Device and method for measuring content and components of adsorbed oil in reservoir pores

Abstract

The invention discloses a device for measuring the content and components of adsorbed oil in reservoir pores, which belongs to the technical field of oil-gas field development, comprises a temperature sensor and a pressure sensor, and is characterized by further comprising a magnetic suspension balance, a gas chromatographic analyzer, a constant-temperature sealing cabinet, a constant-temperature distillation tube, a vacuumizing device, a dryer and a booster pump, the dryer is arranged between the constant-temperature sealing cabinet and the constant-temperature distillation pipe, the pressure pump is arranged on a connecting pipeline between the constant-temperature sealing cabinet and the constant-temperature distillation pipe, the pressure pump is used for increasing the steam pressure of crude oil in the constant-temperature sealing cabinet to a set pressure, and the temperature sensor is used for measuring the temperature in the constant-temperature sealing cabinet. And the pressure sensor is used for measuring the crude oil steam pressure in the constant-temperature sealing cabinet. According to the method, the proportions of different components in the crude oil in the adsorbed oil can be obtained, more accurate adsorbed oil component proportion information is provided, and then the measurement precision of adsorbed oil content data in pores with different pore diameters in shale is guaranteed.

Description

Technical Field

[0001] The invention relates to the technical field of oil and gas field development, and in particular to a device and method for measuring the content and components of adsorbed oil in reservoir pores. Background Art

[0002] Shale oil is a collection of liquid hydrocarbons that exist in mud shale and carbonate or clastic interlayers in mud shale in adsorbed, free, or intersoluble states. At present, the determination method of free oil content in shale is relatively mature, but adsorbed oil in shale still accounts for a large part of the total oil content of shale. The submission of shale oil reserves, zone evaluation, and development plan formulation still require shale adsorbed oil content data as support. Therefore, how to obtain accurate adsorbed oil content data of shale cores through experimental means is the basis of shale oil exploration and development.

[0003] Due to the great difference between the conditions on the ground and underground, the content and composition of shale adsorbed oil will escape to varying degrees during the core extraction process from the bottom of the well to the wellhead. Therefore, the analysis of the adsorbed oil content remaining in the shale core is bound to deviate from the actual situation. In addition, there is no particularly significant boundary between adsorbed shale oil and free shale oil. Shale oil has a complex composition, which is a complex compound of hydrocarbons, colloids and asphaltene. This makes it difficult to determine the content of adsorbed shale oil in the reservoir. At present, the commonly used traditional experimental methods are swelling test method and heating release method.

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

[0005] Heating release method: Under the conditions of pyrolysis temperatures of 200℃, 350℃, 450℃ and 600℃, the pyrolysis parameters S1-1, S1-2, S2-1 and S2-2 were measured in turn. It is believed that the contents of S1-1 and S1-2 represent the contents of non- / weakly polar free compounds, S2-1 is mainly heavy hydrocarbons and highly polar colloid and asphaltene adsorbed components, and S2-2 is mainly kerogen cracking hydrocarbon generation components. This method makes it possible to quantitatively evaluate the adsorption capacity of shale oil in the laboratory.

[0006] However, the swelling test method can analyze the adsorbed oil content adsorbed by shale and analyze the component characteristics of the adsorbed oil by spectroscopy. However, there is an interaction between the mixed solution of crude oil, asphalt and toluene. Generally speaking, the stronger the interaction between the selected crude oil, asphalt and toluene, the more uniform the solution mixing, and the more conducive to ensuring the uniformity of the adsorption process of the core sample. However, the stronger the interaction, the more it will inhibit the core sample from adsorbing crude oil and asphalt from the solution, 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 composition between free oil and adsorbed oil, only their occurrence modes are different, and the heating release method sets different heating temperatures to release crude oil components of different polarities at different temperatures. According to the different crude oil components released at different temperatures, the components are divided into free oil and adsorbed oil and their respective contents are calculated. However, it is still unclear whether the thermally released hydrocarbons measured at a certain temperature are all free oil or adsorbed oil.

[0007] These shortcomings of the swelling test method and the heating release method affect the reliability of the adsorbed oil content data in shale oil reservoirs obtained by relying on the existing technical solutions, which in turn has an adverse impact on shale oil reservoir evaluation and reserve calculation. In addition, the existing technical solutions are also unable to simultaneously analyze the relationship between the adsorbed oil content and the adsorbed oil components in shale oil reservoirs, and are unable to provide experimental data support for shale oil mobility research on the storage mechanism of shale oil.

