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

Abstract

This invention provides a method and apparatus for evaluating the oil content and mobility of shale oil, belonging to the field of petroleum extraction and geological and mining exploration and development technology. The method includes: 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; calculating a first shale oil mobility evaluation parameter based on the oil content of the rock sample; calculating a second shale oil mobility evaluation parameter based on the oil saturation of the rock sample; and evaluating the mobility of the shale oil based on the first and second shale oil mobility evaluation parameters. The oil content includes a first oil content, a second oil content, and a third oil content. The first oil content is obtained from a first rock sample based on low-field nuclear magnetic resonance (NMR) testing, the second oil content is obtained from a second rock sample based on low-field NMR testing, and the third oil content is obtained from a second rock sample based on solvent extraction. This invention allows the shale oil mobility evaluation results to better reflect objective conditions.

Description

Technical Field

[0001] This invention relates to the field of petroleum extraction and geological and mining exploration and development technology, specifically to a method and apparatus for evaluating the quantity and mobility of shale oil. Background Technology

[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 recovery rates. Current technologies typically use solvent extraction methods such as dichloromethane to evaluate oil content, combined with stepwise extraction to evaluate mobility.

[0003] However, existing technologies have the following drawbacks:

[0004] (1) The rock sample needs to be crushed and the solvent needs to be heated and evaporated. Light hydrocarbons are lost during the experiment, resulting in low oil content and oil saturation.

[0005] (2) The amount of movable oil obtained by stepwise extraction is easy to classify adsorbed oil as movable oil, and it is easily lost due to the volatilization of light hydrocarbons, resulting in a large deviation between the evaluation results of the mobility of shale oil and the actual situation. Summary of the Invention

[0006] The purpose of this invention is to provide a method and apparatus for evaluating the oil content and mobility of shale oil. This invention can solve or partially solve the problems existing in the prior art. It should be noted that the method provided in this invention is also applicable to evaluating the oil content and mobility of tight rocks such as mudstone, tight sandstone, carbonate rocks, and evaporites; therefore, it is not limited thereto.

[0007] To achieve the above objectives, embodiments of the present invention provide a method for evaluating the quantity and mobility of shale oil, the method comprising:

[0008] The oil content and porosity of a rock sample are obtained, and the oil saturation of the rock sample is calculated 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 from a first rock sample based on low-field nuclear magnetic resonance testing, the second oil content is obtained from a second rock sample based on low-field nuclear magnetic resonance testing, and the third oil content is obtained from a second rock sample based on solvent extraction; the first rock sample is a raw rock sample, and the second sample is a crushed rock sample.

[0009] Based on the oil content of the rock sample, calculate the mobility evaluation parameters for the first shale oil.

[0010] Based on the oil saturation of the rock sample, calculate the mobility evaluation parameters for the second shale oil.

[0011] The mobility of shale oil is evaluated based on the first and second shale oil mobility evaluation parameters.

[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] Based on 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 For the first oil saturation, w o1 The first oil content, ρ rock ρ is the rock density, φ is the porosity, and ρ is the density of the rock. oil The density of shale oil;

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

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

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

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

[0021] Optionally, the first shale oil mobility evaluation parameters are mobile oil content and / or free oil content;

[0022] The second shale oil mobility evaluation parameters are mobile oil saturation and / or free oil saturation.

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

[0024] Based on the oil content of the rock sample, the mobility evaluation parameters for the first shale oil were calculated, including:

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

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

[0027] Based on the oil content of the rock sample, the mobility evaluation parameters for the first shale oil were 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 the mobile oil saturation.

[0030] Based on the oil saturation of the rock samples, the mobility evaluation parameters for the second shale oil were 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 the free oil saturation.

[0033] Based on the oil saturation of the rock samples, the mobility evaluation parameters for the second shale oil were 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, we obtain the gas saturation:

[0037] S g =S o1 ×GOR / (1-GOR)×100%

[0038] In the formula, S g S represents the gas saturation level. o1 First oil saturation, GOR is the gas-oil ratio of the reservoir's subsurface conditions.

