Furthermore, in the crude oil recovery effect evaluation device 100 and evaluation method of this embodiment, if rock collected from an oil reservoir from which crude oil is to be recovered or a rock simulating an oil reservoir from which crude oil is to be recovered is used as the test specimen 1, it can be used, for example, to predict the amount of crude oil recovered when crude oil remaining in an oil reservoir is recovered by a low-salinity water flooding, which is preferable.

[0136] In the present embodiment, as an example of a preferred evaluation method, a case has been described in which the test specimen 1 is contained in the container 13 in a state in which all of the following conditions (a) to (c) are satisfied. However, the test specimen 1 may also be contained in the container 13 in a state in which the following conditions (a) and (b) are satisfied but the following condition (c) is not satisfied, or in a state in which the following conditions (a) and (c) are satisfied but the following condition (b) is not satisfied: (a) A state in which a confining pressure simulating the geopressure of the oil reservoir is applied; (b) A state in which the test specimen 1 is heated to a temperature simulating the geothermal temperature of the oil reservoir; and (c) A state in which a pore water pressure simulating the pore water pressure in the oil reservoir is applied.

[0137] Second Embodiment Figure 2 is a schematic diagram illustrating an evaluation device 200 for evaluating the effectiveness of crude oil recovery due to chemical osmosis in a low-salinity water flooding process according to a second embodiment. The evaluation device 200 of this embodiment differs from the evaluation device 100 of the first embodiment shown in Figure 1 in that the effective osmotic pressure ΔP measurement device 10 of the evaluation device 100 of the first embodiment does not include the high-salinity water storage tank 11, the high-salinity water supply pipe 11a, the high-salinity water discharge pipe 11b, and the pump 31 installed in the high-salinity water supply pipe 11a. The water distribution plate 14 is not provided on the surface of the end cap 15 located on one end (the left end in Figure 2) of the test specimen 1 facing the test specimen 1, but instead includes a salinity measurement device 32 and a pressure measurement device 33. In the evaluation device 200 of this embodiment shown in Figure 2, the same components as those of the evaluation device 100 of the first embodiment shown in Figure 1 are designated by the same reference numerals, and their description will be omitted.

[0138] In the evaluation device 200 shown in FIG. 2 , a device for pressurizing the low-salinity water storage tank 12, which stores the low-salinity water 12c to be supplied to the test specimen 1, can be used as the hydraulic loading device. In the evaluation device 200 shown in FIG. 2 , a water distribution plate 14 is not provided on the end face of one end (the left end in FIG. 2 ) of the test specimen 1, and the high-salinity water 11c in the high-salinity water storage tank 11 and the high-salinity water 11c present on the end face of one end of the test specimen 1 are not circulated. The pressure of the high-salinity water 11c is measured every unit time by a pressure measuring device 33 installed on the surface of the end cap 15 facing the test specimen 1. The salinity of the high-salinity water 11c is also measured every unit time by a salinity measuring device 32 installed on the surface of the end cap 15 facing the test specimen 1.

[0139] In the evaluation device 200 shown in Fig. 2, high-salinity water 11c is not supplied to the test specimen 1, and only the high-salinity water 11c contained in the test specimen 1 is used as the high-salinity water 11c. Therefore, by using the evaluation device 200 shown in Fig. 2, the crude oil recovery effect due to chemical osmosis in low-salinity water flooding on the test specimen 1 can be evaluated with high accuracy under conditions that are more realistic than when the evaluation device 100 of the first embodiment shown in Fig. 1 is used.

[0140] <Third Embodiment> Figure 3 is a schematic diagram for explaining an evaluation device 300 for evaluating the effect of crude oil recovery due to chemical osmosis in a low-salinity water flooding method according to a third embodiment. The evaluation device 300 of this embodiment differs from the evaluation device 100 of the first embodiment shown in Figure 1 in that the test specimen 1 comes into contact with rock 1a containing low-salinity water 12c, thereby bringing the test specimen 1 into contact with the low-salinity water 12c. In the evaluation device 300 of this embodiment shown in Figure 3, the same components as those in the evaluation device 100 of the first embodiment shown in Figure 1 are designated by the same reference numerals, and their description will be omitted.