[0008] A Chinese patent document with publication number CN115701640A and publication date of February 10, 2023 discloses a molecular simulation method for calculating the adsorbed oil content in shale, which includes the following steps: (1) Obtaining information on mineral components, kerogen, and shale oil components contained in different shale samples, as well as specific surface area and pore structure information of shale samples; (2) respectively selecting representative indicators of the mineral component information, kerogen information, shale oil component information, specific surface area and pore structure information of the obtained shale samples, and establishing a molecular model simulating the corresponding shale samples according to the representative indicators; (3) using the molecular model established in step (2) to perform molecular dynamics simulations of different shale samples under different temperatures, pressures, specific surface areas and pore structures, to obtain the shale oil adsorption density of the shale samples under different temperatures, pressures, specific surface areas and pore structures, and to establish a relationship model between the amount of adsorbed oil and the mineral composition, kerogen and specific surface area of ​​the shale samples; (4) The relationship model obtained in step (3) is calibrated according to the actual laboratory measurement results, and the correction factor and the relationship between the calculation model of the amount of oil adsorbed by shale are obtained to calculate the amount of oil adsorbed by shale.

[0009] The molecular simulation method for calculating the adsorbed oil content in shale disclosed in the patent document and the theoretical calculation model established can be applied to different geological conditions in the absence of samples, which is of great significance for the evaluation of overseas shale oil and gas resource potential. However, since the proportion of different components in crude oil in the adsorbed oil cannot be obtained, it is impossible to provide more accurate information on the proportion of adsorbed oil components, which affects the measurement accuracy of adsorbed oil content data in pores of different pore sizes in shale. Summary of the invention

[0010] In order to overcome the defects of the above-mentioned prior art, the present invention provides a device and method for measuring the content and components of adsorbed oil in reservoir pores. The present invention can obtain the proportion of different components in crude oil in adsorbed oil, provide more accurate information on the proportion of adsorbed oil components, and thus ensure the measurement accuracy of adsorbed oil content data in pores of different pore sizes in shale.

[0011] The present invention is achieved through the following technical solutions: A device for measuring the adsorbed oil content and components in reservoir pores, comprising a temperature sensor and a pressure sensor, characterized in that it also comprises a magnetic suspension balance, a gas chromatograph, a thermostatic sealed cabinet, a thermostatic distillation tube, a vacuum pump, a dryer and a pressure pump, wherein the dryer is arranged between the thermostatic sealed cabinet and the thermostatic distillation tube, and is used to remove water vapor generated by heating crude oil, the magnetic suspension balance is used to detect the change in sample mass before and after shale samples adsorb crude oil vapor under different relative pressures, the gas chromatograph is used to detect shale oil vapor components in the thermostatic distillation tube and the thermostatic sealed cabinet at different temperatures, the thermostatic distillation tube is used to contain liquid crude oil and evaporate the liquid crude oil into gas, the vacuum pump is used to extract air in the thermostatic sealed cabinet and the thermostatic distillation tube, the pressure pump is arranged on the connecting pipeline between the thermostatic sealed cabinet and the thermostatic distillation tube, and is used to increase the crude oil vapor pressure 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 crude oil vapor pressure in the thermostatic sealed cabinet.

[0012] The gas chromatograph comprises a chromatographic column and a detector, wherein the detector is a flame ionization detector or a flame thermal ionization detector.

[0013] The constant temperature sealed cabinet is provided with a port for loading shale samples.

[0014] The constant temperature of the constant temperature sealing cabinet is -20-100°C.

[0015] The constant temperature sealed cabinet has a pressure bearing capacity of 10 MPa.

[0016] The measuring range of the pressure sensor is -100KPa-10MPa, and the accuracy is 0.01Kpa.

[0017] The constant temperature of the constant temperature distillation tube is -20-100°C.

[0018] The constant temperature distillation tube has a capacity of 100 ml and a pressure resistance of 5 MPa.

[0019] The accuracy of the pressure pump is 0.01 KPa.