[0039] Optionally, the method further includes:

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

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

[0042] In the formula, S w S represents the water saturation level. o1 First oil saturation, S g GOR represents the gas saturation level and the gas-oil ratio under subsurface conditions of the reservoir. Accordingly, this invention also provides a device for evaluating the oil quantity and mobility of shale oil, 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 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 low-field nuclear magnetic resonance testing of a first rock sample, the second oil content is obtained by low-field nuclear magnetic resonance testing of a second rock sample, and the third oil content is obtained by solvent extraction of a second rock sample, the first rock sample is an original rock sample, and the second sample is a crushed rock sample;

[0044] Based on the oil content of the rock samples, calculate the mobility evaluation parameters for the first shale oil; and

[0045] Based on the oil saturation of the rock sample, the mobility evaluation parameters for the second shale oil were 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] Based on 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 For the first oil saturation, w o1 The first oil content, ρ rock ρ is the rock density, φ is the porosity, and ρ is the density of the rock. oil The density of shale oil;

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

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

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

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

[0055] Optionally, the first shale oil mobility evaluation parameters are mobile oil content and / or free oil content;

[0056] The second shale oil mobility evaluation parameters are mobile oil saturation and / or free oil saturation.

[0057] Optionally, the computing module is further configured to:

[0058] Substituting the first oil saturation into the following formula, we obtain the gas saturation:

[0059] S g =S o1 ×GOR / (1-GOR)×100%

[0060] In the formula, S g S represents the gas saturation level. o1 First oil saturation, GOR is the gas-oil ratio of the reservoir's subsurface conditions.

[0061] Optionally, the computing module is further configured to:

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

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

[0064] In the formula, S w S represents the water saturation level. o1 First oil saturation, S gGOR represents the gas saturation level, and GOR represents the gas-oil ratio under the subsurface conditions of the reservoir.

[0065] In this embodiment of the 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 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. By combining the first and second shale oil mobility evaluation parameters, the mobility of shale oil is evaluated, making the shale oil mobility evaluation results more accurate and more consistent with the objective reality.

[0066] Other features and advantages of the embodiments of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0067] The accompanying drawings are provided to further illustrate embodiments of the present invention and form part of the specification. They are used together with the following detailed description to explain the embodiments of the present invention, but do not constitute a limitation thereof. In the drawings:

[0068] Figure 1 This is a flowchart of a method for evaluating the quantity and mobility of shale oil provided in an embodiment of the present invention;

[0069] Figure 2 This is a graph showing the relationship between the first oil content, the second oil content, the third oil content, the mobile oil content, and the free oil content, provided in an embodiment of the present invention.

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

[0071] Figure 4 The first oil content (w) of different rock samples provided in the embodiments of the present invention is... o1 Distribution diagram (arranged from smallest to largest);

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

[0073] Figure 6 This refers to the third oil content (adsorbed oil content w) of different rock samples provided in the embodiments of the present invention. o3 The ratio of the third oil content to the first oil content (w) o3 / w o1 A schematic diagram;

[0074] Figure 7This refers to the third oil saturation (adsorbed oil saturation S) of different rock samples provided in the embodiments of the present invention. o3 The third oil saturation level accounts for the first oil saturation level (S) o1 Comparison chart;

[0075] Figure 8 The third oil content (adsorbed oil content w) provided in the embodiments of the present invention o3 A diagram illustrating the correlation between ( ) and TOC;

[0076] Figure 9 The third oil content (adsorbed oil content w) provided in the embodiments of the present invention o3 Schematic diagram showing the correlation between clay mineral content and clay mineral content;

[0077] Figure 10 The third oil content (adsorbed oil content w) provided in the embodiments of the present invention o3 ) and movable oil content (w m1 Correlation diagram;

