Method and device for evaluating oil quantity and mobility of shale oil

Abstract

The invention provides a shale oil mass and mobility evaluation method and device, and belongs to the technical field of oil exploitation and geological and mining exploration and development. The method comprises the following steps: acquiring the oil content and the porosity of a rock sample, and calculating the oil saturation of the rock sample according to the oil content and the porosity; calculating a first shale oil mobility evaluation parameter according to the oil content of the rock sample; calculating a second shale oil mobility evaluation parameter according to the oil saturation of the rock sample; evaluating the mobility of the shale oil based on the first shale oil mobility evaluation parameter and the second shale oil mobility evaluation parameter; wherein the oil content comprises a first oil content, a second oil content and a third oil content, the first oil content is obtained by the first rock sample based on a low-field nuclear magnetic resonance test, the second oil content is obtained by the second rock sample based on the low-field nuclear magnetic resonance test, and the third oil content is obtained by the second rock sample based on solvent extraction. According to the embodiment of the invention, the mobility evaluation result of the shale oil can more accord with objective conditions.

Description

Technical Field

[0001] The present invention relates to the technical field of petroleum exploitation and geological and mining exploration and development, and in particular to a method and device for evaluating the oil volume and mobility of shale oil. Background Art

[0002] Shale oil and gas and tight oil and gas have become important fossil energy sources. The oil content and mobility of tight rocks such as shale are important parameters for evaluating oil and gas resources, developing sweet spots and improving oil recovery. In the existing technology, solvent extraction methods such as dichloromethane are usually used to evaluate oil content, combined with step-by-step extraction to evaluate mobility.

[0003] However, the prior art has the following disadvantages:

[0004] (1) The rock samples need to be crushed and the solvent heated to evaporate. Light hydrocarbons are lost during the experiment, and the obtained oil content and oil saturation are low.

[0005] (2) The amount of movable oil obtained by step-by-step extraction tends to classify the adsorbed oil as movable oil, and is susceptible to the loss of light hydrocarbons by volatilization, resulting in a large deviation between the mobility evaluation results of shale oil and the actual situation. Summary of the invention

[0006] The purpose of the embodiment of the present invention is to provide a method and device for evaluating the oil content and mobility of shale oil, which can solve or partially solve the problems existing in the prior art. It should be noted that the method provided by the embodiment of the present invention is also applicable to the evaluation of the oil content and mobility of dense rocks such as mudstone, dense sandstone, carbonate rock, evaporite, etc., and is not limited here.

[0007] In order to achieve the above object, an embodiment of the present invention provides a method for evaluating the oil volume and mobility of shale oil, the method comprising:

[0008] Obtaining the oil content and porosity of a rock sample, and calculating the oil saturation of the rock sample based on the oil content and porosity; wherein the oil content includes a first oil content, a second oil content and a third oil content, the first oil content is obtained by testing the first rock sample based on low-field nuclear magnetic resonance, the second oil content is obtained by testing the second rock sample based on low-field nuclear magnetic resonance, the third oil content is obtained by solvent extraction of the second rock sample, the first rock sample is an original rock sample, and the second sample is a crushed rock sample;

[0009] Calculating a first shale oil mobility evaluation parameter according to the oil content of the rock sample;

[0010] Calculating a second shale oil mobility evaluation parameter according to the oil saturation of the rock sample;

[0011] Based on the first shale oil mobility evaluation parameter and the second shale oil mobility evaluation parameter, the mobility of the shale oil is evaluated.

[0012] Optionally, the porosity is obtained from a third rock sample based on low-field nuclear magnetic resonance testing, and the third rock sample is a saturated rock sample.

[0013] Optionally, the oil saturation includes a first oil saturation, a second oil saturation and a third oil saturation;

[0014] According to the oil content and porosity, the oil saturation of the rock sample is calculated using the following formula:

[0015] S o1 =w o1 ×ρ rock / (φ×ρ oil )×100%

[0016] In the formula, S o1 is the first oil saturation, w o1 is the first oil content, ρ rock is the rock density, φ is the porosity, ρ oil is the density of shale oil;

[0017] S o2 =w o2 ×ρ rock / (φ×ρ oil )×100%

[0018] In the formula, S o2 is the second oil saturation, w o2 is the second oil content, ρ rock is the rock density, φ is the porosity, ρ oil is the density of shale oil;

[0019] S o3 =w o3 ×ρ rock / (φ×ρ oil )×100%

[0020] In the formula, S o3 is the third oil saturation, w o3 is the third oil content, ρ rock is the rock density, φ is the porosity, ρ oil is the density of shale oil.

[0021] Optionally, the first shale oil mobility evaluation parameter is movable oil content and / or free oil content;

[0022] The second shale oil mobility evaluation parameter is movable oil saturation and / or free oil saturation.

[0023] Optionally, the first shale oil mobility parameter is movable oil content,

[0024] According to the oil content of the rock sample, the first shale oil mobility evaluation parameter is calculated, including:

[0025] The difference between the first oil content and the third oil content is used as the movable oil content.

[0026] Optionally, the first shale oil mobility parameter is free oil content,

[0027] According to the oil content of the rock sample, the first shale oil mobility evaluation parameter is calculated, including:

[0028] The difference between the first oil content and the second oil content is taken as the free oil content.

