A test method for the adsorption and desorption capacity of condensate gas

Abstract

The present invention discloses a method for testing the adsorption and desorption capabilities of condensate gas, which includes: after screening reservoir rock cuttings and loading them into a sample cylinder, first injecting methane to make the gas pressure in the sample cylinder higher than the dew point pressure of the condensate gas, then injecting a mixed gas into a reference cylinder to reach a set pressure. After connecting the sample cylinder and the reference cylinder to configure the condensate gas, then injecting the condensate gas and increasing the pressure from a set pressure gradient to the reservoir pressure, measuring the adsorption amount of the condensate gas by the rock at different pressure points above the dew point pressure, and then decreasing the pressure in a gradient to measure the desorption amount of the condensate gas by the rock at different pressure points. Based on the experimental results of the constant mass expansion of the condensate gas, the measurement error of the gas desorption amount caused by the volume of retrograde condensate oil is eliminated, and the adsorption / desorption capabilities of the rock sample for the condensate gas are evaluated. Through the above solution, the present invention can accurately measure the adsorption / desorption amount of the condensate gas, which is helpful for the reserve calculation and efficient development of condensate gas reservoirs.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and gas engineering, and particularly to an evaluation method for the volume change of reservoir gas adsorption / desorption caused by pressure change during engineering operations such as reservoir development and stimulation, specifically a test method for evaluating the adsorption and desorption capacities of condensate gas. Background Art

[0002] During the exploration and development of oil reservoirs, as gas production leads to a decrease in reservoir pressure, the phase state of condensate gas will also change, resulting in condensate oil and the occurrence of retrograde condensation. Condensate gas is a mixture of various hydrocarbons. Due to the occurrence of retrograde condensation, the conventional volumetric method and gravimetric method cannot measure the adsorption / desorption capacity of condensate gas. These methods fail to effectively obtain the adsorption / desorption volume of condensate gas at different pressures, making it difficult to provide a theoretical basis for gas injection development and prevention of retrograde condensation damage, and restricting the accuracy of reserve evaluation and economic development of tight rock gas reservoirs.

[0003] The current test methods for the adsorption amount of condensate gas all use gases that do not undergo phase changes to replace condensate gas for measurement, without considering the competitive adsorption of gases with different components and the influence of condensate oil production on the desorption capacity of condensate gas, and cannot measure the adsorption / desorption amount of real condensate gas. In order to provide a basis for measuring the adsorption and desorption amounts of condensate gas in the case of retrograde condensation in condensate gas reservoirs, evaluating the reserves of condensate gas, and optimizing the development plan, the present invention makes up for the deficiencies of the volumetric method and the gravimetric method, eliminates the errors caused by the production of condensate oil, and establishes an evaluation method capable of measuring the adsorption and desorption capacities of condensate gas. Summary of the Invention

[0004] Aiming at the above problems, the purpose of the present invention is to provide a test method for the adsorption and desorption capacities of condensate gas. The technical solution adopted by the present invention is as follows:

[0005] A test method for the adsorption and desorption capacity of condensate gas, which uses a condensate gas adsorption and desorption capacity test device to conduct a test. The characteristics are as follows: The condensate gas adsorption and desorption capacity test device includes a booster pump, a methane gas cylinder, a first helium gas cylinder, a mixed gas cylinder, a condensate gas cylinder, and a second helium gas cylinder connected to the booster pump. A first valve is connected to the outlet section of the methane gas cylinder, a reference cylinder A is connected to the first valve, a first pressure sensor is set on the reference cylinder A, a second valve is connected to the outlet of the reference cylinder A, a third valve is connected to the outlet of the mixed gas cylinder, a reference cylinder B is connected to the third valve, a second pressure sensor is set on the reference cylinder B, a fourth valve is connected to the outlet of the reference cylinder B, a fifth valve is connected to the outlet section of the condensate gas cylinder, a reference cylinder C is connected to the fifth valve, a third pressure sensor is set on the reference cylinder C, a sixth valve is connected to the outlet of the reference cylinder C, a sample cylinder is connected to the outlets of the second valve, the fourth valve, and the sixth valve, a temperature sensor is set on the sample cylinder, a seventh valve is connected to the outlet of the sample cylinder, a fourth pressure sensor is connected to the seventh valve, a vacuum pump is connected to the outlet of the seventh valve, a backpressure valve is connected to the outlet of the sample cylinder, a gas collection device is connected to the outlet of the backpressure valve, a fifth pressure sensor is set on the gas collection device, and a computer control system is respectively connected to the first pressure sensor, the second pressure sensor, the third pressure sensor, the fourth pressure sensor, the fifth pressure sensor, and the temperature sensor. The sample cylinder contains the rock cuttings sample to be tested, and the reference cylinder A, the reference cylinder B, the reference cylinder C, and the sample cylinder are arranged in a constant temperature bath;