[0078] Figure 11 The third oil content (adsorbed oil content w) provided in the embodiments of the present invention o3 ) and movable oil ratio (w m1 / w o1 Correlation diagram;

[0079] Figure 12 The first oil saturation (S) provided in the embodiments of the present invention o1 ) and movable oil saturation (S) m1 Correlation diagram;

[0080] Figure 13 The clay mineral content and movable oil saturation (S) provided in the embodiments of the present invention are... m1 Correlation diagram;

[0081] Figure 14 The TOC content and mobile oil saturation (S) provided in the embodiments of the present invention are... m1 Correlation diagram;

[0082] Figure 15 The free oil content (w) provided in the embodiments of the present invention is m2 ) and movable oil ratio (w m2 / w m1 Correlation diagram;

[0083] Figure 16 The TOC content and mobile oil saturation (S) provided in the embodiments of the present invention are... m1 Correlation diagram;

[0084] Figure 17This is a comparison chart of T2 relaxation times before (first rock sample) and after (third rock sample) saturation with water, provided in an embodiment of the present invention.

[0085] Figure 18 This is a comparison chart of the T2 relaxation times of the first rock sample before saturation with water and the powder sample (second rock sample) provided in an embodiment of the present invention.

[0086] Figure 19 This is a structural block diagram of a shale oil mobility evaluation device provided in an embodiment of the present invention. Detailed Implementation

[0087] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the scope of the present invention.

[0088] Figure 1 This is a flowchart of a method for evaluating the quantity and mobility of shale oil provided in an embodiment of the present invention.

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

[0090] S110: 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;

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

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

[0093] For example, low-field nuclear magnetic resonance (NMR) testing is performed on the original rock sample to 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. A higher T2 spectrum intensity corresponds to a greater amount of oil at that pore size. Simultaneously, the T2 spectrum intensity of the original rock sample is measured, and the oil content is calculated based on the correlation between oil mass and T2 spectrum intensity. Dividing the oil content by the rock sample mass yields the first oil content.

[0094] The calibration line is measured before or after the rock sample experiment. It can be prepared with oil from the same region as the rock sample or with the same properties, in different masses, and then nuclear magnetic resonance experiments are performed to obtain the T2 spectrum intensity. The calibration line is then fitted to the oil mass and the T2 spectrum intensity.

[0095] The second oil content was obtained from a second rock sample based on low-field nuclear magnetic resonance testing. The second sample was a crushed rock sample.

[0096] For example, raw rock samples are crushed to a certain particle size and subjected to low-field nuclear magnetic resonance (NMR) testing to measure the T2 spectral intensity of the crushed rock samples. T2 relaxation is positively correlated with pore size; short T2 relaxation corresponds to small pores, and long relaxation corresponds to large pores. A higher T2 spectral intensity corresponds to a greater amount of oil at that pore size. Simultaneously, by measuring the T2 spectral intensity of the rock samples, the oil content is calculated based on the correlation between oil mass and T2 spectral intensity. Dividing the oil content by the rock sample mass yields a second oil content.

[0097] The calibration line is measured before or after the rock sample experiment. Different masses of oil from the same region as the rock sample or with the same properties are prepared, and then nuclear magnetic resonance experiments are performed to obtain the T2 spectrum intensity. The calibration line is then fitted to the oil mass and the T2 spectrum intensity.

[0098] The third oil content was obtained from the second rock sample based on solvent extraction.

[0099] For example, the original rock sample is pulverized to a certain particle size and then subjected to solvent extraction (solvents include, but are not limited to, dichloromethane) to obtain the extracted oil content (third oil content). Specifically, approximately 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 dichloromethane solution. It should be noted that the embodiments of the present invention are not limited to this extraction method; extraction methods such as those used by Dean Strak are also applicable and are not limited here.

[0100] The porosity was obtained from a third rock sample based on low-field nuclear magnetic resonance testing, and the third rock sample was a saturated rock sample.

