An apparatus and method for measuring adsorbed oil content and composition in reservoir pores

Abstract

The application discloses a device for measuring the content and components of adsorbed oil in reservoir pores, and belongs to the technical field of oil and gas field development. The device comprises a temperature sensor and a pressure sensor, and is characterized in that the device further comprises a magnetic suspension balance, a gas chromatograph analyzer, a constant-temperature sealed cabinet, a constant-temperature distillation tube, a vacuum pumping device, a dryer and a pressurizing pump. The dryer is arranged between the constant-temperature sealed cabinet and the constant-temperature distillation tube. The pressurizing pump is arranged on a connecting pipeline between the constant-temperature sealed cabinet and the constant-temperature distillation tube. The pressurizing pump is used for increasing the steam pressure of crude oil in the constant-temperature sealed cabinet to a set pressure. The temperature sensor is used for measuring the temperature in the constant-temperature sealed cabinet. The pressure sensor is used for measuring the steam pressure of crude oil in the constant-temperature sealed cabinet. The application can obtain the proportion of different components of crude oil in adsorbed oil, provide more accurate adsorbed oil component proportion information, and further guarantee the measurement accuracy of the content of adsorbed oil in pores with different diameters in shale.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oil and gas field development, and particularly relates to a device and method for measuring adsorbed oil content and components in a reservoir pore. BACKGROUND

[0002] Shale oil is a collection of liquid hydrocarbons mainly in adsorbed state, free state and mutual state in shale and carbonate rock interbeds or clastic rock interbeds in shale. At present, the method for measuring free oil content in shale is relatively mature, but adsorbed oil in shale still accounts for a large part of total oil content in shale, and shale oil reserves submission, zone evaluation and development plan still need shale adsorbed oil content data as support, so how to obtain accurate shale core adsorbed oil content data through experimental means is the basis for shale oil exploration and development.

[0003] Due to great differences between surface and underground conditions, the content and composition of shale adsorbed oil will be scattered to different degrees in the process of extraction from the bottom of the well to the top of the well, therefore, analyzing the adsorbed oil content remaining in the shale core will inevitably deviate from the true situation, and there is no particularly significant boundary between adsorbed shale oil and free shale oil, and shale oil composition is complex, which is a complex compound of hydrocarbons and resin, asphaltene, which leads to great difficulty in measuring adsorbed shale oil content in the reservoir. At present, the commonly used traditional experimental methods are swelling experiment method and heating release method.

[0004] Swelling experiment method: this method first dissolves crude oil or asphalt in an organic solvent such as toluene, and after the shale sample is placed in the solution for a period of time, the change in absorbance of the solution is detected by spectroscopic method to determine the adsorption amount of shale on crude oil or asphalt, and the adsorption characteristics of shale are evaluated by establishing the relationship between adsorption amount and equilibrium time to determine the adsorbed oil content.

[0005] Heating release method: under the conditions of pyrolysis temperature of 200℃, 350℃, 450℃, 600℃, pyrolysis parameters S1-1, S1-2, S2-1, S2-2 content are measured in turn, and S1-1 and S1-2 content is considered to represent the content of non / weak polar free state compounds, S2-1 is mainly heavy hydrocarbon and polar stronger resin, asphalt adsorbed state components, and S2-2 is mainly kerogen cracking hydrocarbon components, and this method provides the possibility for quantitative evaluation of shale oil adsorption in the laboratory.

[0006] However, the swelling experiment method can analyze the content of adsorbed oil absorbed by shale through spectroscopy and analyze the component characteristics of the adsorbed oil, but there is interaction between the prepared crude oil, asphalt and toluene solution, in general, the stronger the interaction between the selected crude oil, asphalt and toluene, the more uniform the solution mixture, the more conducive to ensuring the uniformity of the adsorption process of the core sample, but the stronger the interaction, the more it inhibits the adsorption of crude oil and asphalt from the solution by the core sample, thereby affecting the total adsorption amount. The most commonly used experimental method for identifying the content of free oil and adsorbed oil in shale reservoirs, namely the heating release method, is widely used in shale oil exploration in many basins in China, but there are also problems. Since there is no significant difference in the composition of free oil and adsorbed oil, only the occurrence mode is different, and the heating release method releases different polar oil components at different temperatures by setting different heating temperatures. According to the different oil components released at different temperatures, the components are divided into free oil and adsorbed oil and their respective contents are calculated, but it cannot be determined whether the hydrocarbons released at a certain temperature are free oil or adsorbed oil.

[0007] These shortcomings of the swelling experiment method and the heating release method affect the reliability of the adsorbed oil content data obtained from the shale oil reservoirs by relying on the prior art solutions, thereby adversely affecting the evaluation and reserve calculation of shale oil reservoirs. In addition, the existing technical solutions cannot simultaneously consider the relationship between the adsorbed oil content and the adsorbed oil components in shale oil reservoirs, and cannot provide experimental data support on the occurrence mechanism of shale oil for shale oil mobility research.

[0008] The Chinese patent document with publication number CN115701640A and publication date of February 10, 2023 discloses a molecular simulation method for calculating the content of adsorbed oil in shale, which includes the following steps:

[0009] (1) Obtain the mineral component information, kerogen information and shale oil component information contained in different shale samples, and the specific surface area and pore structure information of the shale samples;

[0010] (2) Select representative indicators in the obtained mineral component information, kerogen information, shale oil component information and specific surface area and pore structure information of the shale samples, respectively, and establish a molecular model for simulating the corresponding shale sample according to the representative indicators;

[0011] (3) Perform molecular dynamics simulation of different shale samples under different temperature, pressure, specific surface area and pore structure conditions using the molecular model established in step (2), obtain the shale oil adsorption density of the shale samples under different temperature, pressure, specific surface area and pore structure conditions, and establish a relationship model between the adsorbed oil content and the mineral components, kerogen and specific surface area of the shale samples;

[0012] (4) According to the actual measurement results of the laboratory, the relationship model obtained in step (3) is corrected to obtain a correction factor and a shale oil adsorption amount calculation model relationship, and the oil adsorption amount of the shale is calculated.