[0029] Optionally, the second shale oil mobility parameter is movable oil saturation,

[0030] According to the oil saturation of the rock sample, the second shale oil mobility evaluation parameter is calculated, including:

[0031] The difference between the first oil saturation and the third oil saturation is taken as the movable oil saturation.

[0032] Optionally, the second shale oil mobility parameter is free oil saturation,

[0033] According to the oil saturation of the rock sample, the second shale oil mobility evaluation parameter is calculated, including:

[0034] The difference between the first oil saturation and the second oil saturation is taken as the free oil saturation.

[0035] Optionally, the method further includes:

[0036] Substituting the first oil saturation into the following formula, the gas saturation is obtained:

[0037] S g =S o1 ×GOR / (1-GOR)×100%

[0038] In the formula, S g is the gas saturation, S o1 The first oil saturation, GOR, is the gas-oil ratio at underground conditions of the reservoir.

[0039] Optionally, the method further includes:

[0040] Substituting the first oil saturation and gas saturation into the following formula, the water saturation is obtained:

[0041] S w =100-S o1 -S g

[0042] In the formula, S w is water saturation, S o1 First oil saturation, S g is the gas saturation, and GOR is the gas-oil ratio of the underground conditions of the oil reservoir. Accordingly, an embodiment of the present invention also provides a shale oil oil volume and mobility evaluation device, the device comprising a calculation module and an evaluation module;

[0043] The calculation module is used to obtain the oil content and porosity of the rock sample, and calculate the oil saturation of the rock sample according to the oil content and porosity; wherein the oil content includes a first oil content, a second oil content and a third oil content, the first oil content is obtained by testing the first rock sample based on low-field nuclear magnetic resonance, the second oil content is obtained by testing the second rock sample based on low-field nuclear magnetic resonance, the third oil content is obtained by solvent extraction of the second rock sample, the first rock sample is an original rock sample, and the second sample is a crushed rock sample;

[0044] Calculating a first shale oil mobility evaluation parameter according to the oil content of the rock sample; and

[0045] According to the oil saturation of the rock sample, a second shale oil mobility evaluation parameter is calculated.

[0046] The evaluation module is used to evaluate the mobility of shale oil based on the first shale oil mobility evaluation parameter and the second shale oil mobility evaluation parameter.

[0047] Optionally, the oil saturation includes a first oil saturation, a second oil saturation and a third oil saturation;

[0048] According to the oil content and porosity, the oil saturation of the rock sample is calculated using the following formula:

[0049] S o1 =w o1 ×ρ rock / (φ×ρ oil )×100%

[0050] In the formula, S o1 is the first oil saturation, w o1 is the first oil content, ρ rock is the rock density, φ is the porosity, ρ oil is the density of shale oil;

[0051] S o2 =w o2 ×ρrock / (φ×ρ oil )×100%

[0052] In the formula, S o2 is the second oil saturation, w o2 is the second oil content, ρ rock is the rock density, φ is the porosity, ρ oil is the density of shale oil;

[0053] S o3 =w o3 ×ρ rock / (φ×ρ oil )×100%

[0054] In the formula, S o3 is the third oil saturation, w o3 is the third oil content, ρ rock is the rock density, φ is the porosity, ρ oil is the density of shale oil.

[0055] Optionally, the first shale oil mobility evaluation parameter is movable oil content and / or free oil content;

[0056] The second shale oil mobility evaluation parameter is movable oil saturation and / or free oil saturation.

[0057] Optionally, the calculation module is further used for:

[0058] Substituting the first oil saturation into the following formula, the gas saturation is obtained:

[0059] S g =S o1 ×GOR / (1-GOR)×100%

[0060] In the formula, S g is the gas saturation, S o1 The first oil saturation, GOR, is the gas-oil ratio at underground reservoir conditions.

[0061] Optionally, the calculation module is further used for:

[0062] Substituting the first oil saturation and gas saturation into the following formula, the water saturation is obtained:

[0063] S w =100-S o1 -S g

[0064] In the formula, S w is water saturation, S o1 First oil saturation, S gis the gas saturation, and GOR is the gas-oil ratio at underground reservoir conditions.

[0065] According to an embodiment of the present invention, the oil content and porosity of a rock sample are first obtained, and the oil saturation of the rock sample is calculated based on the oil content and the porosity. Then, a first shale oil mobility evaluation parameter is calculated based on the oil content of the rock sample, and a second shale oil mobility evaluation parameter is calculated based on the oil saturation of the rock sample. The first shale oil mobility evaluation parameter and the second shale oil mobility evaluation parameter are combined to evaluate the mobility of the shale oil, so that the shale oil mobility evaluation result is more accurate and more in line with the objective actual situation.