[0101] For example, a standard liquid (which must be stable, not chemically reactive with the rock, volatile and prone to deterioration, and possess a nuclear magnetic resonance (NMR) response signal) is injected into the rock as a liquid probe. The rock sample is pressurized and saturated, and after the liquid probe fills the pores of the rock sample, the rock is removed and placed in an NMR spectrometer for analysis. Low-field NMR testing is performed, and the T2 spectrum of the rock sample is measured. Longer relaxation times correspond to larger pores; the greater the intensity of the T2 spectrum, the more pores of that size there are. Simultaneously, the intensity of the T2 spectrum of the rock sample is measured, and the porosity of the rock sample is calculated based on the calibration curve between porosity and T2 spectrum intensity.

[0102] The calibration curve is measured before or after the rock sample experiment. Using the same liquid probe as that used for saturated rock samples, standard samples with different porosities are prepared, and then nuclear magnetic resonance (NMR) experiments are performed to obtain the T2 spectral intensity. The calibration curve is then obtained by fitting the porosity to the T2 spectral intensity.

[0103] In some alternative embodiments, the oil saturation of the rock sample is calculated using the following formula based on the oil content and porosity:

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

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

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

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

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

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

[0110] S120: Calculate the mobility evaluation parameters of the first shale oil based on the oil content of the rock sample;

[0111] The first shale oil mobility evaluation parameter can be the mobile oil content and / or free oil content;

[0112] Figure 2 The diagram shows the relationship between the first oil content, the second oil content, the third oil content, the mobile oil content, and the free oil content, provided for embodiments 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: Calculate the second shale oil mobility evaluation parameters based on the oil saturation of the rock sample;

[0115] The second shale oil mobility evaluation parameters are mobile oil saturation and / or free oil saturation.

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

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

[0118] S140: Evaluate the mobility of shale oil based on the first shale oil mobility evaluation parameter and the second shale oil mobility evaluation parameter.

[0119] Among them, the first and second shale oil mobility evaluation parameters are positively correlated with the mobility of shale oil; the higher the values ​​of the first and second shale oil mobility evaluation parameters, the stronger the mobility of the shale oil. Specifically, the mobile oil content, mobile oil saturation, free oil content, and free oil saturation are positively correlated with the mobility of shale oil; the higher the mobile oil content, mobile oil saturation, free oil content, and free oil saturation, the stronger the mobility of the shale oil.

[0120] In this embodiment of the 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 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. By combining the first and second shale oil mobility evaluation parameters, the mobility of shale oil is evaluated, making the shale oil mobility evaluation results more accurate and more consistent with the objective reality.

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

[0122] Substituting the first oil saturation into the following formula, we obtain the gas saturation:

[0123] S g =S o1 ×GOR / (1-GOR)×100%

[0124] In the formula, S g S represents the gas saturation level. o1 First oil saturation, GOR is the gas-oil ratio of the reservoir's subsurface conditions.

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

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

[0127] In the formula, S w S represents the water saturation level. o1 First oil saturation, S g GOR represents the gas saturation level, and GOR represents the gas-oil ratio under the subsurface conditions of the reservoir.

[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 volatilize it during the testing process. The loss of light hydrocarbons is avoided during the experiment, and the oil content obtained is more reasonable.

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

[0131] It can obtain movable oil quantity, free oil quantity, movable oil saturation, and free oil saturation that correspond well to the actual situation;

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

[0133] The method is convenient and time-saving, eliminating the need for multiple crushing and extraction of rock samples.

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

[0135] Figure 3 This is a flowchart of a method for calculating the first oil content, the second oil content, the third oil content, and porosity provided in an embodiment of the present invention.