[0013] The molecular simulation method for calculating the adsorbed oil content in shale disclosed in the patent document establishes a theoretical calculation model, which can be applied to different geological conditions in the absence of samples, and has important significance for the evaluation of overseas shale oil and gas resource potential. However, since the proportion of different components in the crude oil in the adsorbed oil cannot be obtained, more accurate adsorbed oil component ratio information cannot be provided, which affects the measurement accuracy of the adsorbed oil content data in the pores of different diameters in the shale. SUMMARY

[0014] In order to overcome the defects of the prior art, the present application provides a device and method for measuring the adsorbed oil content and components in the reservoir pores, which can obtain the proportion of different components in the crude oil in the adsorbed oil, provide more accurate adsorbed oil component ratio information, and further ensure the measurement accuracy of the adsorbed oil content data in the pores of different diameters in the shale.

[0015] The present application is realized by the following technical solutions:

[0016] A device for measuring the adsorbed oil content and components in the reservoir pores, comprising a temperature sensor and a pressure sensor, characterized in that it further comprises a magnetic suspension balance, a gas chromatograph analyzer, a constant temperature sealed cabinet, a constant temperature distillation tube, a vacuum pumping device, a dryer and a pressure pump, the dryer is arranged between the constant temperature sealed cabinet and the constant temperature distillation tube, and the dryer is used to remove water vapor generated by heating the crude oil, the magnetic suspension balance is used to detect the change in the mass of the shale sample before and after the sample adsorbs the crude oil vapor under different relative pressures, the gas chromatograph analyzer is used to detect the shale oil vapor components in the constant temperature distillation tube and the constant temperature sealed cabinet at different temperatures, the constant temperature distillation tube is used to hold liquid crude oil and evaporate the liquid crude oil into gas, the vacuum pumping device is used to pump out the air in the constant temperature sealed cabinet and the constant temperature distillation tube, the pressure pump is arranged on the connecting pipeline between the constant temperature sealed cabinet and the constant temperature distillation tube, and the pressure pump is used to raise the pressure of the crude oil vapor in the constant temperature sealed cabinet to a set pressure, the temperature sensor is used to measure the temperature in the constant temperature sealed cabinet, and the pressure sensor is used to measure the pressure of the crude oil vapor in the constant temperature sealed cabinet.

[0017] The gas chromatograph analyzer comprises a chromatographic column and a detector, and the detector is a flame ionization detector or a flame thermal ionization detector.

[0018] The constant temperature sealed cabinet is provided with a warehouse opening for loading the shale sample.

[0019] The constant temperature of the constant temperature sealed cabinet is -20-100 DEG C.

[0020] The constant-temperature sealed cabinet has a pressure bearing of 10 MPa.

[0021] The pressure sensor has a measurement range of -100 KPa-10 MPa and an accuracy of 0.01 KPa.

[0022] The constant-temperature distillation tube has a constant-temperature temperature of -20-100℃.

[0023] The constant-temperature distillation tube has a capacity of 100 ml and a pressure bearing of 5 MPa.

[0024] The pressurizing pump has an accuracy of 0.01 KPa.

[0025] A method for measuring the content and components of adsorbed oil in a reservoir pore, characterized in that it comprises the following steps:

[0026] S1, selecting a shale sample of a shale oil reservoir, crushing the shale sample into particles with a particle size of 100-150 μm, and weighing 10-20 g of the particle sample;

[0027] S2, washing the shale sample, measuring the pore volume and pore size distribution of the shale sample;

[0028] S3, taking 50-100 ml of a crude oil sample, measuring the saturated vapor pressure of the crude oil sample, and recording it as P0;

[0029] S4, taking another 50-100 ml of a crude oil sample, measuring the critical temperature of the crude oil sample, and recording it as T0;

[0030] S5, taking another 50-100 ml of a crude oil sample, loading it into a constant-temperature distillation tube, setting the constant-temperature temperature of the constant-temperature distillation tube to T0, calibrating a magnetic suspension balance, and placing 10-20 g of the washed shale sample on the magnetic suspension balance;

[0031] S6, closing the connecting pipeline between the constant-temperature distillation tube and the constant-temperature sealed cabinet, setting the constant-temperature temperature of the constant-temperature sealed cabinet to T0, and simultaneously opening the vacuum pumping device to pump the constant-temperature sealed cabinet to a pressure lower than -100 KPa;

[0032] S7, measuring the mass of the shale sample without adsorbed oil by the magnetic suspension balance ;

[0033] S8, pumping the constant-temperature distillation tube to a vacuum by the vacuum pumping device, evaporating the crude oil in the constant-temperature distillation tube at the critical temperature and low pressure, connecting a gas chromatograph analyzer, and continuously detecting the components of the crude oil vapor;

[0034] S9, when the air in the constant temperature distillation tube is exhausted and the components of the crude oil vapor detected by the gas chromatograph analyzer are fixed, the constant temperature distillation tube is connected with the constant temperature sealed cabinet, and the pressurizing pump is used to make the crude oil vapor in the constant temperature distillation tube enter the constant temperature sealed cabinet according to the set pressure, and is adsorbed on the surface of the shale sample;