[0141] Similar to the test specimen 1 in the first embodiment shown in FIG. 1 , the test specimen 1 shown in FIG. 3 is made of high-salinity water 11c and rock containing crude oil and has a generally cylindrical shape. Unlike the first embodiment, one end face of the test specimen 1 (the right end in FIG. 3 ) is in contact with a rock 1a containing low-salinity water 12c, which has a generally cylindrical shape and is coaxial with the test specimen 1 and has approximately the same diameter. As shown in FIG. 3 , the test specimen 1 and rock 1a are integrated, and current electrodes 22a, 22b and a water distribution basin 14 are installed on both end faces of the integrated structure, respectively, and multiple potential electrodes 22c are installed on the side faces. The integrated test specimen 1 and rock 1a are sealed by a cover sheet 16 covering the entire side surfaces of the test specimen 1 and rock 1a and two end caps 15 arranged opposite each other on the outside of the water distribution basin 14.

[0142] The rock 1a may be any rock containing low-salinity water 12c, and may be the same rock type as the test specimen 1 or a different rock type from the test specimen 1. The rock 1a is preferably a rock with a larger porosity and / or pore size than the test specimen 1. This is because the oil recovery effect due to chemical infiltration can be evaluated under more realistic conditions.

[0143] In the evaluation device 300 shown in Figure 3, a pump 31 supplies low-salinity water 12c from the low-salinity water storage tank 12 to a water distribution basin 14 that contacts the end face of the rock 1a containing the low-salinity water 12c at a substantially constant liquid flow rate, and the low-salinity water 12c in the low-salinity water storage tank 12 and the low-salinity water 12c contained in the rock 1a are circulated.

[0144] In the evaluation device 300 shown in Fig. 3, the test specimen 1, which is made of high-salinity water 11c and rock containing crude oil, comes into contact with rock 1a containing low-salinity water 12c, thereby coming into contact with the low-salinity water 12c. Therefore, when using the evaluation device 300 shown in Fig. 3, the test specimen 1 can be evaluated under conditions that more closely match the state of the test specimen 1 in an oil reservoir, compared to when using the evaluation device 100 of the first embodiment shown in Fig. 1, and the crude oil recovery effect due to chemical infiltration in a low-salinity water flooding of the test specimen 1 can be evaluated with high accuracy under conditions that are more realistic.

[0145] <Fourth Embodiment> Figure 4 is a schematic diagram illustrating an evaluation device 400 for evaluating the crude oil recovery effect due to chemical osmosis in a low-salinity water flooding process according to a fourth embodiment. The evaluation device 400 of this embodiment differs from the evaluation device 300 of the third embodiment shown in Figure 3 in that the effective osmotic pressure ΔP measurement device 10 of the evaluation device 300 of the third embodiment does not include the high-salinity water storage tank 11, the high-salinity water supply pipe 11a, the high-salinity water discharge pipe 11b, and the pump 31 installed in the high-salinity water supply pipe 11a, and the end cap 15 located on one end (the left end in Figure 4) of the test specimen 1 does not include the water distribution plate 14 on the surface of the end cap 15 facing the test specimen 1, but instead includes a salinity measurement device 32 and a pressure measurement device 33. In the evaluation device 400 of this embodiment shown in Figure 4, the same components as those of the evaluation device 300 of the third embodiment shown in Figure 3 are designated by the same reference numerals, and their description will be omitted.

[0146] In the evaluation device 400 shown in FIG. 4 , similar to the evaluation device 200 shown in FIG. 2 , a device for pressurizing the low-salinity water storage tank 12, which stores the low-salinity water 12c to be supplied to the test specimen 1, can be used as the hydraulic loading device. In the evaluation device 400 shown in FIG. 4 , similar to the evaluation device 200 shown in FIG. 2 , a water distribution plate 14 is not provided on the end face of one end (the left end in FIG. 2 ) of the test specimen 1, and the high-salinity water 11c in the high-salinity water storage tank 11 and the high-salinity water 11c present on the end face of one end of the test specimen 1 are not circulated. The pressure of the high-salinity water 11c is measured every unit time by a pressure measuring device 33 installed on the surface of the end cap 15 facing the test specimen 1. The salinity of the high-salinity water 11c is also measured every unit time by a salinity measuring device 32 installed on the surface of the end cap 15 facing the test specimen 1.

[0147] In the evaluation device 400 shown in FIG. 4, similar to the evaluation device 300 shown in FIG. 3, the test specimen 1, which is composed of rock containing high-salinity water 11c and crude oil, comes into contact with rock 1a containing low-salinity water 12c, thereby coming into contact with the low-salinity water 12c. Furthermore, similar to the evaluation device 200 shown in FIG. 2, the evaluation device 400 shown in FIG. 4 does not supply high-salinity water 11c to the test specimen 1, but instead uses only the high-salinity water 11c contained in the test specimen 1 as the high-salinity water 11c. Therefore, when using the evaluation device 400 shown in FIG. 4, the test specimen 1 can be evaluated under conditions that are more consistent with the state of the test specimen 1 in an oil reservoir, compared to the evaluation devices 100, 200, and 300 of the first to third embodiments. This allows the crude oil recovery effect due to chemical osmosis in a low-salinity water flooding of the test specimen 1 to be evaluated with high accuracy under more realistic conditions.