[0020] A method for measuring the content and components of adsorbed oil in reservoir pores, characterized by comprising the following steps: S1. Select shale samples from shale oil reservoirs, crush the shale samples into particles with a particle size of 100-150 μm, and weigh 10-20 g of the particle samples; S2, washing the shale sample with oil and measuring the pore volume and pore size distribution of the shale sample; S3, take 50-100 ml of crude oil sample and measure the saturated vapor pressure of the crude oil sample, recorded as P0; S4, take another 50-100 ml crude oil sample and measure the critical temperature of the crude oil sample, which is recorded as T0; S5. Take another 50-100 ml crude oil sample and put it into a constant temperature distillation tube. Set the constant temperature of the constant temperature distillation tube to T0, calibrate the magnetic suspension balance, and take 10-20 g of the shale sample after oil washing and place it 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 turn on the vacuum pumping device to evacuate the constant temperature sealed cabinet until the pressure in the constant temperature sealed cabinet is lower than -100KPa; S7. Measure the mass of shale samples without adsorbed oil by magnetic suspension balance ; S8, evacuating the constant temperature distillation tube by a vacuum pumping device to evaporate the crude oil in the constant temperature distillation tube at a critical temperature and low pressure, connecting a gas chromatograph to continuously detect the components of the crude oil vapor; S9. When the air in the constant temperature distillation tube is exhausted and the crude oil vapor composition detected by the gas chromatograph is constant, the constant temperature distillation tube is connected with the constant temperature sealed cabinet, and a pressure pump is used to allow the crude oil vapor in the constant temperature distillation tube to 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 and keep the crude oil vapor adsorbed on the surface of the shale sample. Use a gas chromatograph to detect the components of the crude oil vapor in the constant temperature sealed cabinet and observe the crude oil vapor pressure in the constant temperature sealed cabinet. When the saturated vapor pressure in the constant temperature sealed cabinet does not change by more than 0.05KPa within 30 minutes, record the mass of the shale sample. and the pressure P2 of crude oil vapor, and the components of crude oil vapor in the constant temperature sealed cabinet are detected by gas chromatography; 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 component i in the crude oil sample i , the components of crude oil vapor in the constant temperature sealed cabinet are detected by gas chromatography until P i =P0, and record the mass of the shale sample when it is saturated with shale oil ; S12, taking out the shale sample from the constant temperature sealed cabinet, determining the mass of the shale sample saturated with crude oil, recorded as m2, and measuring the pore volume and pore size distribution of the shale sample saturated with crude oil; S13, calculating the adsorbed oil content of the shale sample by formula 1; Formula 1 in: Q is the adsorbed oil content of the shale sample, in mg / g; is the mass of the shale sample when saturated with shale oil, in g; is the mass of the shale sample without adsorbed oil, in g; S14, the pressure collected by the pressure sensor at different test pressure points corresponds to the pressure of the gas chromatograph analyzer, the corresponding pressure value when different components in the chromatographic column change is analyzed, and the adsorbed oil content of different components is calculated by formula 2; Formula 2 in: Q i is the adsorbed oil content of component i in the shale sample, in mg / g; is the mass of the shale sample when saturated with shale oil, in g; is the mass of adsorbed oil measured at the i-th pressure point in the shale sample, in g; is the mass of adsorbed oil measured at the i-1th pressure point in the shale sample, in g; S15. According to the Kelvin equation and the Hulsey equation, the minimum occurrence pore size lower limit of component i in the shale sample is obtained; Formula 3 in: is the minimum pore size lower limit of component i in the shale sample, in nm; is the saturated vapor pressure of component i 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 when the adsorbed oil in the shale sample is saturated with the adsorbed oil according to the pore volume of the shale sample before the experiment and the pore volume of the shale sample saturated with crude oil; Formula 4 in: S h is the oil saturation of the shale sample when the adsorbed oil is saturated, the unit is %; V t It is the pore volume of the pores not occupied by the adsorbed oil after the shale sample is saturated with crude oil, in ml / g; V1 is the pore volume measured after the shale sample is washed clean of oil, and the unit is ml / g.

[0021] The beneficial effects of the present invention are mainly manifested in the following aspects: 1. Compared with the prior art, the present invention can obtain the proportion of different components in crude oil in adsorbed oil by detecting the changes in gas chromatography data of crude oil vapor before and after adsorption, provide more accurate information on the proportion of adsorbed oil components, and thus ensure the measurement accuracy of adsorbed oil content data in pores of different pore sizes in shale.

[0022] 2. The present invention can evaporate liquid crude oil into crude oil vapor and allow the crude oil vapor to be 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 adsorption. The adsorption of different components of crude oil in the shale sample is then determined based on the change in the gas chromatography analysis results of the crude oil vapor before and after adsorption, thereby obtaining the component information of the adsorbed oil of different components in the shale.

[0023] 3. The vacuum device of the present invention can extract the air in the constant temperature sealed cabinet, the constant temperature distillation tube and the connecting pipeline before the experiment to prevent the air from interfering with the measurement of the adsorbed oil content and the adsorbed oil components, which is beneficial to improve the measurement accuracy.

[0024] 4. Compared with the Chinese patent document with publication number CN115701640A and publication date February 10, 2023, the present invention uses shale oil vapor formed by evaporation under a high vacuum environment to be adsorbed on the shale surface and isolated from the external environment, which 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 kerogen cracking in the shale, destroy 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.