[0035] S10, when the pressure of the crude oil vapor in the constant temperature sealed cabinet reaches the set pressure, stop pressurizing, keep the crude oil vapor adsorbed on the surface of the shale sample, detect the components of the crude oil vapor in the constant temperature sealed cabinet by the gas chromatograph analyzer, and observe the pressure of the crude oil vapor in the constant temperature sealed cabinet, when the saturated vapor pressure in the constant temperature sealed cabinet changes by not more than 0.05 KPa within 30 min, record the mass of the shale sample and the pressure P2 of the crude oil vapor, detect the components of the crude oil vapor in the constant temperature sealed cabinet by the gas chromatograph analyzer;

[0036] S11, continue to increase the pressure of the crude oil vapor in the constant temperature sealed cabinet by the pressurizing pump, and repeat step S10, record the mass of the shale sample at each set pressure point and the saturated vapor pressure P i of the i component in the crude oil sample, detect the components of the crude oil vapor in the constant temperature sealed cabinet by the gas chromatograph analyzer, until P i =P0, and record the mass of the shale sample when the shale oil is saturated and adsorbed ;

[0037] S12, take the shale sample out of the constant temperature sealed cabinet, measure the mass of the shale sample saturated with crude oil, denoted as m2, measure the pore volume and pore size distribution of the shale sample saturated with crude oil;

[0038] S13, calculate the adsorbed oil content of the shale sample by formula 1;

[0039] Formula 1

[0040] Wherein:

[0041] Q is the adsorbed oil content of the shale sample, in mg / g;

[0042] m2 is the mass of the shale sample when the shale oil is saturated and adsorbed, in g;

[0043] m1 is the mass of the shale sample without adsorbed oil, in g;

[0044] S14, the pressure collected by the pressure sensor at different test pressure points is corresponding to the gas chromatograph analyzer at the pressure, the pressure value corresponding to the change of different components in the chromatographic column is analyzed, and the adsorbed oil content of different components is calculated by formula 2;

[0045] Formula 2

[0046] Wherein:

[0047] Q i is the adsorbed oil content of the i-th component in the shale sample, in mg / g;

[0048] is the mass of the shale sample when saturated with adsorbed shale oil, in g;

[0049] is the adsorbed oil mass measured at the i-th pressure point in the shale sample, in g;

[0050] is the adsorbed oil mass measured at the i-1-th pressure point in the shale sample, in g;

[0051] S15, obtaining the lower limit of the minimum adsorbed pore size of the i-th component in the shale sample according to the Kelvin equation and the Halsey equation;

[0052] )+ [-5 / ln(P i / P0)] 1 / 3 Formula 3

[0053] Wherein:

[0054] is the lower limit of the minimum adsorbed pore size of the i-th component in the shale sample, in nm;

[0055] is the saturated vapor pressure of the i-th component in the crude oil sample, in MPa;

[0056] P0 is the saturated vapor pressure of the crude oil sample, in MPa;

[0057] S16, obtaining the oil saturation of the shale sample when the adsorbed oil is saturated according to the pore volume of the shale sample before the experiment and the pore volume of the shale sample saturated with crude oil;

[0058] Formula 4

[0059] Wherein:

[0060] S h is the oil saturation of the shale sample when the adsorbed oil is saturated, in %;

[0061] V t is the pore volume of the pores in the shale sample not occupied by adsorbed oil after the shale sample is saturated with crude oil, in ml / g;

[0062] V1 is the pore volume measured after the shale sample is washed with oil, and the unit is ml / g.

[0063] The beneficial effects of the present application mainly manifest in the following aspects:

[0064] 1、Compared with the prior art, the present application can obtain the proportion of different components in the adsorbed oil in the crude oil by detecting the change of the gas chromatography data of the crude oil steam before and after adsorption, provide more accurate adsorbed oil component ratio information, and further ensure the measurement accuracy of the adsorbed oil content data in the pores of different pore sizes in the shale.

[0065] 2、The present application can evaporate liquid crude oil into crude oil steam, and make the crude oil steam adsorb on the surface of the shale sample, analyze the shale adsorbed oil content by detecting the mass change of the shale sample before and after adsorption, and further judge the adsorption of different components of the crude oil in the shale sample according to the change of the gas chromatography analysis results of the crude oil steam before and after adsorption, and obtain the component information of the adsorbed oil of different components in the shale.

[0066] 3、The present application can extract the air in the constant-temperature sealed cabinet, constant-temperature distillation tube and connecting pipeline before the experiment, prevent air interference in measuring the adsorbed oil content and adsorbed oil component, and is beneficial to improve the measurement accuracy.

[0067] 4、Compared with the Chinese patent document with publication number CN115701640A and publication date of February 10, 2023, the shale oil steam formed by evaporation in a high-vacuum environment is adsorbed on the surface of the shale, and is isolated from the external environment, which not only prevents the moisture or nitrogen in the air from interfering with the crude oil adsorption experiment and affecting the experimental results, but also avoids direct heating to crack the kerogen in the shale, destroy the pore structure of the rock, and increase the pore volume of the shale, so as to ensure the measurement accuracy of the shale adsorbed oil content.

[0068] 5、The present application can obtain the adsorbed oil content data in the pores of different pore sizes in the shale and the lower limit of the adsorbed oil occurrence pore diameter of different components by using the capillary condensation phenomenon, and provides more comprehensive information.