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

[0149] 5, the evaluation device 500 is provided with a hydraulic loading device, which includes pipes and valves 19 connected to two end caps 15. In the fifth embodiment, in the first step of calculating the effective seepage pressure ΔP per unit time, the integrated test specimen 1 and rock 1a are placed in a container 13, a pressure device (not shown) is used to load a confining pressure simulating the geopressure of an oil reservoir onto the test specimen 1, and a heating device 18 is used to heat the test specimen 1 to a temperature simulating the geothermal temperature of the oil reservoir, and then the following operations are performed.

[0150] That is, the valve 19 located on the rock 1a side is opened, and low-salinity water 12c is supplied to the rock 1a at a predetermined pressure via a pipe connected to the end cap 15 by a known method. The valve 19 located on the test specimen 1 side is also opened, and high-salinity water 11c is supplied to the test specimen 1 at a predetermined pressure via a pipe connected to the end cap 15 by a known method. By performing these operations, a pore water pressure simulating the pore water pressure in an oil reservoir is applied to the test specimen 1, and the same back pressure is applied to the high-salinity water 11c contained in the water distribution basin 14 at one end (the left end in FIG. 5 ), the low-salinity water 12c contained in the water distribution basin 14 at the other end (the right end in FIG. 5 ), and the crude oil contained in the test specimen 1. Then, the two valves 19 are closed to stop the application of pore water pressure from the pipes connected to the end caps 15 to the water distribution basins 14 located at both ends of the test specimen 1.

[0151] 5, the high-salinity water 11c contained in the test specimen 1 is not circulated. Therefore, by closing the two valves 19, back pressure is maintained within the test specimen 1 and the rock 1a. The pressure of the low-salinity water 12c is measured every unit time by a pressure measuring device 33 installed on the surface of the end cap 15 facing the rock 1a. In addition, the salinity of the low-salinity water 12c is measured every unit time by a salinity measuring device 32 installed on the surface of the end cap 15 facing the rock 1a.

[0152] 5, the low-salinity water 12c is not supplied to the rock 1a, and only the low-salinity water 12c contained in the rock 1a is used as the low-salinity water 12c. Therefore, the evaluation device 500 shown in FIG. 5 can evaluate the crude oil recovery effect due to chemical osmosis in the low-salinity water flooding of the test specimen 1 without using the low-salinity water storage tank 12, the pump 31, etc.

[0153] 4, the evaluation device 500 shown in FIG. 5 includes a test specimen 1 made of rock containing high-salinity water 11c and crude oil, which is brought into contact with rock 1a containing low-salinity water 12c, thereby contacting the low-salinity water 12c. Furthermore, the high-salinity water 11c is not supplied to the test specimen 1, and only the high-salinity water 11c contained in the test specimen 1 is used as the high-salinity water 11c. Therefore, when using the evaluation device 500 shown in FIG. 5, the test specimen 1 can be evaluated under conditions that more closely match the state of the test specimen 1 in an oil reservoir, similar to the evaluation device 400 shown in FIG. 4. Therefore, the crude oil recovery effect due to chemical infiltration in a low-salinity water flooding of the test specimen 1 can be evaluated with high accuracy under more realistic conditions.

[0154] Sixth Embodiment Figure 6 is a schematic diagram illustrating an evaluation device 600 for evaluating the effect of crude oil recovery due to chemical osmosis in a low-salinity water flooding method according to a sixth embodiment. The evaluation device 600 of this embodiment differs from the evaluation device 100 of the first embodiment shown in Figure 1 in that it does not include a container 13 for accommodating the test specimen 1, a pressurizing device, a heating device 18, or a hydraulic loading device. Instead, the test specimen 1, current electrodes 22a and 22b disposed at both ends of the test specimen 1, a water distribution 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 of the test specimen 1. In the evaluation device 600 of this embodiment shown in Figure 6, the same components as those in the evaluation device 100 of the first embodiment shown in Figure 1 are designated by the same reference numerals, and their description will be omitted.

[0155] The resin coating layer 17 may consist of one resin layer or two or more resin layers. When the resin coating layer 17 consists of two resin layers, it is preferable that the resin coating layer 17 consists of, for example, a substantially cylindrical outer layer made of acrylic resin or the like and an inner layer made of silicone resin and / or epoxy resin or the like filled into the outer layer. This is because such a resin coating layer 17 can be easily manufactured by the method described below.