[0066] Other features and advantages of the embodiments of the present invention will be described in detail in the subsequent detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] The accompanying drawings are used to provide a further understanding of the embodiments of the present invention and constitute a part of the specification. Together with the following specific implementations, they are used to explain the embodiments of the present invention, but do not constitute a limitation on the embodiments of the present invention. In the accompanying drawings:

[0068] Figure 1 It is a flow chart of a method for evaluating the oil volume and mobility of shale oil provided by an embodiment of the present invention;

[0069] Figure 2 is a relationship diagram of the first oil content, the second oil content, the third oil content, the movable oil content and the free oil content provided by an embodiment of the present invention;

[0070] Figure 3 is a flow chart of a method for calculating a first oil content, a second oil content, a third oil content and porosity provided by an embodiment of the present invention;

[0071] Figure 4 is the first oil content (w o1 ) Distribution diagram (arranged from small to large);

[0072] Figure 5 It is a schematic diagram of oil, gas and water saturation of different rock samples provided by an embodiment of the present invention (arranged from shallow to deep in depth);

[0073] Figure 6 is the third oil content (absorbed oil content w of different rock samples provided in the embodiment of the present invention) o3 ) and the ratio of the third oil content to the first oil content w o3 / w o1 Schematic diagram of

[0074] Figure 7is the third oil saturation (adsorbed oil saturation S of different rock samples provided in the embodiment of the present invention. o3 ) and the third oil saturation accounts for the first oil saturation (S o1 )Comparison chart;

[0075] Figure 8 is the third oil content (absorbed oil content w o3 ) and TOC correlation diagram;

[0076] Fig. 9 is the third oil content (absorbed oil content w o3 ) and clay mineral content;

[0077] Fig.10 is the third oil content (absorbed oil content w o3 ) and movable oil content (w m1 ) Correlation diagram;

[0078] Fig.11 is the third oil content (absorbed oil content w o3 ) and movable oil ratio (w m1 / w o1 ) Correlation diagram;

[0079] Fig.12 is the first oil saturation (S o1 ) and movable oil saturation (S m1 ) Correlation diagram;

[0080] Fig.13 The clay mineral content and movable oil saturation (S m1 ) Correlation diagram;

[0081] Fig.14 The TOC content and movable oil saturation (S m1 ) Correlation diagram;

[0082] Fig.15 is the free oil content (w m2 ) and movable oil ratio (w m2 / w m1 ) Correlation diagram;

[0083] Fig.16 The TOC content and movable oil saturation (S m1 ) Correlation diagram;

[0084] Fig.17It is a comparison diagram of T2 relaxation time before saturation with water (first rock sample) and after saturation with water (third rock sample) provided by an embodiment of the present invention;

[0085] Fig.18 It is a comparison diagram of T2 relaxation time before saturation with water (first rock sample) and powder sample (second rock sample) provided in an embodiment of the present invention;

[0086] Fig.19 It is a structural block diagram of a shale oil mobility evaluation device provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0087] The specific implementation of the embodiment of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the embodiment of the present invention, and is not used to limit the embodiment of the present invention.

[0088] Figure 1 It is a flow chart of a method for evaluating the oil volume and mobility of shale oil provided in an embodiment of the present invention.

[0089] like Figure 1 As shown, the method for evaluating the oil volume and mobility of shale oil includes:

[0090] S110: Obtaining the oil content and porosity of the rock sample, and calculating the oil saturation of the rock sample according to the oil content and porosity;

[0091] The oil content includes a first oil content, a second oil content and a third oil content.

[0092] The first oil content is obtained by testing the first rock sample based on low-field nuclear magnetic resonance, and the first rock sample is an original rock sample.

[0093] For example, the original rock sample is subjected to a low-field nuclear magnetic resonance test to measure the T2 relaxation spectrum. Among them, T2 relaxation is positively correlated with pore size, short T2 relaxation corresponds to small pores, and long relaxation corresponds to large pores. The greater the intensity of the T2 spectrum, the greater the amount of oil content corresponding to the pore size. At the same time, the T2 spectrum intensity of the original rock sample is measured, and the oil content is calculated based on the oil mass and the marking line of the T2 spectrum intensity, and the first oil content is obtained by dividing the oil content by the rock sample mass.

[0094] The marking line is measured before or after the rock sample experiment. Oil from the same region as the rock sample or oil with the same properties can be used to prepare different masses, and then a nuclear magnetic resonance experiment is performed to obtain the T2 spectrum intensity, and then the marking line of oil mass and T2 spectrum intensity is fitted.

[0095] The second oil content is obtained by testing the second rock sample based on low-field nuclear magnetic resonance, and the second sample is a crushed rock sample.

[0096] For example, the original rock sample is crushed to a certain particle size for low-field nuclear magnetic resonance testing, and the T2 spectrum intensity of the crushed rock sample is measured. Among them, T2 relaxation is positively correlated with pore size, short T2 relaxation corresponds to small pores, and long relaxation corresponds to large pores. The greater the intensity of the T2 spectrum, the greater the oil content corresponding to the pore size. At the same time, the T2 spectrum intensity of the rock sample is measured, and the oil content is calculated based on the oil mass and the marking line of the T2 spectrum intensity. The oil content is divided by the mass of the rock sample to obtain the second oil content.

[0097] The marking line is measured before or after the rock sample experiment. Oil from the same region as the rock sample or oil with the same properties is used to prepare different masses, and then a nuclear magnetic resonance experiment is carried out to obtain the T2 spectrum intensity, and then the marking line of oil mass and T2 spectrum intensity is fitted.