[0069] 6、The present application obtains the oil saturation of the shale adsorbed oil through the change of the pore volume of the shale pores before and after the adsorption experiment, obtains multiple experimental data through one experiment, and improves the experimental efficiency.

[0070] 7、The present application can truly reflect the component characteristics of the adsorbed crude oil occurring in the pore space of different pore sizes in the shale by connecting the gas chromatography analyzer, and ensures the measurement accuracy.

[0071] 8. This invention allows crude oil vapor to evaporate into gas under a high vacuum environment and then adsorb onto the shale surface, thus preserving the original component characteristics of the crude oil to the greatest extent and avoiding the impact of the loss of light components during crude oil distillation on the analysis of adsorbed oil components.

[0072] 9. This invention, by designing different adsorption pressure points and analyzing the compositional changes of shale oil vapors of different components at these pressure points, can obtain the lower limit of the minimum occurrence pore size of shale oil of different components; by analyzing the mass change of shale samples before and after adsorption to determine the adsorbed oil content, it can obtain data on the adsorbed oil content in different pore sizes.

[0073] 10. This invention uses a gas chromatograph to analyze the component types and mass fractions of crude oil before and after vapor adsorption, thereby obtaining component characteristic information of oils with different adsorbed components. Detailed Implementation

[0074] Example 1

[0075] An apparatus for measuring the content and composition of adsorbed oil in reservoir pores includes a temperature sensor, a pressure sensor, a magnetic levitation balance, a gas chromatograph, a thermostatic sealed cabinet, a thermostatic distillation tube, a vacuum device, a dryer, and a pressure pump. The dryer is positioned between the thermostatic sealed cabinet and the thermostatic distillation tube and is used to remove water vapor generated during heating of crude oil. The magnetic levitation balance is used to detect changes in the mass of shale samples before and after adsorbing crude oil vapor under different relative pressures. The gas chromatograph is used to detect the composition of shale oil vapor in the thermostatic distillation tube and the thermostatic sealed cabinet at different temperatures. The thermostatic distillation tube is used to hold liquid crude oil and evaporate it into a gaseous state. The vacuum device is used to extract air from the thermostatic sealed cabinet and the thermostatic distillation tube. The pressure pump is located on the connecting pipeline between the thermostatic sealed cabinet and the thermostatic distillation tube and is used to increase the pressure of crude oil vapor in the thermostatic sealed cabinet to a set pressure. The temperature sensor is used to measure the temperature in the thermostatic sealed cabinet, and the pressure sensor is used to measure the pressure of crude oil vapor in the thermostatic sealed cabinet.

[0076] This embodiment is the most basic implementation method. Compared with the prior art, by detecting the changes in gas chromatography data of crude oil vapor before and after adsorption, the proportion of different components in crude oil in the adsorbed oil can be obtained, providing more accurate information on the proportion of adsorbed oil components, thereby ensuring the measurement accuracy of adsorbed oil content data in pores of different sizes in shale.

[0077] Example 2

[0078] The device for measuring the adsorbed oil content and components in the reservoir pores comprises a temperature sensor, a pressure sensor, a magnetic suspension balance, a gas chromatograph analyzer, a constant-temperature sealed cabinet, a constant-temperature distillation tube, a vacuumizing device, a dryer and a pressurizing pump, the dryer is arranged between the constant-temperature sealed cabinet and the constant-temperature distillation tube, the dryer is used for removing water vapor generated by heating crude oil, the magnetic suspension balance is used for detecting the mass change of the shale sample before and after the shale sample adsorbs crude oil vapor under different relative pressures, the gas chromatograph analyzer is used for detecting the shale oil vapor components in the constant-temperature distillation tube and the constant-temperature sealed cabinet at different temperatures, the constant-temperature distillation tube is used for containing liquid crude oil and evaporating the liquid crude oil into gaseous state, the vacuumizing device is used for extracting air in the constant-temperature sealed cabinet and the constant-temperature distillation tube, the pressurizing pump is arranged on a connecting pipeline between the constant-temperature sealed cabinet and the constant-temperature distillation tube, and the pressurizing pump is used for increasing the pressure of the crude oil vapor in the constant-temperature sealed cabinet to a set pressure, the temperature sensor is used for measuring the temperature in the constant-temperature sealed cabinet, and the pressure sensor is used for measuring the pressure of the crude oil vapor in the constant-temperature sealed cabinet.

[0079] Further, the gas chromatograph analyzer comprises a chromatographic column and a detector, and the detector is a flame ionization detector. The constant-temperature sealed cabinet is provided with a loading opening for loading the shale sample. The constant-temperature temperature of the constant-temperature sealed cabinet is -20-100 DEG C. The pressure bearing of the constant-temperature sealed cabinet is 10 MPa. The measurement range of the pressure sensor is -100 KPa-10 MPa, and the accuracy is 0.01 KPa. The constant-temperature temperature of the constant-temperature distillation tube is -20-100 DEG C. The capacity of the constant-temperature distillation tube is 100 ml, and the pressure bearing is 5 MPa. The accuracy of the pressurizing pump is 0.01 KPa.

[0080] The embodiment is a preferred implementation, which can evaporate liquid crude oil into crude oil vapor, and make the crude oil vapor adsorbed on the surface of the shale sample. The adsorbed oil content of the shale is analyzed by detecting the mass change of the shale sample before and after the adsorption. Then, the adsorption of different components of the crude oil in the shale sample is judged according to the change of the gas chromatograph analysis results of the crude oil vapor before and after the adsorption, and the component information of the adsorbed oil of different components in the shale is obtained.