[0156] First, a substantially cylindrical pipe made of a resin material that will form the outer layer is prepared. Next, the test specimen 1, wrapped around the potential electrode 22c, is placed inside the pipe. The current electrodes 22a and 22b, the water distribution plate 14, and the end cap 15 are then placed on both ends of the test specimen 1, in that order, and then placed inside the pipe. A resin composition containing the resin material that will form the inner layer is then filled between the inner wall of the pipe and the components using a known method, and then cured. Through these steps, a resin coating layer 17 consisting of two resin layers, an outer layer and an inner layer, can be formed.

[0157] 6 does not have a container 13 for accommodating the test specimen 1, a pressurizing device, a heating device 18, or a hydraulic loading device, but has a resin coating layer 17, and therefore can be manufactured more easily than the evaluation devices 100, 200, 300, 400, and 500 of the first to fifth embodiments. Furthermore, by using the evaluation device 600 of this embodiment, the crude oil recovery effect resulting from chemical osmosis in a low-salinity water flood on the test specimen 1 can be easily evaluated.

[0158] Furthermore, the evaluation device 600 shown in FIG. 6 uses transparent or semi-transparent end caps 15, allowing both end faces of the test specimen 1 to be visually observed. In this case, the crude oil recovery effect can be evaluated by visually observing the seepage of oil from the end faces of the test specimen 1, which is preferable. In particular, when the evaluation device does not include a resistivity measuring device 22, or when the current electrodes 22a, 22b are arranged on the outer peripheral surface near both ends of the test specimen 1 and are linearly wound around the outer surface of the test specimen 1 in the circumferential direction of the test specimen 1, the end caps 15 and the test specimen 1 are arranged in contact with each other. This makes it easier to visually observe the end faces of the test specimen 1, which is preferable.

[0159] Seventh Embodiment In the first to sixth embodiments described above, the crude oil movement amount ΔV is calculated based on measurement results of the ratio of the amount of crude oil to the amount of water in the test specimen 1 calculated per unit time. However, the crude oil movement amount ΔV may also be calculated based on measurement results of the amount of crude oil that seeped out of the test specimen 1 in contact with the low-salinity water 12c. In this case, it is preferable to calculate the crude oil movement amount ΔV based on measurement results of the amount of crude oil that seeped out of the test specimen 1 in contact with the low-salinity water 12c per unit time. In the seventh embodiment, a case will be described in which the crude oil movement amount ΔV is calculated based on measurement results of the amount of crude oil that seeped out of the test specimen 1 in contact with the low-salinity water 12c.

[0160] [Apparatus for evaluating crude oil recovery effect] The apparatus for evaluating crude oil recovery effect in the seventh embodiment has the same effective osmotic pressure ΔP measuring device 10 as the apparatus for evaluating crude oil recovery effect 100 in the first embodiment shown in Fig. 1. Furthermore, unlike the first embodiment, the apparatus for evaluating crude oil recovery effect in the seventh embodiment uses the following as a crude oil movement amount ΔV measuring device and evaluation device.

[0161] (Crude Oil Movement Amount ΔV Measuring Device) In the seventh embodiment, the crude oil movement amount ΔV measuring device used includes an oil-water separation pot (not shown) connected to the low-salinity 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) that measures the volume of the oil (crude oil) layer separated in the oil-water separation pot, and a crude oil amount calculating means (not shown) that calculates the crude oil movement amount ΔV. In this embodiment, an example will be described in which the oil-water separation pot is connected to the low-salinity water discharge pipe 12b, but the oil-water separation pot may also be connected to the low-salinity water storage tank 12.

[0162] In this embodiment, when the crude oil movement amount ΔV measuring device calculates the crude oil movement amount ΔV based on the measurement results of the amount of crude oil seeping out from the test piece 1 in contact with the low salinity water 12c per unit time, multiple oil-water separation pots are prepared, and the oil-water separation pots connected to the low salinity water discharge pipe 12b are replaced per unit time.