[0025] 5. The present invention utilizes the capillary condensation phenomenon to obtain data on adsorbed oil content in pores of different pore sizes in shale and the lower limits of pore sizes for adsorbed oil storage of different components, providing more comprehensive information.

[0026] 6. The present invention obtains the oil saturation of shale adsorbed oil through the change of shale pore volume before and after the adsorption experiment. Multiple experimental data can be obtained by conducting one experiment, thereby improving the experimental efficiency.

[0027] 7. The present invention, by connecting to a gas chromatograph, can truly reflect the component characteristics of adsorbed crude oil in the pore spaces of different pore sizes in shale, thereby ensuring measurement accuracy.

[0028] 8. The present invention allows crude oil vapor to evaporate into gas under a high vacuum environment and then be adsorbed on the shale surface, thereby retaining the original component characteristics of the crude oil to the greatest extent and avoiding the influence of the loss of light components during crude oil distillation on the analysis of adsorbed oil components.

[0029] 9. The present invention can obtain the minimum storage pore size lower limit of shale oil of different components by designing different adsorption pressure points and analyzing the component changes of shale oil vapor of different components at the pressure points; the adsorbed oil content is analyzed by using the mass change of shale samples before and after adsorption to obtain the adsorbed oil content data in different pore sizes.

[0030] 10. The present invention can obtain component characteristic information of different components of adsorbed oil by analyzing the component types and mass fractions of crude oil before and after vapor adsorption using a gas chromatograph. DETAILED DESCRIPTION

[0031] Example 1 A device for measuring the adsorbed oil content and components in reservoir pores comprises a temperature sensor, a pressure sensor, a magnetic suspension balance, a gas chromatograph, a thermostatic sealed cabinet, a thermostatic distillation tube, a vacuum pump, a dryer and a pressure pump. The dryer is arranged between the thermostatic sealed cabinet and the thermostatic distillation tube, and is used to remove water vapor generated by heating crude oil. The magnetic suspension balance is used to detect the change in sample mass before and after the shale sample absorbs crude oil vapor under different relative pressures. The gas chromatograph is used to detect the shale oil vapor components in the thermostatic distillation tube and the thermostatic sealed cabinet at different temperatures. The thermostatic distillation tube is used to contain liquid crude oil and evaporate the liquid crude oil into gaseous state. The vacuum pump is used to extract air in the thermostatic sealed cabinet and the thermostatic distillation tube. The pressure pump is arranged on the connecting pipeline between the thermostatic sealed cabinet and the thermostatic distillation tube, and is used to increase the crude oil vapor pressure 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 crude oil vapor pressure in the thermostatic sealed cabinet.

[0032] This embodiment is the most basic implementation method. Compared with the existing technology, 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 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 pore sizes in shale.

[0033] Example 2 A device for measuring the adsorbed oil content and components in reservoir pores comprises a temperature sensor, a pressure sensor, a magnetic suspension balance, a gas chromatograph, a thermostatic sealed cabinet, a thermostatic distillation tube, a vacuum pump, a dryer and a pressure pump. The dryer is arranged between the thermostatic sealed cabinet and the thermostatic distillation tube, and is used to remove water vapor generated by heating crude oil. The magnetic suspension balance is used to detect the change in sample mass before and after the shale sample absorbs crude oil vapor under different relative pressures. The gas chromatograph is used to detect the shale oil vapor components in the thermostatic distillation tube and the thermostatic sealed cabinet at different temperatures. The thermostatic distillation tube is used to contain liquid crude oil and evaporate the liquid crude oil into gaseous state. The vacuum pump is used to extract air in the thermostatic sealed cabinet and the thermostatic distillation tube. The pressure pump is arranged on the connecting pipeline between the thermostatic sealed cabinet and the thermostatic distillation tube, and is used to increase the crude oil vapor pressure 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 crude oil vapor pressure in the thermostatic sealed cabinet.

[0034] Furthermore, the gas chromatograph includes a chromatographic column and a detector, and the detector is a flame ionization detector. The constant temperature sealed cabinet is provided with a port for loading shale samples. The constant temperature of the constant temperature sealed cabinet is -20-100°C. The pressure bearing capacity of the constant temperature sealed cabinet is 10MPa. The measuring range of the pressure sensor is -100KPa-10MPa, and the accuracy is 0.01Kpa. The constant temperature of the constant temperature distillation tube is -20-100°C. The capacity of the constant temperature distillation tube is 100ml, and the pressure bearing capacity is 5MPa. The accuracy of the pressure pump is 0.01KPa.