[0136] First, the original rock sample was divided into three parts. The first rock sample was subjected to low-field nuclear magnetic resonance (NMR) testing using the Carr-Purcell-Meiboom-Gill (CPMG) sequence. The T2 relaxation spectrum is measured. T2 relaxation is positively correlated with pore size; short T2 relaxation corresponds to small pores, and long relaxation corresponds to large pores. A higher T2 spectrum intensity corresponds to a greater amount of oil at that pore size. Simultaneously, the T2 spectrum intensity of the initial rock sample can be measured. Based on the oil mass and the T2 spectrum intensity calibration, the oil content is calculated, and the oil content is divided by the rock sample mass to obtain the initial oil content.

[0137] The calibration curve is measured before or after the rock sample experiment. Different masses of oil from the same region as the rock sample or with similar properties are prepared, and then nuclear magnetic resonance (NMR) experiments are performed to obtain the T2 spectral intensity. The calibration curve is then obtained by fitting the oil mass to the T2 spectral intensity.

[0138] Furthermore, the second rock sample was pulverized to a certain particle size (preferably 60-80 mesh) and subjected to low-field nuclear magnetic resonance testing using a Carr-Purcell-Meiboom-Gill (CPMG) sequence. The intensity of the T2 spectrum in crushed rock samples was measured, and T2 relaxation was positively correlated with pore size. Short T2 relaxation corresponds to small pores, while long relaxation corresponds to large pores. The greater the intensity of the T2 spectrum, the greater the amount of oil content corresponding to that pore size. Simultaneously, the T2 spectrum intensity of the rock samples could be measured, and the oil content could be calculated based on the calibration curve of oil mass and T2 spectrum intensity. Dividing the oil content by the rock sample mass yielded a second oil content.

[0139] Further, the second rock sample was pulverized to a certain particle size (60-80 mesh). Approximately 20g of rock powder (particle size <0.18mm) was placed in a filter cartridge and extracted for over 12 hours using a Soxhlet extraction system with dichloromethane solution. The extraction steps were as follows: the filter cartridge was immersed in a beaker containing 200ml of dichloromethane, the extraction circulation system was turned on, and reflux was carried out at 85°C for more than 12 hours until the fluorescence of the extract dropped below level 3; the extraction circulation system was turned off, the filter cartridge was removed, and the beaker was placed in a fume hood to concentrate the extract to 5-10mL at 50°C; the concentrated extract was transferred to a weighing bottle, and the mass of the extract was weighed after the solvent had completely evaporated at room temperature. Dichloromethane extract (w o3 This is defined as the adsorbed oil content, also known as the third oil content. It is typically adsorbed onto the surface of organic matter and clay minerals, and the extraction process on a pulverized sample can last for several weeks.

[0140] Furthermore, sample 3 was pressurized (30 MPa) and saturated with standard oil for 24 hours (the third rock sample could be the first rock sample after the experiment). After the standard white oil filled the pores of the rock sample, it was removed and placed in a nuclear magnetic resonance (NMR) spectrometer for analysis. Low-field NMR testing was performed using the Carr-Purcell-Meiboom-Gill (CPMG) sequence. Measuring the T2 spectrum of a rock sample reveals that longer relaxation times correspond to larger pores. A higher T2 spectrum intensity corresponds to a greater number of pores of that size. Simultaneously, the intensity of the T2 spectrum can be measured, and the porosity (φ) of the rock sample can be calculated based on the correlation between porosity and T2 spectrum intensity.

[0141] The calibration curve is measured before or after the rock sample experiment. Standard samples with different porosities are prepared using the same fluid as the one used for saturated rock samples, and then nuclear magnetic resonance (NMR) experiments are performed to obtain the T2 spectral intensity. The calibration curve is then obtained by fitting the porosity to the T2 spectral intensity.

[0142] Further, 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. 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 each oil content and saturation level.

[0144]

[0145]

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

[0147] In this specific example, the total oil content ranged from 7.2 to 13.4 mg / g rock, with an average of 10.7 mg / g rock. Figure 4 The oil saturation in the pores ranges from 23% to 40%, with an average of 32%. The GOR (Gross Orbit) for the subsurface conditions of this reservoir is taken as 0.4 m. 3 / m 3 The gas saturation ranged from 15.8% to 26.9%, with an average of 21%, while the water saturation ranged from 32.8% to 60.6%, with an average of 47%. Figure 5 ).