[0098] The third oil content is obtained by solvent extraction of the second rock sample.

[0099] For example, the original rock sample is crushed to a certain particle size for solvent extraction (the solvent includes but is not limited to dichloromethane) to obtain the extracted oil content (the third oil content). Specifically, about 20g of rock powder (particle size <0.18mm) is placed in a filter cartridge and extracted for more than 12 hours using a Soxhlet extraction system with a dichloromethane solution. It should be noted that the embodiment of the present invention is not limited to this extraction method, and the extraction method of Dean Strak and others is also applicable and is not limited here.

[0100] The porosity is obtained by low-field nuclear magnetic resonance testing of the third rock sample, and the third rock sample is a saturated rock sample.

[0101] For example, a standard liquid (the liquid must be stable, not chemically reacting with the rock, volatile and metamorphic, and have a nuclear magnetic resonance response signal) is used as a liquid probe to inject into the rock, and the rock sample is pressurized and saturated. After the liquid probe fills the pores of the rock sample, the rock is taken out and put into the nuclear magnetic resonance instrument for analysis. A low-field nuclear magnetic resonance test is performed to measure the T2 spectrum of the rock sample. Among them, long relaxation corresponds to large pores, and the greater the intensity of the T2 spectrum, the greater the number of pores corresponding to the pore size. At the same time, the intensity of the T2 spectrum of the rock sample is measured, and the porosity of the rock sample is calculated based on the porosity and T2 spectrum intensity line.

[0102] The calibration line is measured before or after the rock sample experiment. The liquid probe used for the saturated rock sample is used to prepare different porosity standards, and then the nuclear magnetic resonance experiment is performed to obtain the T2 spectrum intensity. Then the calibration line of porosity and T2 spectrum intensity is fitted.

[0103] In some optional embodiments, the oil saturation of the rock sample is calculated according to the oil content and porosity using the following formula:

[0104] S o1 =w o1 ×ρ rock / (φ×ρ oil )×100%

[0105] In the formula, S o1 is the first oil saturation, w o1 is the first oil content, ρ rock is the rock density, φ is the porosity, ρ oil is the density of shale oil;

[0106] S o2 =w o2 ×ρ rock / (φ×ρ oil )×100%

[0107] In the formula, S o2 is the second oil saturation, w o2 is the second oil content, ρ rock is the rock density, φ is the porosity, ρ oil is the density of shale oil;

[0108] S o3 =w o3 ×ρ rock / (φ×ρ oil )×100%

[0109] In the formula, S o3 is the third oil saturation, w o3 is the third oil content, ρ rock is the rock density, φ is the porosity, ρ oil is the density of shale oil.

[0110] S120: Calculating a first shale oil mobility evaluation parameter according to the oil content of the rock sample;

[0111] The first shale oil mobility evaluation parameter may be movable oil content and / or free oil content;

[0112] Figure 2 A relationship diagram of the first oil content, the second oil content, the third oil content, the movable oil content and the free oil content provided in an embodiment of the present invention.

[0113] like Figure 2As shown, in some optional embodiments, the difference between the first oil content and the third oil content can be used as the movable oil content. The difference between the first oil content and the second oil content can be used as the free oil content.

[0114] S130: Calculating a second shale oil mobility evaluation parameter according to the oil saturation of the rock sample;

[0115] The second shale oil mobility evaluation parameter is movable oil saturation and / or free oil saturation.

[0116] In some optional embodiments, the difference between the first oil saturation and the third oil saturation may be used as the movable oil saturation.

[0117] In some optional embodiments, the difference between the first oil saturation and the second oil saturation may be used as the free oil saturation.

[0118] S140: Based on the first shale oil mobility evaluation parameter and the second shale oil mobility evaluation parameter, evaluate the mobility of shale oil.

[0119] Among them, the first shale oil mobility evaluation parameter and the second shale oil mobility evaluation parameter are positively correlated with the mobility of shale oil. The larger the values ​​of the first shale oil mobility evaluation parameter and the second shale oil mobility evaluation parameter, the stronger the mobility of shale oil. Specifically, the movable oil content, movable oil saturation, free oil content, free oil saturation and the mobility of shale oil are positively correlated. The larger the movable oil content, movable oil saturation, free oil content and free oil saturation, the stronger the mobility of shale oil.

[0120] According to an embodiment of the present invention, the oil content and porosity of a rock sample are first obtained, and the oil saturation of the rock sample is calculated based on the oil content and the porosity. Then, a first shale oil mobility evaluation parameter is calculated based on the oil content of the rock sample, and a second shale oil mobility evaluation parameter is calculated based on the oil saturation of the rock sample. The first shale oil mobility evaluation parameter and the second shale oil mobility evaluation parameter are combined to evaluate the mobility of the shale oil, so that the shale oil mobility evaluation result is more accurate and more in line with the objective actual situation.

[0121] In some optional implementations, the present invention also provides a method for calculating gas saturation and water saturation of rocks, comprising:

[0122] Substituting the first oil saturation into the following formula, the gas saturation is obtained:

[0123] S g =S o1 ×GOR / (1-GOR)×100%

[0124] In the formula, S g is the gas saturation, S o1 The first oil saturation, GOR, is the gas-oil ratio at underground reservoir conditions.