[0163] The crude oil amount calculation means in this embodiment receives input of the volume of the test piece 1 and the volume of crude oil measured by the crude oil volume measurement means, and calculates the ratio of the volume of recovered crude oil to the volume of the test piece 1, and inputs this as the crude oil movement amount ΔV to the evaluation device. When the crude oil movement amount ΔV measurement device calculates the crude oil movement amount ΔV based on the measurement results obtained by calculating the amount of crude oil seeping out from the test piece 1 per unit time, the crude oil amount calculation means calculates the ratio of the volume of recovered crude oil to the volume of the test piece 1 per unit time, and inputs this as the crude oil movement amount ΔV 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 due to chemical osmosis in the low-salinity water flooding of the test specimen 1 based on the effective osmotic pressure ΔP and the crude oil movement amount ΔV. Similar to the first embodiment, the evaluation device 30 determines that there is a crude oil recovery effect due to chemical osmosis in the low-salinity water flooding of the test specimen 1 when at least one condition selected from the above-mentioned (i) to (iii) is satisfied.

[0165] The evaluation device 30 in this embodiment calculates the crude oil movement amount ΔV based on the measurement results obtained by the crude oil movement amount ΔV measurement device calculating the amount of crude oil seeping out from the test piece 1 in contact with the low-salinity water 12c per unit time, and 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 resulting from chemical osmosis in low-salinity water flooding is being continuously obtained, and the crude oil recovery effect can be evaluated more accurately.

[0166] [Method for Evaluating Crude Oil Recovery Effect] In the method for evaluating crude oil recovery effect in the seventh embodiment, the first and third steps are performed in the same manner as in the first embodiment. Moreover, in the seventh embodiment, unlike the first embodiment, the following step is performed as the second step.

[0167] (Second Step) In the first step, the test specimen 1 containing the high-salinity water 11c and crude oil is brought into contact with the low-salinity water 12c. The low-salinity water 12c in the low-salinity water storage tank 12, the low-salinity water supply pipe 12a, and the low-salinity water discharge pipe 12b is then placed in an oil-water separation pot connected to the low-salinity water discharge pipe 12b. Next, the low-salinity water 12c placed in the oil-water separation pot is separated into an oil (crude oil) layer and a water layer in the oil-water separation pot. The volume of the oil (crude oil) layer separated in the oil-water separation pot is then measured using a crude oil volume measuring means.

[0168] Thereafter, the crude oil volume calculation means calculates the ratio of the volume of the recovered crude oil to the volume of the test body 1 from the volume of the test body 1 and the volume of the crude oil measured by the crude oil volume measurement means, and inputs this as the crude oil movement amount ΔV into the evaluation device.

[0169] When the crude oil movement amount ΔV measurement device calculates the crude oil movement amount ΔV based on the measurement results of the amount of crude oil seeping out from the test piece 1 per unit time, in the second step, the first and second operations shown below are repeatedly performed.

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

[0171] (Second operation) The oil-water separation pot not containing the low-salinity water 12c is connected to the low-salinity water discharge pipe 12b, the low-salinity water 12c is again placed in the low-salinity water storage tank 12, and the low-salinity water 12c in the low-salinity water storage tank 12 is circulated with the low-salinity water 12c to be brought into contact with the end surface of the test specimen 1. In this way, the low-salinity water 12c is brought into contact with the end surface on the other end side (the end on the right side in FIG. 1 ) of the test specimen 1.

[0172] Thereafter, the low-salinity water 12c contained in each oil-water separation pot is 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 a crude oil volume measuring means. Thereafter, the crude oil amount calculating means calculates the ratio of the volume of recovered crude oil to the volume of the test piece 1 per unit time from the time that the test piece 1 was in contact with the low-salinity water 12c, the volume of the test piece 1, and the volume of crude oil measured by the crude oil volume measuring means, and inputs this as the crude oil movement amount ΔV into the evaluation device.

[0173] The crude oil recovery effect evaluation device of this embodiment includes an effective osmotic pressure ΔP measurement device 10 that calculates the effective osmotic pressure ΔP per unit time, a crude oil movement amount ΔV measurement device that calculates the crude oil movement amount ΔV caused by the salinity difference ΔC and calculates the crude oil movement amount ΔV based on the measurement results of the amount of crude oil seeping out from the test piece 1 in contact with the low-salinity water 12c, and an evaluation device 30 that evaluates the presence or absence of a crude oil recovery effect. If the evaluation device 30 satisfies at least one condition selected from the above (i) to (iii), it is determined that there is a crude oil recovery effect due to chemical osmosis in the low-salinity water flooding of the test piece 1.

[0174] The method for evaluating the effectiveness of crude oil recovery according to this embodiment includes a first step of calculating the effective osmotic pressure ΔP per unit time, a second step of calculating the amount of crude oil movement ΔV based on the measurement results of the amount of crude oil seeping from the test specimen 1 in contact with the low-salinity water 12c, and a third step of evaluating whether or not there is an oil recovery effect. If at least one condition selected from the above (i) to (iii) is satisfied in the third step, it is determined that there is an oil recovery effect due to chemical osmosis in the low-salinity water flooding for the test specimen 1. Therefore, by using the device and method for evaluating the effectiveness of crude oil recovery according to this embodiment, it is possible to evaluate with high accuracy whether or not there is an oil recovery effect due to chemical osmosis in the low-salinity water flooding for the test specimen 1, which is made of high-salinity water and rock containing crude oil.