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

[0149] The adsorbed oil content ranged from 1.3 to 9 mg / g rock, with an average of 5.3 mg / g rock, accounting for 18% to 67% of the total oil content, with an average of 48%. Figure 6Because the extraction experiment requires sample crushing and heating, hydrocarbons volatilize. However, the NMR experiment does not involve sample crushing and heating, and is shorter in duration, thus avoiding the volatilization of light hydrocarbons and collecting more oil signals. With w o3 The content increased from 1.3 mg / g rock to 9.0 mg / g rock, w o3 / w o1 The coefficient gradually increased, rising from 18% to 68%, with an average of approximately 50%. Figure 6 The volume saturation of adsorbed oil accounted for 8.4%–16.2% of the total porosity, with an average of 15.4%. Figure 7 ).

[0150] The third factor affecting oil content is the adsorption effect of organic matter and clay minerals. o3 Both TOC and clay mineral content showed an upward trend. Figure 8 , Figure 9 Therefore, w o3 Shale oil in layers with high asphalt A content, but also high organic matter and clay mineral content, mainly exists in an adsorbed state and is not easily mobilized. Therefore, it is not possible to rely solely on bitumen A content (w o3 The high level of judgment indicates that it is a good shale oil development zone.

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

[0152] Movable oil content (w) m1 The concentration was 3–7 mg / g rock, with an average of 5.4 mg / g rock, and it decreased with increasing w o3 Increased content leads to decreased mobile oil content. Figure 10 This indicates that mobility is affected by adsorption; the higher the adsorbed oil content, the lower the movable oil content, and so on. A similar pattern applies to the proportion of movable oil (w...). m1 / w o1 With w o3 The content increases and decreases ( Figure 11 ).

[0153] In terms of saturation, the saturation of movable oil is S. m1 The range is 10-32%, with an average of 17%. Figure 12 An increase in total oil saturation indicates higher pore filling and greater mobility. Increased TOC and clay mineral content in shale reservoirs leads to higher mobile oil saturation (S). m1 reduce( Figure 13 , Figure 14This indicates that organic matter and clay minerals have a strong adsorption capacity for shale oil, thus hindering its mobility. However, since low TOC content reduces crude oil production and total oil content, TOC cannot be too low. Therefore, medium-to-high TOC content and low clay mineral content are the most favorable mobility oil-bearing zones.

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

[0155] Free oil content (w) m2 The free oil content was 2.48%-4.52 mg / g rock. m2 / w o1 The percentages ranged from 24% to 36%, with an average of 29%. Figure 15 Free oil saturation (S) m2 The free oil content is 7-10%, averaging 9%. Considering that the current recovery rate of shale oil production areas is less than 10%, the free oil content is closest to the oil produced in the oilfield. The average oil saturation of the pores is 32%, and the mobile oil saturation is 17%. Mobile oil accounts for about half of the total oil, and free oil accounts for about one-quarter. Figure 16 ).

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

[0157] Since the T2 spectrum is proportional to the pore diameter, the increasing T2 value also reflects the variation in pore size. Shale reservoir porosity is bimodal, ranging from 0.01 to 10 ms and from 10 ms to 200 ms. Oil occurrence is also bimodal, with the main occurrence pore sizes being smaller, in the range of 0.01-1 ms. Larger pores around 10 ms during long relaxation are less common. Since small pores are filled with oil, it is inferred that gas and water occur in larger pores greater than 0.2 ms. Figure 17 ).