[0035] This embodiment is a preferred implementation method, which can evaporate liquid crude oil into crude oil vapor and make the crude oil vapor adsorb on the surface of the shale sample. The shale adsorbed oil content is analyzed by detecting the mass change of the shale sample before and after adsorption, and then the adsorption of different crude oil components in the shale sample is judged according to the change of the gas chromatography analysis results of the crude oil vapor before and after adsorption, and the component information of the adsorbed oil of different components in the shale is obtained.

[0036] Example 3 A method for measuring the content and components of adsorbed oil in reservoir pores comprises the following steps: S1. Select a shale sample from a shale oil reservoir, crush the shale sample into particles with a particle size of 100 μm, and weigh 10 g of the particle sample; S2, washing the shale sample with oil and measuring the pore volume and pore size distribution of the shale sample; S3, take 50 ml of crude oil sample and measure the saturated vapor pressure of the crude oil sample, recorded as P0; S4, take another 50 ml crude oil sample and measure the critical temperature of the crude oil sample, which is recorded as T0; S5. Take another 50 ml crude oil sample and put it into a constant temperature distillation tube. Set the constant temperature of the constant temperature distillation tube to T0, calibrate the magnetic suspension balance, and take 10 g of the shale sample after oil washing and place it 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 turn on the vacuum pumping device to evacuate the constant temperature sealed cabinet until the pressure in the constant temperature sealed cabinet is lower than -100KPa; S7. Measure the mass of shale samples without adsorbed oil by magnetic suspension balance ; S8, evacuating the constant temperature distillation tube by a vacuum pumping device to evaporate the crude oil in the constant temperature distillation tube at a critical temperature and low pressure, connecting a gas chromatograph to continuously detect the components of the crude oil vapor; S9. When the air in the constant temperature distillation tube is exhausted and the crude oil vapor composition detected by the gas chromatograph is constant, the constant temperature distillation tube is connected with the constant temperature sealed cabinet, and a pressure pump is used to allow the crude oil vapor in the constant temperature distillation tube to 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 and keep the crude oil vapor adsorbed on the surface of the shale sample. Use a gas chromatograph to detect the components of the crude oil vapor in the constant temperature sealed cabinet and observe the crude oil vapor pressure in the constant temperature sealed cabinet. When the saturated vapor pressure in the constant temperature sealed cabinet does not change by more than 0.05KPa within 30 minutes, record the mass of the shale sample. and the pressure P2 of crude oil vapor, and the components of crude oil vapor in the constant temperature sealed cabinet are detected by gas chromatography; 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 component i in the crude oil sample i , the components of crude oil vapor in the constant temperature sealed cabinet are detected by gas chromatography until P i =P0, and record the mass of the shale sample when it is saturated with shale oil QUOTE ; S12, taking out the shale sample from the constant temperature sealed cabinet, determining the mass of the shale sample saturated with crude oil, recorded as m2, and measuring the pore volume and pore size distribution of the shale sample saturated with crude oil; S13, calculating the adsorbed oil content of the shale sample by formula 1; Formula 1 in: Q is the adsorbed oil content of the shale sample, in mg / g; is the mass of the shale sample when saturated with shale oil, in g; is the mass of the shale sample without adsorbed oil, in g; S14, the pressure collected by the pressure sensor at different test pressure points corresponds to the pressure of the gas chromatograph analyzer, the corresponding pressure value when different components in the chromatographic column change is analyzed, and the adsorbed oil content of different components is calculated by formula 2; Formula 2 in: Q i is the adsorbed oil content of component i in the shale sample, in mg / g; is the mass of the shale sample when saturated with shale oil, in g; is the mass of adsorbed oil measured at the i-th pressure point in the shale sample, in g; is the mass of adsorbed oil measured at the i-1th pressure point in the shale sample, in g; S15. According to the Kelvin equation and the Hulsey equation, the minimum occurrence pore size lower limit of component i in the shale sample is obtained; Formula 3 in: is the minimum pore size lower limit of component i in the shale sample, in nm; is the saturated vapor pressure of component i 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 when the adsorbed oil in the shale sample is saturated with the adsorbed oil according to the pore volume of the shale sample before the experiment and the pore volume of the shale sample saturated with crude oil; Formula 4 in: S h is the oil saturation of the shale sample when the adsorbed oil is saturated, the unit is %; V t It is the pore volume of the pores not occupied by the adsorbed oil after the shale sample is saturated with crude oil, in ml / g; V1 is the pore volume measured after the shale sample is washed clean of oil, and the unit is ml / g.

[0037] This embodiment is another preferred implementation method. The vacuum device can extract the air in the constant temperature sealed cabinet, the constant temperature distillation tube and the connecting pipeline before the experiment to prevent the air from interfering with the measurement of the adsorbed oil content and the adsorbed oil components, which is beneficial to improving the measurement accuracy.