[0175] Eighth Embodiment In the first to sixth embodiments described above, the crude oil movement amount ΔV is calculated based on measurement results of the ratio of the amount of crude oil to the amount of water in the test specimen 1 calculated per unit time. However, the crude oil movement amount ΔV may also be calculated based on measurement results of the mass difference of the test specimen 1 before contacting the test specimen 1 with the low-salinity water 12c (or contacting the test specimen 1 with rock 1a containing the low-salinity water 12c, thereby bringing the test specimen 1 into contact with the low-salinity water 12c) and after contacting the test specimen 1 with the low-salinity water 12c. In this case, the crude oil movement amount ΔV may also be calculated based on measurement results of the mass difference of the test specimen 1 before contacting the test specimen 1 with the low-salinity water 12c (or contacting the test specimen 1 with rock 1a containing the low-salinity water 12c, thereby bringing the test specimen 1 into contact with the low-salinity water 12c) and after contacting the test specimen 1 with the low-salinity water 12c, calculated per unit time. In the eighth embodiment, a case will be described in which the crude oil movement amount ΔV is calculated based on the measurement results of the mass difference of the above-mentioned test piece 1.

[0176] [Apparatus for evaluating crude oil recovery effect] The apparatus for evaluating crude oil recovery effect in the eighth embodiment has the same effective osmotic pressure ΔP measuring device 10 as the apparatus for evaluating crude oil recovery effect 100 in the first embodiment shown in Fig. 1. Furthermore, unlike the first embodiment, the apparatus for evaluating crude oil recovery effect in the eighth embodiment uses the following as a crude oil movement amount ΔV measuring device and evaluation device.

[0177] (Crude oil movement amount ΔV measuring device) In the eighth embodiment, a crude oil movement amount ΔV measuring device is used that has a mass measuring device (not shown) that measures the mass of the test specimen 1 consisting of high salinity water 11c and rock containing crude oil, and a crude oil amount calculating means (not shown) that calculates the crude oil movement amount ΔV.

[0178] In the eighth embodiment, an example will be given in which a mass measuring device is used to measure the mass of a test specimen 1 consisting of high-salinity water 11c and rock containing crude oil. However, if the evaluation method for test specimen 1 is a method that does not use rock 1a containing low-salinity water 12c, a mass measuring device that measures the mass of a test specimen unit including test specimen 1 as shown below may also be used.

[0179] The test specimen unit is composed of the test specimen 1 and members integrated with the test specimen 1. In the test specimen unit, the members integrated with the test specimen 1 may be members made of a material that does not change in mass when brought into contact with the low-salinity water 12c together with the test specimen 1, and examples of such members include the current electrodes 22a, 22b and potential electrode 22c of the resistivity measuring device 22, the covering sheet 16 or resin covering layer 17, the water dividing board 14, and the end cap 15.

[0180] An example of a test specimen unit is one in which the test specimen 1, together with the water distribution plate 14 and the current electrodes 22a, 22b and potential electrode 22c of the resistivity measuring device 22, are sealed by a covering sheet 16 or a resin covering layer 17 and two end caps 15.

[0181] The crude oil amount calculation means receives the mass of the test specimen 1 before contacting it with the low-salinity water 12c and the mass of the test specimen 1 after contacting it with the low-salinity water 12c, as measured by the mass measuring device, and calculates the mass difference of the test specimen 1 before contacting it with the low-salinity water 12c and after contacting it with the low-salinity water 12c, and inputs this as the crude oil movement amount ΔV into the evaluation device.

[0182] When the crude oil migration amount ΔV measurement device calculates the crude oil migration amount ΔV based on the measurement results of the mass difference of the test specimen 1 before and after contact with the low-salinity water 12c per unit time, the crude oil amount calculation means calculates the mass difference of the test specimen 1 before and after contact with the low-salinity water 12c per unit time and inputs the calculated mass difference to the evaluation device as the crude oil migration amount ΔV. In this case, it is preferable that the mass measurement device measures the mass of the test specimen unit described above. This is because the change in mass of the test specimen 1 can be easily measured without removing the test specimen 1, which is sealed by the covering sheet 16 or resin covering 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 due to chemical osmosis in the low-salinity water flooding of the test specimen 1 based on the effective osmotic pressure ΔP and the crude oil movement amount ΔV. Similar to the first embodiment, the evaluation device 30 determines that there is a crude oil recovery effect due to chemical osmosis in the low-salinity water flooding of the test specimen 1 when at least one condition selected from the above-mentioned (i) to (iii) is satisfied.