[0158] Oil within small pores is also mobile; oil within the range of 0.01-1 ms can be lost after sample fragmentation. Figure 18 Most samples indicate that volatile light hydrocarbons are uniformly distributed within the pores. Oil can be produced not only in long T2 pores, but also in other areas. Traditional methods use the T2 cutoff value to distinguish movable oil, assuming that larger pores with longer relaxation times (greater than the T2 cutoff value) represent movable oil. This method is flawed, easily overlooking the contribution of short relaxation times or small pores to oil production. Shale oil is often extracted using horizontal wells for pressure exhaustion. These wells connect fractures, large pores, and some small pores. During extraction, pressure is released, causing oil expansion. Because large and small pores are interconnected, oil can be discharged from both.

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

[0160] like Figure 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 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 low-field nuclear magnetic resonance testing of a first rock sample, the second oil content is obtained by low-field nuclear magnetic resonance testing of a second rock sample, and the third oil content is obtained by solvent extraction of a second rock sample, the first rock sample is an original rock sample, and the second sample is a crushed rock sample;

[0162] Based on the oil content of the rock samples, calculate the mobility evaluation parameters for the first shale oil; and

[0163] Based on the oil saturation of the rock sample, the mobility evaluation parameters for the second shale oil were 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] Based on 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 For the first oil saturation, w o1 The first oil content, ρ rock ρ is the rock density, φ is the porosity, and ρ is the density of the rock. oil The density of shale oil;

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

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

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

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

[0173] The first shale oil mobility evaluation parameters are mobile oil content and / or free oil content;

[0174] The second shale oil mobility evaluation parameters are mobile oil saturation and / or free oil saturation.

[0175] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0176] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0177] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0178] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified 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] Memory may include non-persistent memory in computer-readable media, such as random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM. Memory is an example of computer-readable media.

[0181] Computer-readable media includes both permanent and non-permanent, removable and non-removable media that can store information using any method or technology. Information can be computer-readable instructions, data structures, modules of programs, 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 technologies, CD-ROM, digital versatile optical disc (DVD) or other optical storage, magnetic tape, magnetic magnetic disk storage or other magnetic storage devices, or any other non-transferable medium that can be used to store information accessible by a computing device. As defined herein, computer-readable media does not include transient computer-readable media, such as modulated data signals and carrier waves.

[0182] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0183] The above are merely embodiments of this application and are not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. A method for evaluating the quantity and mobility of shale oil, characterized in that, The method includes: The oil content and porosity of the rock sample are obtained, and the oil saturation of the rock sample is calculated based on the oil content and porosity. Based on the oil content of the rock sample, calculate the mobility evaluation parameters for the first shale oil. Based on the oil saturation of the rock sample, calculate the mobility evaluation parameters for the second shale oil. The mobility of shale oil is evaluated based on the first shale oil mobility evaluation parameter and the second shale oil mobility evaluation parameter. The oil content includes a first oil content, a second oil content, and a third oil content. The first oil content is obtained from a first rock sample based on low-field nuclear magnetic resonance (NMR) testing. The second oil content is obtained from a second rock sample based on low-field NMR testing. The third oil content is obtained from a second rock sample based on solvent extraction. The first rock sample is a pristine rock sample, and the second rock sample is a crushed rock sample. The oil saturation includes a first oil saturation, a second oil saturation, and a third oil saturation; the oil saturation of the rock sample is calculated using the following formula based on the oil content and porosity: S o1 =w o1 ×ρ rock / (φ×ρ oil )×100% In the formula, S o1 For the first oil saturation, w o1 The first oil content, ρ rock ρ is the rock density, φ is the porosity, and ρ is the density of the rock. oil The density of shale oil; S o2 =w o2 ×ρ rock / (φ×ρ oil )×100% In the formula, S o2 For the second oil saturation, w o2 The second oil content, ρ rock ρ is the rock density, φ is the porosity, and ρ is the density of the rock. oil The density of shale oil; S o3 =w o3 ×ρ rock / (φ×ρ oil )×100% In the formula, S o3 The third oil saturation, w o3 The third oil content, ρ rock ρ is the rock density, φ is the porosity, and ρ is the density of the rock. oil For shale oil density, The mobility evaluation parameters for the first shale oil are movable oil content and free oil content; the mobility evaluation parameters for the second shale oil are movable oil saturation and free oil saturation. 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. The difference between the first oil saturation and the second oil saturation is taken as the free oil saturation.