[0125] Substituting the first oil saturation and gas saturation into the following formula, the water saturation is obtained:

[0126] S w =100-S o1 -S g

[0127] In the formula, S w is water saturation, S o1 First oil saturation, S g is the gas saturation, and GOR is the gas-oil ratio at underground reservoir conditions.

[0128] The embodiments of the present invention have the following beneficial effects:

[0129] There is no need to crush the first rock sample or heat and volatilize it during the test process, which avoids the loss of light hydrocarbons during the experiment and makes the obtained oil content more reasonable;

[0130] It can obtain parameters such as oil saturation, water saturation, gas saturation, etc. with high accuracy;

[0131] The movable oil volume, free oil volume, movable oil saturation and free oil saturation that correspond well to the actual situation can be obtained;

[0132] The operation of the second rock sample can utilize the original solvent extraction method result data, saving resources;

[0133] There is no need to crush and extract the rock samples multiple times. The method is convenient and saves time.

[0134] The embodiments of the present invention are further described below with reference to specific examples.

[0135] Figure 3 It is a flow chart of a method for calculating a first oil content, a second oil content, a third oil content and porosity provided by an embodiment of the present invention.

[0136] First, the original rock sample was divided into three parts. The first rock sample was tested by low-field nuclear magnetic resonance using the Carr-Purcell-Meiboom-Gill (CPMG) sequence. Measure the T2 relaxation spectrum. T2 relaxation is positively correlated with pore size, short T2 relaxation corresponds to small pores, and long relaxation corresponds to large pores. The greater the intensity of the T2 spectrum, the greater the amount of oil content corresponding to the pore size. At the same time, the T2 spectrum intensity of the initial rock sample can be measured, and the oil content is calculated based on the oil mass and the marking line of the T2 spectrum intensity. The first oil content is obtained by dividing the oil content by the mass of the rock sample.

[0137] The calibration line is measured before or after the rock sample experiment. Oil from the same region as the rock sample or oil with the same properties is used to prepare different masses, and then the nuclear magnetic resonance experiment is carried out to obtain the T2 spectrum intensity. Then the calibration line of oil mass and T2 spectrum intensity is fitted.

[0138] Furthermore, the second rock sample is crushed to a certain particle size (preferably 60-80 mesh) and tested by low-field nuclear magnetic resonance using the Carr-Purcell-Meiboom-Gill (CPMG) sequence. The T2 spectrum intensity of the crushed rock sample is measured, and T2 relaxation is positively correlated with the pore size. Short T2 relaxation corresponds to small pores, and long relaxation corresponds to large pores. The greater the intensity of the T2 spectrum, the greater the amount of oil content corresponding to the pore size. At the same time, the T2 spectrum intensity of the rock sample can also be measured, and the oil content is calculated based on the oil mass and the marking line of the T2 spectrum intensity. The second oil content is obtained by dividing the oil content by the mass of the rock sample.

[0139] Further, the second rock sample was crushed to a certain particle size (60-80 mesh), and about 20g of rock powder (particle size <0.18mm) was placed in a filter cartridge and extracted by using a Soxhlet extraction system with a dichloromethane solution for more than 12 hours. The extraction steps are as follows: immerse the filter cartridge in a beaker filled with 200ml of dichloromethane, turn on the extraction circulation system, and reflux at a temperature of 85°C for more than 12 hours until the fluorescence of the extract drops below level 3; turn off the extraction circulation system, take out the filter cartridge, put the beaker into a fume hood, and concentrate the extract to 5-10mL at a temperature of 50°C; transfer the concentrated extract to a weighing bottle, and then weigh the mass of the extract after the solvent is completely evaporated at room temperature. Dichloromethane extract (w o3 ) is defined as the adsorbed oil content, i.e. the third oil content. Usually adsorbed on the surface of organic matter and clay minerals, the extraction process lasts for several weeks on crushed samples.

[0140] Furthermore, sample 3 was pressurized (30 MPa) and saturated with standard oil for 24 hours (the third rock sample can be the first rock sample after the experiment). After the standard white oil filled the pores of the rock sample, it was taken out and put into the nuclear magnetic resonance instrument for analysis. Low-field nuclear magnetic resonance test using Carr-Purcell-Meiboom-Gill (CPMG) sequence Measure the T2 spectrum of rock samples. Long relaxation corresponds to large pores. The greater the intensity of the T2 spectrum, the greater the number of pores corresponding to that pore size. At the same time, the intensity of the T2 spectrum of rock samples can also be measured, and the porosity (φ) of the rock sample can be calculated based on the porosity and T2 spectrum intensity line.

[0141] The calibration line is measured before or after the rock sample experiment. The fluid used to saturate the rock sample is used to prepare different porosity standards, and then the nuclear magnetic resonance experiment is performed to obtain the T2 spectrum intensity. Then the calibration line of porosity and T2 spectrum intensity is fitted.