[0038] Compared with the Chinese patent document with publication number CN115701640A and publication date February 10, 2023, shale oil vapor formed by evaporation under a high vacuum environment is adsorbed on the shale surface and 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 that causes kerogen in the shale to crack, destroy 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.

[0039] Example 4 A method for measuring the content and components of adsorbed oil in reservoir pores comprises the following steps: S1. Select shale samples from shale oil reservoirs, crush the shale samples into particles with a particle size of 150 μm, and weigh 20 g of the particle samples; S2. Wash the shale samples with oil and measure the pore volume and pore size distribution of the shale samples; S3. Take 100 ml of crude oil sample and measure the saturated vapor pressure of the crude oil sample, recorded as P0; S4. Take another 100 ml of crude oil sample and measure the critical temperature of the crude oil sample, recorded as T0; S5. Take another 100 ml of crude oil sample and put it into a constant temperature distillation tube, set the constant temperature of the constant temperature distillation tube to T0, calibrate the magnetic suspension balance, take 20 g of the shale sample after oil washing and place it 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 at the same time turn on the vacuum device to evacuate the constant temperature sealed cabinet until the pressure in the constant temperature sealed cabinet is lower than -100 KPa; S7. Measure the mass of the shale sample without adsorbed oil by using a magnetic suspension balance ; S8. Use a vacuum pump to evacuate the constant temperature distillation tube to evaporate the crude oil in the constant temperature distillation tube at a critical temperature and low pressure, connect the gas chromatograph, 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 are fixed, connect the constant temperature distillation tube with the constant temperature sealed cabinet, use a pressure pump to allow the crude oil vapor in the constant temperature distillation tube to 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 surface of the shale sample, detect the components of the crude oil vapor in the constant temperature sealed cabinet by the gas chromatograph, and observe the crude oil vapor pressure in the constant temperature sealed cabinet. When the saturated vapor pressure in the constant temperature sealed cabinet does not change by more than 0.05 KPa within 30 minutes, record the mass of the shale sample. and the pressure P2 of crude oil vapor, and the components of crude oil vapor in the constant temperature sealed cabinet are detected by gas chromatography; S11, the crude oil vapor pressure in the constant temperature sealed cabinet is continued to be increased by the booster pump, and step S10 is repeated to record the mass of the shale sample at each set pressure point and the saturated vapor pressure P of component i in the crude oil sample i , the components of crude oil vapor in the constant temperature sealed cabinet are detected by gas chromatography until P i =P0, and record the mass of the shale sample when it is saturated with shale oil ; S12, take out the shale sample from the constant temperature sealed cabinet, measure the mass of the shale sample saturated with crude oil, record it as m2, and measure the pore volume and pore size distribution of the shale sample saturated with crude oil; S13, calculate the adsorbed oil content of the shale sample by formula 1; Formula 1 in: Q is the adsorbed oil content of the shale sample, in mg / g; is the mass of the shale sample when saturated with shale oil, in g; is the mass of the shale sample without adsorbed oil, in g; S14, the pressure collected by the pressure sensor at different test pressure points corresponds to the pressure of the gas chromatograph analyzer, the corresponding pressure value when different components in the chromatographic column change is analyzed, and the adsorbed oil content of different components is calculated by formula 2; Formula 2 in: Q i is the adsorbed oil content of component i in the shale sample, in mg / g; is the mass of the shale sample when saturated with shale oil, in g; is the mass of adsorbed oil measured at the i-th pressure point in the shale sample, in g; is the mass of adsorbed oil measured at the i-1th pressure point in the shale sample, in g; S15. According to the Kelvin equation and the Hulsey equation, the minimum occurrence pore size lower limit of component i in the shale sample is obtained; Formula 3 in: is the minimum pore size lower limit of component i in the shale sample, in nm; is the saturated vapor pressure of component i 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 when the adsorbed oil in the shale sample is saturated with the adsorbed oil according to the pore volume of the shale sample before the experiment and the pore volume of the shale sample saturated with crude oil; Formula 4 in: S h is the oil saturation of the shale sample when the adsorbed oil is saturated, the unit is %; V t It is the pore volume of the pores not occupied by the adsorbed oil after the shale sample is saturated with crude oil, in ml / g; V1 is the pore volume measured after the shale sample is washed clean of oil, and the unit is ml / g.

[0040] This embodiment is the best implementation method. By using the capillary condensation phenomenon, the adsorbed oil content data in pores of different pore sizes in shale and the lower limit of the pore size of adsorbed oil of different components can be obtained, providing more comprehensive information.