2. The method for evaluating the quantity and mobility of shale oil according to claim 1, characterized in that, The porosity was obtained from a third rock sample based on low-field nuclear magnetic resonance testing, and the third rock sample was a saturated rock sample.

3. The method for evaluating the quantity and mobility of shale oil according to claim 1, characterized in that, The method further includes: Substituting the first oil saturation into the following formula, we obtain the gas saturation: S g =S o1 ×GOR / (1-GOR)×100% In the formula, S g S represents the gas saturation level. o1 First oil saturation, GOR is the gas-oil ratio of the reservoir's subsurface conditions.

4. The method for evaluating the quantity and mobility of shale oil according to claim 3, characterized in that, The method further includes: Substituting the first oil saturation and gas saturation into the following formula, we obtain the water saturation: S w =100-S o1 -S g In the formula, S w S represents the water saturation level. o1 First oil saturation, S g GOR represents the gas saturation level, and GOR represents the gas-oil ratio under the subsurface conditions of the reservoir.

5. A device for evaluating the quantity and mobility of shale oil, 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 to calculate the oil saturation of the rock sample based on the oil content and porosity. Based on the oil content of the rock sample, calculate the mobility evaluation parameters for the first shale oil. And based on the oil saturation of the rock samples, calculate the mobility evaluation parameters for the second shale oil; The oil content includes a first oil content, a second oil content, and a third oil content. The first oil content is obtained from a first rock sample based on low-field nuclear magnetic resonance testing. The second oil content is obtained from a second rock sample based on low-field nuclear magnetic resonance testing. The third oil content is obtained from a second rock sample based on solvent extraction. The first rock sample is a raw rock sample, and the second rock 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. The oil saturation includes a first oil saturation, a second oil saturation, and a third oil saturation; the oil saturation of the rock sample is calculated using the following formula based on the oil content and porosity: S o1 =w o1 ×ρ rock / (φ×ρ oil )×100% In the formula, S o1 For the first oil saturation, w o1 The first oil content, ρ rock ρ is the rock density, φ is the porosity, and ρ is the density of the rock. oil The density of shale oil; S o2 =w o2 ×ρ rock / (φ×ρ oil )×100% In the formula, S o2 For the second oil saturation, w o2 The second oil content, ρ rock ρ is the rock density, φ is the porosity, and ρ is the density of the rock. oil The density of shale oil; S o3 =w o3 ×ρ rock / (φ×ρ oil )×100% In the formula, S o3 The third oil saturation, w o3 The third oil content, ρ rock ρ is the rock density, φ is the porosity, and ρ is the density of the rock. oil For shale oil density, The mobility evaluation parameters for the first shale oil are movable oil content and free oil content; the mobility evaluation parameters for the second shale oil are movable oil saturation and free oil saturation. 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. The difference between the first oil saturation and the second oil saturation is taken as the free oil saturation.

6. The shale oil quantity and mobility evaluation device according to claim 5, characterized in that, The computing module is also used for: Substituting the first oil saturation into the following formula, we obtain the gas saturation: S g =S o1 ×GOR / (1-GOR)×100% In the formula, S g S represents the gas saturation level. o1 First oil saturation, GOR is the gas-oil ratio of the reservoir's subsurface conditions.

7. The shale oil quantity and mobility evaluation device according to claim 6, characterized in that, The computing module is also used for: Substituting the first oil saturation and gas saturation into the following formula, we obtain the water saturation: S w =100-S o1 -S g In the formula, S w S represents the water saturation level. o1 First oil saturation, S g GOR represents the gas saturation level, and GOR represents the gas-oil ratio under the subsurface conditions of the reservoir.

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