[0142] Furthermore, based on formulas (1), (2), (3), (4) and (5), the first oil saturation, the second oil saturation, the third oil saturation, the gas saturation and the water saturation are calculated, and then the difference between the first oil content and the third oil content is taken as the movable oil content, the difference between the first oil content and the second oil content is taken as the free oil content, the difference between the first oil saturation and the third oil saturation is taken as the movable oil saturation, and the difference between the first oil saturation and the second oil saturation is taken as the free oil saturation.

[0143] Table 1 shows the meaning of various oil contents and saturation.

[0144]

[0145]

[0146] Furthermore, the obtained oil content and oil saturation were analyzed.

[0147] In this specific example, the total oil content is 7.2-13.4 mg / g.rock, with an average of 10.7 mg / g.rock ( Figure 4 The oil saturation in the pores is 23-40%, with an average of 32%. The GOR of the underground conditions of the reservoir is 0.4m 3 / m 3 Gas saturation is 15.8-26.9%, with an average of 21%, and water saturation is 32.8-60.6%, with an average of 47% ( Figure 5 ).

[0148] Furthermore, the obtained third oil content (adsorbed oil content) and the third oil saturation are analyzed.

[0149] The adsorbed oil content is 1.3-9 mg / g.rock, with an average of 5.3 mg / g.rock. It accounts for 18-67% of the total oil content, with an average of 48% ( Figure 6). Since the extraction experiment requires the sample to be crushed and heated, hydrocarbons will volatilize, while the NMR experiment does not require sample crushing and heating, and the time is short, which can avoid the volatilization of light hydrocarbons and collect more oil signals. o3 The content increased from 1.3mg / g.rock to 9.0mg / g.rock, w o3 / w o1 The coefficient gradually increases from 18% to 68%, with an average of about 50% ( Figure 6 The volume saturation of adsorbed oil accounts for 8.4-16.2% of the total pores, with an average of 15.4% ( Figure 7 ).

[0150] Third, the oil content is affected by the adsorption of organic matter and clay minerals. o3 As TOC and clay mineral content increase, they both show an upward trend ( Figure 8 , Fig. 9 ). Therefore, w o3 However, shale oil in layers with high organic matter and clay mineral contents is mainly stored in an adsorbed state and is not easy to mobilize. o3 ) is highly judged to be a good shale oil development layer.

[0151] Furthermore, the obtained movable oil content and movable oil saturation are analyzed.

[0152] Movable oil content (w m1 ) is 3-7 mg / g.rock, with an average of 5.4 mg / g.rock. o3 The content increases and the movable oil content decreases ( Fig.10 ), indicating that mobility is affected by adsorption. The higher the adsorbed oil content, the lower the movable oil content, and the two increase while the other decreases. m1 / w o1 )With w o3 The content increased and decreased ( Fig.11 ).

[0153] In terms of saturation, the movable oil saturation S m1 The range is 10-32%, with an average of 17% ( Fig.12 The increase of total oil saturation indicates that the higher the pore filling degree is, the greater the movable volume is. The increase of TOC content and clay mineral content in shale reservoir indicates that the movable oil saturation S m1 reduce( Fig.13 , Fig.14), indicating that organic matter and clay minerals have strong adsorption to shale oil, which hinders the movable oil. However, since low TOC content will reduce the amount of crude oil generated and the total oil content, TOC cannot be too low. Therefore, the medium-high TOC content and low clay mineral content layer are the most favorable movable oil layers.

[0154] Furthermore, the obtained free oil content and free oil saturation were analyzed.

[0155] Free oil content (w m2 ) is 2.48%-4.52mg / g rock. Free oil ratio (w m2 / w o1 ) is 24% to 36%, with an average of 29% ( Fig.15 ). Free oil saturation (S m2 ) is 7-10%, with an average of 9%. Considering that the recovery rate of shale oil producing areas today is less than 10%, the free oil volume is closest to the oil produced in the oil field. The average oil saturation of the pores is 32%, and the movable oil saturation is 17%. The movable oil accounts for about half of the total oil, and the free oil accounts for a quarter ( Fig.16 ).

[0156] Furthermore, the mobility of shale oil in different pore sizes was analyzed.

[0157] Since the T2 spectrum is proportional to the pore diameter, the law of T2 from small to large also reflects the law of pore size change. The shale reservoir pores are bimodal, with a distribution range of 0.01-10ms and 10ms-200ms. The oil occurrence is also bimodal, with the main occurrence pore size being the smaller pore size range of 0.01-1ms. The larger pores with a long relaxation of about 10ms account for a smaller proportion. Since the small pores are filled with oil, it is speculated that gas and water exist in larger pores greater than 0.2ms ( Fig.17 ).

[0158] The oil in the small pores can also move, and the oil in the range of 0.01-1ms can be lost after the sample is crushed ( Fig.18 ), most samples indicate that volatile light hydrocarbons are evenly distributed in the pores, and not only the oil in the long T2 pores can be produced. The traditional method uses the T2 cutoff value to distinguish movable oil, and believes that the long relaxation larger pores greater than the T2 cutoff value represent movable oil. This method is unreasonable and easily ignores the contribution of short relaxation or small pores to oil production. Shale oil is mostly produced by horizontal well pressure depletion, connecting fractures, large pores and some small pores, and releasing pressure during the production process, causing oil expansion. Since large pores and small pores are interconnected, the oil in both can be discharged.