[0041] The oil saturation of shale adsorbed oil is obtained by the change of shale pore volume before and after the adsorption experiment. Multiple experimental data can be obtained by conducting one experiment, which improves the experimental efficiency.

[0042] By connecting to a gas chromatograph, the component characteristics of the adsorbed crude oil in the pore spaces of different pore sizes in shale can be truly reflected, ensuring measurement accuracy.

[0043] The crude oil vapor is evaporated into gas under high vacuum environment and then adsorbed on the shale surface, which retains the original component characteristics of the crude oil to the greatest extent and avoids the influence of the loss of light components during crude oil distillation on the analysis of adsorbed oil components.

[0044] By designing different adsorption pressure points and analyzing the composition changes of shale oil vapor with different components at the pressure points, the minimum storage pore size lower limit of shale oil with different components can be obtained; by analyzing the adsorbed oil content by using the mass change of shale samples before and after adsorption, the adsorbed oil content data in different pore sizes can be obtained.

[0045] By analyzing the component types and mass fractions of crude oil before and after vapor adsorption using a gas chromatograph, the component characteristic information of the adsorbed oil of different components can be obtained.

[0046] The calculation principle of the adsorbed oil content of different components of the present invention is as follows: The pressure collected by the pressure sensor at different test pressure points is matched with the gas chromatograph at the pressure, and the corresponding pressure values ​​when different components in the chromatographic column change are analyzed. Since the saturated vapor pressures of different components in the crude oil sample are different, at the critical temperature, the component with low saturated vapor pressure will first liquefy and adsorb 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; Formula 2 in: Q i is the adsorbed oil content of component i in the shale sample, in mg / g; is the mass of the shale sample when saturated with shale oil, in g; is the mass of adsorbed oil measured at the i-th pressure point in the shale sample, in g; is the mass of adsorbed oil measured at the i-1th pressure point in the shale sample, in g.

[0047] The calculation principle of the minimum occurrence pore size lower limit of component i in the shale sample of the present invention is as follows: At the critical temperature of crude oil sample, the adsorption of crude oil sample vapor on the shale surface increases with As / P0 increases, capillary condensation occurs in shale pores with different pore sizes, that is, the crude oil sample vapor condenses into liquid crude oil in the pores and forms a concave liquid surface, causing capillary condensation. It is related to the capillary pore size, so according to the Kelvin equation and the Hulsey equation, the minimum occurrence pore size lower limit of component i in the shale sample can be obtained; Formula 3 in: is the minimum pore size lower limit of component i in the shale sample, in nm; is the saturated vapor pressure of component i in the crude oil sample, in MPa; P0 is the saturated vapor pressure of the crude oil sample, in MPa.

Claims

1. A device for measuring the content and composition of adsorbed oil in reservoir pores, comprising a temperature sensor and a pressure sensor, characterized in that: It also includes a magnetic suspension balance, a gas chromatograph, a constant temperature sealed cabinet, a constant temperature distillation tube, a vacuum pump, a dryer and a pressure pump. The dryer is arranged between the constant temperature sealed cabinet and the constant temperature distillation tube, and is used to remove water vapor generated by heating crude oil. The magnetic suspension balance is used to detect changes in sample mass before and after shale samples absorb crude oil vapor at different relative pressures. The gas chromatograph is used to detect 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 contain liquid crude oil and evaporate the liquid crude oil into gas. The vacuum pump is used to extract air from 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. The pressure pump is used to increase the crude oil vapor pressure 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. The pressure sensor is used to measure the crude oil vapor pressure in the constant temperature sealed cabinet.

2. The device for measuring the content and composition of adsorbed oil in reservoir pores according to claim 1, characterized in that: The gas chromatograph comprises a chromatographic column and a detector, wherein the detector is a flame ionization detector or a flame thermal ionization detector.

3. The device for measuring the content and composition of adsorbed oil in reservoir pores according to claim 1, characterized in that: The constant temperature sealed cabinet is provided with a port for loading shale samples.

4. The device for measuring the content and composition of adsorbed oil in reservoir pores according to claim 1, characterized in that: The constant temperature of the constant temperature sealing cabinet is -20-100°C.

5. The device for measuring the content and composition of adsorbed oil in reservoir pores according to claim 1, characterized in that: The constant temperature sealed cabinet has a pressure bearing capacity of 10 MPa.

6. The device for measuring the content and composition of adsorbed oil in reservoir pores according to claim 1, characterized in that: The measuring range of the pressure sensor is -100KPa-10MPa, and the accuracy is 0.01Kpa.