[0184] In the evaluation device 30 of this embodiment, the crude oil movement amount ΔV measurement device calculates the crude oil movement amount ΔV based on the measurement results of the difference in mass of the test specimen 1 before and after contacting the test specimen 1 with the low-salinity water 12c per unit time, and 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 flooding is being continuously obtained, and the crude oil recovery effect can be evaluated more accurately.

[0185] [Method for Evaluating Crude Oil Recovery Effect] In the method for evaluating crude oil recovery effect in the eighth embodiment, the mass of the test piece 1 is measured using a mass measuring device before the first step is performed. Thereafter, the first step and the third step are performed in the same manner as in the first embodiment. Furthermore, in the eighth embodiment, unlike the first embodiment, the following step is performed as the second step.

[0186] (Second Step) In the first step, the test specimen 1 containing the high-salinity water 11c and crude oil is brought into contact with the low-salinity water 12c, and then the test specimen 1, which is sealed by the covering sheet 16 or resin covering layer 17 and the two end caps 15, is removed and the mass of the test specimen 1 is measured using a mass measuring device. Then, from the mass of the test specimen 1 measured before the first step and the mass of the test specimen 1 after contacting with the low-salinity water 12c, the crude oil amount calculation means calculates the mass difference of the test specimen 1 before and after contacting with the low-salinity water 12c, and inputs this to the evaluation device as the crude oil movement amount ΔV.

[0187] When the crude oil movement amount ΔV measurement device calculates the difference in mass of the test piece 1 per unit time between before contacting the test piece 1 with the low-salinity water 12c and after contacting the test piece 1 with the low-salinity water 12c, the mass of the test piece unit described above is measured by the mass measurement device before contacting the low-salinity water 12c with the end face of the test piece 1 in the first step. Then, in the second step, the first and second operations described below are repeatedly performed.

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

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

[0190] Thereafter, from the mass of the test specimen unit measured before the end face of the test specimen 1 is brought into contact with the low-salinity water 12c in the first step, the time during which the test specimen 1 is brought into contact with the low-salinity water 12c, and the mass of the test specimen unit measured in the first operation, the crude oil amount calculation means calculates the difference in mass of the test specimen 1 before and after contact with the low-salinity water 12c per unit time, and inputs this as the crude oil movement amount ΔV into the evaluation device.

[0191] The crude oil recovery effect evaluation device of this embodiment includes an effective osmotic pressure ΔP measurement device 10 that calculates the effective osmotic pressure ΔP per unit time, a crude oil movement amount ΔV measurement device that calculates the crude oil movement amount ΔV caused by the salinity difference ΔC, and calculates the crude oil movement amount ΔV based on the measurement results of the mass difference of the test specimen 1 before and after contacting the test specimen 1 with the low-salinity water 12c, and an evaluation device 30 that evaluates the presence or absence of a crude oil recovery effect. If the evaluation device 30 satisfies at least one condition selected from the above (i) to (iii), it is determined that there is a crude oil recovery effect due to chemical osmosis in the low-salinity water flooding of the test specimen 1.

[0192] The method for evaluating the effectiveness of crude oil recovery according to this embodiment includes a first step of calculating the effective osmotic pressure ΔP per unit time, a second step of calculating the amount of crude oil movement ΔV based on the measurement results of the difference in mass of the test specimen 1 before and after contacting the test specimen 1 with the low-salinity water 12c, and a third step of evaluating whether or not a crude oil recovery effect is achieved. If at least one condition selected from the above (i) to (iii) is satisfied in the third step, it is determined that a crude oil recovery effect due to chemical osmosis in a low-salinity water flooding method is achieved for the test specimen 1. Therefore, by using the device and method for evaluating the effectiveness of crude oil recovery according to this embodiment, it is possible to accurately evaluate whether or not a crude oil recovery effect due to chemical osmosis in a low-salinity water flooding method is achieved for a test specimen 1 made of high-salinity water and rock containing crude oil.

[0193] The above describes the embodiments of the present invention in detail with reference to the drawings. However, each configuration and combination thereof in each embodiment is an example, and additions, omissions, substitutions, and other modifications of the configurations are possible within the scope that does not deviate from the spirit of the present invention.