[0159] Accordingly, Fig.19 It is a structural block diagram of a shale oil mobility evaluation device provided in an embodiment of the present invention.

[0160] like Fig.19 As shown, the device includes a calculation module and an evaluation module;

[0161] The calculation module is used to obtain the oil content and porosity of the rock sample, and calculate the oil saturation of the rock sample according to the oil content and porosity; wherein the oil content includes a first oil content, a second oil content and a third oil content, the first oil content is obtained by testing the first rock sample based on low-field nuclear magnetic resonance, the second oil content is obtained by testing the second rock sample based on low-field nuclear magnetic resonance, the third oil content is obtained by solvent extraction of the second rock sample, the first rock sample is an original rock sample, and the second sample is a crushed rock sample;

[0162] Calculating a first shale oil mobility evaluation parameter according to the oil content of the rock sample; and

[0163] According to the oil saturation of the rock sample, a second shale oil mobility evaluation parameter is calculated.

[0164] The evaluation module is used to evaluate the mobility of shale oil based on the first shale oil mobility evaluation parameter and the second shale oil mobility evaluation parameter.

[0165] The oil saturation includes a first oil saturation, a second oil saturation and a third oil saturation;

[0166] According to the oil content and porosity, the oil saturation of the rock sample is calculated using the following formula:

[0167] S o1 =w o1 ×ρ rock / (φ×ρ oil )×100%

[0168] In the formula, S o1 is the first oil saturation, w o1 is the first oil content, ρ rock is the rock density, φ is the porosity, ρ oil is the density of shale oil;

[0169] S o2 =w o2 ×ρ rock / (φ×ρ oil )×100%

[0170] In the formula, S o2 is the second oil saturation, w o2 is the second oil content, ρ rock is the rock density, φ is the porosity, ρ oil is the density of shale oil;

[0171] S o3 =w o3 ×ρ rock / (φ×ρ oil )×100%

[0172] In the formula, S o3 is the third oil saturation, w o3 is the third oil content, ρ rock is the rock density, φ is the porosity, ρ oil is the density of shale oil.

[0173] The first shale oil mobility evaluation parameter is movable oil content and / or free oil content;

[0174] The second shale oil mobility evaluation parameter is movable oil saturation and / or free oil saturation.

[0175] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application may adopt the form of a computer program product implemented in one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that include computer-usable program code.

[0176] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0177] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0178] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0179] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0180] The memory may include non-permanent memory in a computer-readable medium, random access memory (RAM) and / or non-volatile memory in the form of read-only memory (ROM) or flash RAM. The memory is an example of a computer-readable medium.

[0181] Computer readable media include permanent and non-permanent, removable and non-removable media that can be implemented by any method or technology to store information. Information can be computer readable instructions, data structures, program modules or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, compact disk read-only memory (CD-ROM), digital versatile disk (DVD) or other optical storage, magnetic cassettes, magnetic tape magnetic disk storage or other magnetic storage devices or any other non-transmission media that can be used to store information that can be accessed by a computing device. As defined herein, computer readable media does not include temporary computer readable media (transitory media), such as modulated data signals and carrier waves.

[0182] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0183] The above are only embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included within the scope of the claims of the present application.

Claims

1. A method for evaluating the oil volume and mobility of shale oil, characterized in that: The method includes: Obtaining the oil content and porosity of the rock sample, and calculating the oil saturation of the rock sample based on the oil content and porosity; Calculating a first shale oil mobility evaluation parameter according to the oil content of the rock sample; Calculating a second shale oil mobility evaluation parameter according to the oil saturation of the rock sample; Based on the first shale oil mobility evaluation parameter and the second shale oil mobility evaluation parameter, evaluating the mobility of shale oil; The oil content includes a first oil content, a second oil content and a third oil content, wherein the first oil content is obtained based on a low-field nuclear magnetic resonance test of the first rock sample, the second oil content is obtained based on a low-field nuclear magnetic resonance test of the second rock sample, and the third oil content is obtained based on solvent extraction of the second rock sample, the first rock sample is an original rock sample, and the second sample is a crushed rock sample.

2. The method for evaluating the oil volume and mobility of shale oil according to claim 1, characterized in that: The porosity is obtained by low-field nuclear magnetic resonance testing of the third rock sample, and the third rock sample is a saturated rock sample.

3. The method for evaluating the oil volume and mobility of shale oil according to claim 1 or 2, characterized in that: The oil saturation includes a first oil saturation, a second oil saturation and a third oil saturation; According to the oil content and porosity, the oil saturation of the rock sample is calculated using the following formula: S o1 =w o1 ×ρ rock / (φ×ρ oil )×100% In the formula, S o1 is the first oil saturation, w o1 is the first oil content, ρ rock is the rock density, φ is the porosity, ρ oil is the density of shale oil; S o2 =w o2 ×ρ rock / (φ×ρ oil )×100% In the formula, S o2 is the second oil saturation, w o2 is the second oil content, ρ rock is the rock density, φ is the porosity, ρ oil is the density of shale oil; S o3 =w o3 ×ρ rock / (φ×ρ oil )×100% In the formula, S o3 is the third oil saturation, w o3 is the third oil content, ρ rock is the rock density, φ is the porosity, ρ oil is the density of shale oil.