7. The device for measuring the content and composition of adsorbed oil in reservoir pores according to claim 1, characterized in that: The constant temperature of the constant temperature distillation tube is -20-100°C.

8. The device for measuring the content and composition of adsorbed oil in reservoir pores according to claim 1, characterized in that: The constant temperature distillation tube has a capacity of 100 ml and a pressure resistance of 5 MPa.

9. The device for measuring the content and composition of adsorbed oil in reservoir pores according to claim 1, characterized in that: The accuracy of the pressure pump is 0.01 KPa.

10. A method for measuring the content and composition of adsorbed oil in reservoir pores, characterized in that: The measurement is performed using the device, comprising the following steps: S1. Select shale samples from shale oil reservoirs, crush the shale samples into particles with a particle size of 100-150 μm, and weigh 10-20 g of the particle samples; S2, washing the shale sample with oil and measuring the pore volume and pore size distribution of the shale sample; S3, take 50-100 ml of crude oil sample and measure the saturated vapor pressure of the crude oil sample, recorded as P0; S4, take another 50-100 ml crude oil sample and measure the critical temperature of the crude oil sample, which is recorded as T0; S5. Take another 50-100 ml crude oil sample and put it into a constant temperature distillation tube. Set the constant temperature of the constant temperature distillation tube to T0, calibrate the magnetic suspension balance, and take 10-20 g of the shale sample after oil washing and place it 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 turn on the vacuum pumping device to evacuate the constant temperature sealed cabinet until the pressure in the constant temperature sealed cabinet is lower than -100KPa; S7. measuring the mass of the shale sample without adsorbed oil by means of a magnetic suspension balance; S8, evacuating the constant temperature distillation tube by a vacuum pumping device to evaporate the crude oil in the constant temperature distillation tube at a critical temperature and low pressure, connecting a gas chromatograph to continuously detect the components of the crude oil vapor; S9. When the air in the constant temperature distillation tube is exhausted and the crude oil vapor composition detected by the gas chromatograph is constant, the constant temperature distillation tube is connected with the constant temperature sealed cabinet, and a pressure pump is used to allow the crude oil vapor in the constant temperature distillation tube to 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 and keep the crude oil vapor adsorbed on the surface of the shale sample. Use a gas chromatograph to detect the components of the crude oil vapor in the constant temperature sealed cabinet and observe the crude oil vapor pressure in the constant temperature sealed cabinet. When the saturated vapor pressure in the constant temperature sealed cabinet does not change by more than 0.05KPa within 30 minutes, record the mass of the shale sample. and the pressure P2 of crude oil vapor, and the components of crude oil vapor in the constant temperature sealed cabinet are detected by gas chromatography; 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 component i in the crude oil sample i , the components of crude oil vapor in the constant temperature sealed cabinet are detected by gas chromatography until P i =P0, and record the mass of the shale sample when it is saturated with shale oil ; S12, taking out the shale sample from the constant temperature sealed cabinet, determining the mass of the shale sample saturated with crude oil, recorded as m2, and measuring the pore volume and pore size distribution of the shale sample saturated with crude oil; S13, calculating the adsorbed oil content of the shale sample by formula 1; Formula 1 in: Q is the adsorbed oil content of the shale sample, in mg / g; is the mass of the shale sample when saturated with shale oil, in g; is the mass of the shale sample without adsorbed oil, in g; S14, the pressure collected by the pressure sensor at different test pressure points corresponds to the pressure of the gas chromatograph analyzer, the corresponding pressure value when different components in the chromatographic column change is analyzed, and the adsorbed oil content of different components is calculated by formula 2; Formula 2 in: Q i is the adsorbed oil content of component i in the shale sample, in mg / g; is the mass of the shale sample when saturated with shale oil, in g; is the mass of adsorbed oil measured at the i-th pressure point in the shale sample, in g; is the mass of adsorbed oil measured at the i-1th pressure point in the shale sample, in g; S15. According to the Kelvin equation and the Hulsey equation, the minimum occurrence pore size lower limit of component i in the shale sample is obtained; Formula 3 in: is the minimum pore size lower limit of component i in the shale sample, in nm; is the saturated vapor pressure of component i 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 when the adsorbed oil in the shale sample is saturated with the adsorbed oil according to the pore volume of the shale sample before the experiment and the pore volume of the shale sample saturated with crude oil; Formula 4 in: S h is the oil saturation of the shale sample when the adsorbed oil is saturated, the unit is %; V t It is the pore volume of the pores not occupied by the adsorbed oil after the shale sample is saturated with crude oil, in ml / g; V1 is the pore volume measured after the shale sample is washed clean of oil, and the unit is ml / g.