[0081] Embodiment 3

[0082] A method for measuring the adsorbed oil content and components in the reservoir pores comprises the following steps.

[0083] S1, selecting a shale sample of a shale oil reservoir, crushing the shale sample into particles with a particle size of 100 μm, and weighing 10 g of the particle sample;

[0084] S2, washing the shale sample, and measuring the pore volume and pore size distribution of the shale sample;

[0085] S3, take 50 ml of crude oil sample, measure the saturated vapor pressure of the crude oil sample, recorded as P0;

[0086] S4, take another 50 ml of crude oil sample, measure the critical temperature of the crude oil sample, recorded as T0;

[0087] S5, take another 50 ml of crude oil sample, put it into the constant temperature distillation tube, set the constant temperature of the constant temperature distillation tube to T0, calibrate the magnetic suspension balance, and put 10 g of shale sample after washing oil on the magnetic suspension balance;

[0088] S6, close the connecting pipeline between the constant temperature distillation tube and the constant temperature sealed cabinet, set the constant temperature of the constant temperature sealed cabinet to T0, and open the vacuum device to vacuumize the constant temperature sealed cabinet until the pressure in the constant temperature sealed cabinet is lower than -100 KPa;

[0089] S7, measure the mass of the shale sample without adsorbed oil by the magnetic suspension balance ;

[0090] S8, vacuumize the constant temperature distillation tube by the vacuum device, so that the crude oil in the constant temperature distillation tube evaporates at the critical temperature and low pressure, connect the gas chromatograph analyzer, and continuously detect the components of the crude oil vapor;

[0091] S9, when the air in the constant temperature distillation tube is exhausted and the components of the crude oil vapor detected by the gas chromatograph analyzer are fixed and unchanged, connect the constant temperature distillation tube and the constant temperature sealed cabinet, use the pressurizing pump to make the crude oil vapor in the constant temperature distillation tube enter the constant temperature sealed cabinet according to the set pressure, and adsorb on the surface of the shale sample;

[0092] S10, when the pressure of the crude oil vapor in the constant temperature sealed cabinet reaches the set pressure, stop pressurizing, keep the crude oil vapor adsorbed on the surface of the shale sample, detect the components of the crude oil vapor in the constant temperature sealed cabinet by the gas chromatograph analyzer, and observe the pressure of the crude oil vapor in the constant temperature sealed cabinet, when the saturated vapor pressure in the constant temperature sealed cabinet changes by not more than 0.05 KPa within 30 min, record the mass of the shale sample and the pressure P2 of the crude oil vapor, detect the components of the crude oil vapor in the constant temperature sealed cabinet by the gas chromatograph analyzer;

[0093] S11, continue to increase the pressure of the crude oil vapor in the constant temperature sealed cabinet by the pressurizing pump, repeat step S10, and record the mass of the shale sample and the saturated vapor pressure P i of the i component in the crude oil sample at each set pressure point; i , detect the components of the crude oil vapor in the constant temperature sealed cabinet by the gas chromatograph analyzer, until P ;

[0094] S12, the shale sample is taken out from the constant temperature sealed cabinet, the mass of the shale sample saturated with crude oil is measured and recorded as m2, the pore volume and pore size distribution of the shale sample saturated with crude oil are measured;

[0095] S13, the adsorbed oil content of the shale sample is calculated by formula 1;

[0096] Formula 1

[0097] Wherein:

[0098] Q is the adsorbed oil content of the shale sample, in mg / g;

[0099] m2 is the mass of the shale sample saturated with adsorbed shale oil, in g;

[0100] m1 is the mass of the shale sample without adsorbed oil, in g;

[0101] S14, the pressure collected by the pressure sensor at different test pressure points is corresponded to the gas chromatograph analysis at the pressure, the pressure value corresponding to the change of different components in the chromatographic column is analyzed, and the adsorbed oil content of different components is calculated by formula 2;

[0102] Formula 2

[0103] Wherein:

[0104] Q i Qi is the adsorbed oil content of the i component in the shale sample, in mg / g;

[0105] m2 is the mass of the shale sample saturated with adsorbed shale oil, in g;

[0106] mi is the adsorbed oil mass measured at the i pressure point in the shale sample, in g;

[0107] mi-1 is the adsorbed oil mass measured at the i-1 pressure point in the shale sample, in g;

[0108] S15, the minimum occurrence pore size lower limit of the i component in the shale sample is obtained according to the Kelvin equation and the Halsey equation;

[0109] )+ [-5 / ln(P i / P0)] 1 / 3 Formula 3

[0110] Wherein:

[0111] is the minimum lower limit of the occurrence pore size of the i component in the shale sample, in nm;

[0112] is the saturated steam pressure of the i component in the crude oil sample, in MPa;

[0113] P0 is the saturated steam pressure of the crude oil sample, in MPa;

[0114] S16, according to the pore volume of the shale sample before the experiment and the pore volume of the shale sample saturated with crude oil, the oil saturation of the shale sample when the adsorbed oil is saturated with adsorption is obtained;

[0115] Formula 4

[0116] wherein:

[0117] S h is the oil saturation of the shale sample when the adsorbed oil is saturated with adsorption, in %;

[0118] V t is the pore volume of the pores in the shale sample that are not occupied by adsorbed oil after the shale sample is saturated with crude oil, in ml / g;

[0119] V1 is the pore volume measured after the shale sample is washed clean, in ml / g.

[0120] This embodiment is another preferred implementation. The vacuum device can extract air in the constant-temperature sealed cabinet, the constant-temperature distillation tube and the connecting pipeline before the experiment, prevent air from interfering with the measurement of the adsorbed oil content and the adsorbed oil component, and be beneficial to improving the measurement accuracy.