4. The method for evaluating the amount and mobility of shale oil according to claim 3, characterized in that: The first shale oil mobility evaluation parameter is movable oil content and / or free oil content; The second shale oil mobility evaluation parameter is movable oil saturation and / or free oil saturation.

5. The method for evaluating the oil volume and mobility of shale oil according to claim 4, characterized in that: The first shale oil mobility parameter is the movable oil content, According to the oil content of the rock sample, the first shale oil mobility evaluation parameter is calculated, including: The difference between the first oil content and the third oil content is used as the movable oil content.

6. The method for evaluating the amount and mobility of shale oil according to claim 4, characterized in that: The first shale oil mobility parameter is free oil content, According to the oil content of the rock sample, the first shale oil mobility evaluation parameter is calculated, including: The difference between the first oil content and the second oil content is taken as the free oil content.

7. The method for evaluating the amount and mobility of shale oil according to claim 4, characterized in that: The second shale oil mobility parameter is the movable oil saturation. According to the oil saturation of the rock sample, the second shale oil mobility evaluation parameter is calculated, including: The difference between the first oil saturation and the third oil saturation is taken as the movable oil saturation.

8. The method for evaluating the amount and mobility of shale oil according to claim 4, characterized in that: The second shale oil mobility parameter is free oil saturation, According to the oil saturation of the rock sample, the second shale oil mobility evaluation parameter is calculated, including: The difference between the first oil saturation and the second oil saturation is taken as the free oil saturation.

9. The method for evaluating the oil volume and mobility of shale oil according to claim 3, characterized in that: The method further comprises: Substituting the first oil saturation into the following formula, the gas saturation is obtained: S g =S o1 ×GOR / (1-GOR)×100% In the formula, S g is the gas saturation, S o1 The first oil saturation, GOR, is the gas-oil ratio at underground reservoir conditions.

10. The method for evaluating the oil volume and mobility of shale oil according to claim 9, characterized in that: The method further comprises: Substituting the first oil saturation and gas saturation into the following formula, the water saturation is obtained: S w =100-S o1 -S g In the formula, S w is water saturation, S o1 First oil saturation, S g is the gas saturation, and GOR is the gas-oil ratio at underground reservoir conditions.

11. A shale oil quantity and mobility evaluation device, characterized in that: The device includes a calculation module and an evaluation module; The calculation module is used to obtain the oil content and porosity of the rock sample, and calculate the oil saturation of the rock sample based on the oil content and porosity; Calculating a first shale oil mobility evaluation parameter according to the oil content of the rock sample; and calculating a second shale oil mobility evaluation parameter according to the oil saturation of the rock sample; The oil content includes a first oil content, a second oil content and a third oil content, wherein the first oil content is obtained by testing the first rock sample based on low-field nuclear magnetic resonance, the second oil content is obtained by testing the second rock sample based on low-field nuclear magnetic resonance, and the third oil content is obtained by solvent extraction of the second rock sample, the first rock sample is an original rock sample, and the second sample is a crushed rock sample; The evaluation module is used to evaluate the mobility of shale oil based on the first shale oil mobility evaluation parameter and the second shale oil mobility evaluation parameter.

12. The shale oil quantity and mobility evaluation device according to claim 11, characterized in that: The oil saturation includes a first oil saturation, a second oil saturation and a third oil saturation; According to the oil content and porosity, the oil saturation of the rock sample is calculated using the following formula: S o1 =w o1 ×ρ rock / (φ×ρ oil )×100% In the formula, S o1 is the first oil saturation, w o1 is the first oil content, ρ rock is the rock density, φ is the porosity, ρ oil is the density of shale oil; S o2 =w o2 ×ρ rock / (φ×ρ oil )×100% In the formula, S o2 is the second oil saturation, w o2 is the second oil content, ρ rock is the rock density, φ is the porosity, ρ oil is the density of shale oil; S o3 =w o3 ×ρ rock / (φ×ρ oil )×100% In the formula, S o3 is the third oil saturation, w o3 is the third oil content, ρ rock is the rock density, φ is the porosity, ρ oil is the density of shale oil.

13. The shale oil quantity and mobility evaluation device according to claim 11, characterized in that: The first shale oil mobility evaluation parameter is movable oil content and / or free oil content; The second shale oil mobility evaluation parameter is movable oil saturation and / or free oil saturation.

14. The shale oil quantity and mobility evaluation device according to claim 12, characterized in that: The calculation module is also used for: Substituting the first oil saturation into the following formula, the gas saturation is obtained: S g =S o1 ×GOR / (1-GOR)×100% In the formula, S g is the gas saturation, S o1 The first oil saturation, GOR, is the gas-oil ratio at underground reservoir conditions.

15. The shale oil quantity and mobility evaluation device according to claim 14, characterized in that: The calculation module is also used for: Substituting the first oil saturation and gas saturation into the following formula, the water saturation is obtained: S w =100-S o1 -S g In the formula, S w is water saturation, S o1 First oil saturation, S g is the gas saturation, and GOR is the gas-oil ratio at underground reservoir conditions.

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