[0194] According to the present invention, it is possible to evaluate with high accuracy whether a crude oil recovery effect due to chemical permeation in a low-salinity water flood can be achieved for a test specimen made of rock. Therefore, according to the present invention, by using rock collected from an oil reservoir that is the target of crude oil recovery as a test specimen and evaluating the crude oil recovery effect due to chemical permeation in a low-salinity water flood, it is possible to evaluate with high accuracy whether a crude oil recovery effect can be achieved when crude oil remaining in the oil reservoir is recovered by a low-salinity water flood. Therefore, the present invention contributes to improving the crude oil recovery rate from oil reservoirs contained in underground rock.

[0195] 1...Test specimen, 10...Effective osmotic pressure ΔP measuring device, 11a...High-salinity water supply pipe, 11b...High-salinity water discharge pipe, 11c...High-salinity water, 12a...Low-salinity water supply pipe, 12b...Low-salinity water discharge pipe, 12c...Low-salinity water, 13...Container, 14...Water distribution plate, 15...End cap, 16...Covering sheet, 17...Resin coating layer, 18...Heating device, 19...Valve, 21...X-ray CT measurement device, 21a...X-ray irradiation device, 21b...Detector, 21c...CT value calculation device, 22...Specific resistance measurement 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

1. An effective osmotic pressure ΔP measuring device that measures the pressure of the high-salt-concentration water and the pressure of the low-salt-concentration water per unit time in a test body composed of rock containing high-salt-concentration water and crude oil and in contact with low-salt-concentration water having a second salt concentration less than the first salt concentration, 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; a device 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 calculates the amount of crude oil movement ΔV based on at least one measurement result selected from the following (1) to (3): an amount of crude oil movement ΔV measuring device; an evaluation device for evaluating the presence or absence of a crude oil recovery effect, and when at least one condition selected from the following (i) to (iii) is satisfied, it is determined that there is a crude oil recovery effect due to chemical osmosis in the low-salt-concentration water attack method on the test body: an evaluation device for evaluating the crude oil recovery effect, including: (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 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.

2. The evaluation device for evaluating the crude oil recovery effect according to claim 1, wherein the amount of crude oil movement ΔV measuring device has 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 amount of crude oil movement ΔV calculating device that calculates the ratio of the amount of crude oil and 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.

3. The evaluation device for evaluating the crude oil recovery effect according to claim 1, wherein the amount of crude oil movement ΔV measuring device calculates the amount of crude oil movement ΔV based on the measurement result of (1).

4. The evaluation device for crude oil recovery effect according to claim 1, wherein the test body contacts the rock containing the low-salt concentration water, 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, and includes at least one of the following devices: a pressurizing device having a container for accommodating the test body and applying a confinement pressure simulating the formation pressure of the oil reservoir layer to the test body accommodated in the container; a heating device having a container for accommodating the test body and heating the test body accommodated in the container to a temperature simulating the formation temperature of the oil reservoir layer; and a water pressure loading device having a container for accommodating the test body and applying a pore water pressure simulating the pore water pressure in the oil reservoir layer to the test body accommodated in the container. The evaluation device for crude oil recovery effect according to claim 1.

6. A test body composed of rock containing high-salinity water with a first salinity concentration and crude oil, and in contact with low-salinity water having a second salinity concentration less than the first salinity concentration, measures the pressure of the high-salinity water and the pressure of the low-salinity water in the test body per unit time, 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 in a first step; a step of calculating the amount of crude oil movement ΔV generated by the salinity concentration difference ΔC between the first salinity concentration and the second salinity concentration, and calculating the amount of crude oil movement ΔV based on at least one measurement result selected from the following (1) to (3) in a second step; and a 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-salinity water attack method on the test body when at least one condition selected from the following (i) to (iii) is satisfied in a third step. The evaluation method of the crude oil recovery effect includes: (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-salinity water; (3) a measurement result of the mass difference of the test body before contacting the test body with the low-salinity water and after contacting the test body with the low-salinity 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.

7. The evaluation method of the crude oil recovery effect according to claim 6, wherein in the second step, the X-ray CT value of the test body is measured per unit time by an X-ray CT measuring device and / or the specific resistance value of the test body 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 body and / or the specific resistance value measured per unit time of the test body, the ratio of the amount of crude oil and the amount of water in the test body is calculated per unit time.

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

9. The method for evaluating the crude oil recovery effect according to claim 6, wherein the test body contacts the rock containing the low-salt-concentration water, and thus is in contact with the low-salt-concentration water.

10. The method for evaluating the crude oil recovery effect according to claim 6, wherein 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, and is accommodated in a container in a state satisfying at least one condition selected from the following (a) to (c): (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.

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