[0121] Compared with the Chinese patent document with publication number CN115701640A and publication date of February 10, 2023, the shale oil vapor formed by evaporation in a high-vacuum environment is adsorbed on the surface of the shale, and is isolated from the external environment. This not only prevents moisture or nitrogen in the air from interfering with the crude oil adsorption experiment and affecting the experimental results, but also avoids direct heating to cause the cracking of kerogen in the shale, damage the pore structure of the rock, and increase the pore volume of the shale, thereby ensuring the measurement accuracy of the shale adsorbed oil content.

[0122] Example 4

[0123] A method for measuring the content and components of adsorbed oil in reservoir pores, comprising the following steps:

[0124] S1, select a shale sample of a shale oil reservoir, crush the shale sample into particles with a particle size of 150 μm, and weigh 20 g of the particle sample; S2, wash the shale sample with oil, and measure the pore volume and pore size distribution of the shale sample; S3, take 100 ml of a crude oil sample, measure the saturated vapor pressure of the crude oil sample, and record the saturated vapor pressure as P0; S4, take another 100 ml of a crude oil sample, measure the critical temperature of the crude oil sample, and record the critical temperature as T0; S5, take another 100 ml of a crude oil sample, load the crude oil sample into a constant temperature distillation tube, set the constant temperature of the constant temperature distillation tube to T0, calibrate a magnetic suspension balance, and place 20 g of the shale sample washed with oil on the magnetic suspension balance; S6, close the connecting pipeline between the constant temperature distillation tube and the constant temperature sealed cabinet, set the constant temperature of the constant temperature sealed cabinet to T0, and simultaneously open a vacuum pumping device to pump the constant temperature sealed cabinet to a pressure lower than -100 KPa; S7, measure the mass of the shale sample without adsorbed oil by the magnetic suspension balance ; S8, pump the constant temperature distillation tube to a low pressure by the vacuum pumping device, so that the crude oil in the constant temperature distillation tube evaporates at the critical temperature and the low pressure, connect a gas chromatograph analyzer, and continuously detect the components of the crude oil vapor; S9, when the air in the constant temperature distillation tube is exhausted and the components of the crude oil vapor detected by the gas chromatograph analyzer remain unchanged, connect the constant temperature distillation tube and the constant temperature sealed cabinet, use a pressurizing pump to make the crude oil vapor in the constant temperature distillation tube enter the constant temperature sealed cabinet at a set pressure, and be adsorbed on the surface of the shale sample; S10, when the pressure of the crude oil vapor in the constant temperature sealed cabinet reaches the set pressure, stop pressurizing, keep the crude oil vapor adsorbed on the surface of the shale sample, detect the components of the crude oil vapor in the constant temperature sealed cabinet by the gas chromatograph analyzer, and observe the pressure of the crude oil vapor in the constant temperature sealed cabinet; when the saturated vapor pressure in the constant temperature sealed cabinet changes by no more than 0.05 KPa within 30 min, record the mass of the shale sample and the pressure P2 of the crude oil vapor, detect the components of the crude oil vapor in the constant temperature sealed cabinet by the gas chromatograph analyzer; S11, continue to increase the pressure of the crude oil vapor in the constant temperature sealed cabinet by the pressurizing pump, and repeat step S10 to record the mass of the shale sample and the saturated vapor pressure P i of the i-th component in the crude oil sample; detect the components of the crude oil vapor in the constant temperature sealed cabinet by the gas chromatograph analyzer until P i =P0, and record the mass of the shale sample when the shale oil is saturatedly adsorbed ; S12, take the shale sample out of the constant temperature sealed cabinet, measure the mass of the shale sample saturated with the crude oil, and record the mass as m2; measure the pore volume and pore size distribution of the shale sample saturated with the crude oil; S13, calculate the adsorbed oil content of the shale sample by formula 1

[0125] Formula 1

[0126] wherein:

[0127] Q is the adsorbed oil content of the shale sample, in mg / g;

[0128] is the mass of the shale sample when saturated with adsorbed shale oil, in g;

[0129] is the mass of the shale sample without adsorbed oil, in g;

[0130] S14, the pressure collected by the pressure sensor at different test pressure points is corresponded to the gas chromatograph at this pressure, the pressure value corresponding to the change of different components in the chromatographic column is analyzed, and the adsorbed oil content of different components is calculated by formula 2;

[0131] Formula 2

[0132] Wherein:

[0133] Q i is the adsorbed oil content of the i-th component in the shale sample, in mg / g;

[0134] is the mass of the shale sample when saturated with adsorbed shale oil, in g;

[0135] is the adsorbed oil mass measured at the i-th pressure point in the shale sample, in g;

[0136] is the adsorbed oil mass measured at the i-1-th pressure point in the shale sample, in g;

[0137] S15, the minimum pore size lower limit of the i-th component in the shale sample is obtained according to the Kelvin equation and the Halsey equation;

[0138] )+ [-5 / ln(P i / P0)] 1 / 3 Formula 3

[0139] Wherein:

[0140] is the minimum pore size lower limit of the i-th component in the shale sample, in nm;

[0141] is the saturated vapor pressure of the i-th component in the crude oil sample, in MPa;

[0142] P0 is the saturated vapor pressure of the crude oil sample, in MPa;

[0143] S16, obtaining oil saturation of adsorbed oil in the shale sample when the adsorbed oil is saturated, according to the pore volume of the shale sample before the experiment and the pore volume of the shale sample saturated with the crude oil;

[0144] Formula 4

[0145] Wherein:

[0146] S h S is the oil saturation of adsorbed oil in the shale sample when the adsorbed oil is saturated, and the unit is %;

[0147] V t V is the pore volume of the pores not occupied by the adsorbed oil after the shale sample is saturated with the crude oil, and the unit is ml / g;

[0148] V1 is the pore volume measured after the shale sample is washed clean, and the unit is ml / g.

[0149] The present embodiment is the best mode, and the capillary condensation phenomenon can be used to obtain the adsorbed oil content data in pores with different pore diameters in the shale and the lower limit of the pore diameter of the adsorbed oil of different components, and the information provided is more comprehensive.

[0150] The oil saturation of the shale adsorbed oil is obtained through the change of the pore volume of the shale before and after the adsorption experiment, a plurality of experimental data is obtained through one experiment, and the experimental efficiency is improved.

[0151] The component characteristics of the adsorbed crude oil stored in the pore space with different pore diameters in the shale can be truly reflected through the connection of the gas chromatograph, and the measurement accuracy is ensured.

[0152] The crude oil steam is evaporated into gas in a high-vacuum environment and then adsorbed on the shale surface, so that the original component characteristics of the crude oil are retained to the greatest extent, and the influence of the loss of light components in the crude oil distillation process on the component analysis of the adsorbed oil is avoided.

[0153] The minimum lower limit of the pore diameter of different component shale oils can be obtained by designing different adsorption pressure points and analyzing the component change of the shale oil steam of different components at the pressure point; and the adsorbed oil content data in different pore diameters can be obtained by analyzing the adsorbed oil content through the change of the shale sample quality before and after the adsorption.

[0154] The component characteristics information of the adsorbed oil of different components can be obtained by analyzing the component type and mass fraction of the crude oil steam before and after the adsorption through the gas chromatograph.

[0155] The calculation principle of the adsorbed oil content of different components of the present application is as follows:

[0156] The pressure collected by the pressure sensor at different test pressure points is corresponding to the pressure under the gas chromatograph analyzer, the pressure value corresponding to the change of different components in the chromatographic column is analyzed, since the saturated vapor pressure of different components in the crude oil sample is different, at the critical temperature, the component with low saturated vapor pressure is liquefied and adsorbed on the shale surface, and at the same time, the detection peak represented by the component in the crude oil sample vapor disappears, therefore, the adsorbed oil content of different components can be calculated by formula 2;

[0157] Formula 2

[0158] Wherein:

[0159] Q i The adsorbed oil content of the i-th component in the shale sample, unit: mg / g;

[0160] The mass of the shale sample when the shale oil is saturated, unit: g;

[0161] The adsorbed oil mass measured at the i-th pressure point in the shale sample, unit: g;

[0162] The adsorbed oil mass measured at the i-1-th pressure point in the shale sample, unit: g.

[0163] The calculation principle of the minimum occurrence pore size lower limit of the i-th component in the shale sample is as follows:

[0164] At the critical temperature of the crude oil sample, the adsorption of the crude oil sample vapor on the shale surface increases with the increase of P / P0 Capillary condensation phenomenon occurs in the shale pore with different pore sizes, that is, the crude oil sample vapor condenses into liquid crude oil in the pore, and forms a concave liquid surface, and the Capillary pore size is related, therefore, according to the Kelvin equation and the Halsey equation, the minimum occurrence pore size lower limit of the i-th component in the shale sample can be obtained;

[0165] )+ [-5 / ln(P i / P0)] 1 / 3 Formula 3

[0166] Wherein:

[0167] The minimum occurrence pore size lower limit of the i-th component in the shale sample, unit: nm;

[0168] The saturated vapor pressure of the i-th component in the crude oil sample, unit: MPa;

[0169] P0 is the saturated vapor pressure of the crude oil sample in MPa.

Claims

1. A method of measuring adsorbed oil content and composition in reservoir pores, characterized by, The device for measuring the adsorbed oil content and components in the reservoir pores is used for measurement, including the following steps: S1, selecting a shale sample of a shale oil reservoir, crushing the shale sample into particles with a particle size of 100-150 μm, and weighing 10-20 g of the particle sample; S2, washing the shale sample, and measuring the pore volume and pore size distribution of the shale sample; S3, taking 50-100 ml of a crude oil sample, and measuring the saturated vapor pressure of the crude oil sample, denoted as P0; S4, taking another 50-100 ml of a crude oil sample, and measuring the critical temperature of the crude oil sample, denoted as T0; S5, taking another 50-100 ml of a crude oil sample, and loading the sample into a constant temperature distillation tube, setting the constant temperature of the constant temperature distillation tube to T0, calibrating a magnetic suspension balance, and placing 10-20 g of the washed shale sample on the magnetic suspension balance; S6, closing the connecting pipeline between the constant temperature distillation tube and the constant temperature sealed cabinet, setting the constant temperature of the constant temperature sealed cabinet to T0, and simultaneously opening the vacuum pumping device to pump the constant temperature sealed cabinet to a pressure lower than -100 KPa; S7. Measure the mass of the shale sample without adsorbed oil by magnetic suspension balance ; S8, pumping the constant temperature distillation tube to a low pressure by the vacuum pumping device, so that the crude oil in the constant temperature distillation tube evaporates at the critical temperature and the low pressure, connecting a gas chromatograph analyzer, and continuously detecting the components of the crude oil vapor; S9, when the air in the constant temperature distillation tube is exhausted and the components of the crude oil vapor detected by the gas chromatograph analyzer remain unchanged, connecting the constant temperature distillation tube and the constant temperature sealed cabinet, and using a pressurizing pump to make the crude oil vapor in the constant temperature distillation tube enter the constant temperature sealed cabinet at a set pressure, and adsorb on the surface of the shale sample; S10, when the crude oil vapor pressure in the constant temperature sealed cabinet reaches the set pressure, stop pressurizing, keep the crude oil vapor adsorbed on the shale sample surface, detect the components of the crude oil vapor in the constant temperature sealed cabinet by the gas chromatograph analyzer, and observe the crude oil vapor pressure in the constant temperature sealed cabinet; when the saturated vapor pressure in the constant temperature sealed cabinet changes by not more than 0.05 KPa within 30 min, record the mass of the shale sample and the pressure P2 of the crude oil vapor, detect the components of the crude oil vapor in the constant temperature sealed cabinet by the gas chromatograph analyzer; S11, continue to increase the crude oil vapor pressure in the constant temperature sealed cabinet by the pressure pump, repeat step S10, and record the mass of the shale sample at each set pressure point and the saturated vapor pressure P of the i component in the crude oil sample i , detect the components of the crude oil vapor in the constant temperature sealed cabinet by a gas chromatograph until P i = P0, and record the mass of the shale sample when the shale oil is saturatedly adsorbed ; S12, taking the shale sample from the constant temperature sealed cabinet, measuring the mass of the shale sample saturated with the crude oil, denoted as m2, and measuring the pore volume and pore size distribution of the shale sample saturated with the crude oil; S13, calculating the adsorbed oil content of the shale sample by formula 1; Formula 1 Wherein: Q is the adsorbed oil content of the shale sample, in mg / g; mass of the shale sample in g at saturation adsorption of shale oil; Mass of shale sample without adsorbed oil, in g; S14, corresponding the pressure collected by the pressure sensor at different test pressure points to the gas chromatograph analyzer at the pressure, analyzing the pressure values corresponding to the changes of different components in the chromatographic column, and calculating the adsorbed oil content of different components by formula 2; Formula 2 Wherein: Q i Q is the adsorbed oil content of component I in the shale sample in mg / g; mass of shale sample in g; mass of adsorbed oil measured for the i-th pressure point in the shale sample in g; mass of adsorbed oil measured for the i-1th pressure point in the shale sample, in g; S15, obtaining the lower limit of the minimum occurrence pore size of the i component in the shale sample according to the Kelvin equation and the Halsey equation; + [-5 / ln(P i / P0)] 1 / 3 Formula 3 Wherein: Dmin is the minimum occurrence pore diameter limit for Group I components in the shale sample, in nm; S is the saturated vapor pressure of the i-component in the crude oil sample in MPa; P0 is the saturated vapor pressure of the crude oil sample, in MPa; S16, obtaining the oil saturation degree of the shale sample when the adsorbed oil is saturated and adsorbed according to the pore volume of the shale sample before the experiment and the pore volume of the shale sample saturated with the crude oil; Formula 4 Wherein: S h OIL is the oil saturation in the shale sample at the time of adsorption, in %; V t Volumetric capacity of the pores of the shale sample that are occupied by adsorbed oil after saturation of the sample with crude oil, in ml / g; V1 is the pore volume measured after the shale sample is washed clean, in ml / g; The device for measuring the adsorbed oil content and components in the reservoir pores comprises a temperature sensor, a pressure sensor, a magnetic suspension balance, a gas chromatograph analyzer, a constant temperature sealed cabinet, a constant temperature distillation tube, a vacuum pump, a dryer and a pressurizing pump, the dryer is arranged between the constant temperature sealed cabinet and the constant temperature distillation tube, and is used for removing water vapor generated by heating crude oil, the magnetic suspension balance is used for detecting the change in the mass of the shale sample before and after the sample adsorbs crude oil vapor under different relative pressures, the gas chromatograph analyzer is used for detecting the shale oil vapor components in the constant temperature distillation tube and the constant temperature sealed cabinet at different temperatures, the constant temperature distillation tube is used for containing liquid crude oil and evaporating the liquid crude oil into gas, the vacuum pump is used for pumping out air in the constant temperature sealed cabinet and the constant temperature distillation tube, the pressurizing pump is arranged on a connecting pipeline between the constant temperature sealed cabinet and the constant temperature distillation tube, and is used for increasing the pressure of the crude oil vapor in the constant temperature sealed cabinet to a set pressure, the temperature sensor is used for measuring the temperature in the constant temperature sealed cabinet, and the pressure sensor is used for measuring the pressure of the crude oil vapor in the constant temperature sealed cabinet.

2. The method of claim 1, wherein: The gas chromatograph analyzer comprises a chromatographic column and a detector, and the detector is a flame ionization detector or a flame thermal ionization detector.

3. The method of claim 1, wherein: The constant temperature sealed cabinet is provided with a sample loading opening.

4. The method of claim 1, wherein: The constant temperature of the constant temperature sealed cabinet is -20-100 DEG C.

5. The method of claim 1, wherein: The pressure bearing of the constant temperature sealed cabinet is 10 MPa.

6. The method of claim 1, wherein: The measurement range of the pressure sensor is -100 KPa-10 MPa, and the accuracy is 0.01 KPa.

7. The method of claim 1, wherein: The constant temperature of the constant temperature distillation tube is -20-100 DEG C.

8. The method of claim 1, wherein: The capacity of the constant temperature distillation tube is 100 ml, and the pressure bearing is 5 MPa.

9. The method of claim 1, wherein: The accuracy of the pressurizing pump is 0.01 KPa.

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