[0006] The test method for the adsorption and desorption capacity of condensate gas includes the following steps:

[0007] S1. After washing the downhole rock sample with oil, washing with salt, and drying, use the sieving method to screen out rock fragments within the particle size range of 60 - 80 mesh;

[0008] S2. Keep all valves closed, and load the rock fragments into the sample cylinder; Open the second valve, the fourth valve, the sixth valve, and the seventh valve to connect the reference cylinder A, the reference cylinder B, the reference cylinder C, and the sample cylinder, and evacuate the system through the vacuum pump; After the evacuation is completed, close the second valve, the sixth valve, and the seventh valve, open the first valve, use the first helium gas cylinder to introduce helium gas into the system, adjust the pressure of the reference cylinder A to the set pressure through the booster pump, and collect the pressure value after the air pressure in the reference cylinder A is stable; Close the first valve, open the second valve, connect the reference cylinder A, the reference cylinder B, and the sample cylinder, and after the pressure is balanced, collect the final pressure after balance to calibrate the free space volume of the first system V 1; Then evacuate the system and close all valves; Open the fifth valve, introduce helium into the system through the second helium cylinder, adjust the pressure of the reference cylinder C to the set pressure through the booster pump, and collect the pressure value after the air pressure in the reference cylinder C stabilizes; Connect the reference cylinder C and the sample, and after the pressure is balanced, collect the final pressure after balance, and then the free space volume of the second system can be calculated. V 2 Place the reference cylinder A, reference cylinder B, reference cylinder C and the sample cylinder in a constant temperature bath to simulate the reservoir temperature of the rock sample.

[0009] S3. Open the first valve and close the second valve. Use the methane gas cylinder to introduce methane into the reference cylinder A until the set pressure is P A , then close the first valve, open the second valve, connect the reference cylinder A and the sample cylinder, and wait for the reading of the fourth pressure sensor to stabilize; Open the third valve, introduce the mixed gas into the reference cylinder B through the mixed gas cylinder until the set pressure P B ; Close the third valve, open the fourth valve, connect the reference cylinder B with the reference cylinder A and the sample cylinder, and after the pressure of the fourth pressure sensor in the sample cylinder stabilizes for 12 h, record the time, pressure P x and temperature to complete the adsorption amount test of the initial pressure point P x of the sample.

[0010] Initial point P x The adsorption amount of the condensate gas is calculated by the following formula:

[0011]

[0012] When the pressure is increased in gradient, the adsorption amount at the pressure point P i is calculated by the following formula:

[0013]

[0014] V x is the adsorption amount of the condensate gas, cm 3 / g; V A , V B , V C and V are the volumes of the reference cylinder A, reference cylinder B, reference cylinder C and the sample cylinder respectively, cm 3 ; P A and P BThey are the set pressures of reference cylinder A and reference cylinder B, in MPa; V 1 and V 2 are the measured free space volumes of the first and second systems, in cm 3 ;

[0015] S4. Close the second valve and the fourth valve, open the fifth valve, pump condensate gas into reference cylinder C through the condensate gas cylinder, and record the pressure of reference cylinder C as P c ; Close the fifth valve and open the sixth valve to connect reference cylinder C with the sample cylinder, so that the pressure in the sample cylinder reaches the pressure point to be measured; Starting from P x as the initial point, increase the pressure in gradients. After stabilizing for 12 h at each pressure point, record the time, temperature, and pressure P i , and test the condensate gas adsorption amount of the sample at different pressure points;

[0016] S5. When the pressure point rises to the reservoir pressure, start to decrease the pressure in gradients and measure the condensate gas desorption amount at different pressure points; Keep all valves closed, then open the sixth valve to connect reference cylinder C with the sample cylinder, control the pressure in the sample cylinder by adjusting the back pressure of the back pressure valve, and collect the gas volume at the outlet end of the back pressure valve; During the process of decreasing the pressure from the reservoir pressure to the atmospheric pressure, at least 10 pressure points are successively set as the back pressure. After each test pressure stabilizes for 12 h, record the time, pressure P 1 and temperature T ;

[0017] The pressure points in the desorption stage P 1 The condensate gas desorption amount is calculated by the following formula:

[0018]

[0019] V JX is the amount of desorbed gas, in cm 3 ; P max is the end pressure of the adsorption experiment, in MPa; V max is the end pressure of the adsorption experiment P max The adsorption amount at 3 is in cm P out is the pressure of the gas collection device, in MPa; V out is the volume of the gas collection device, in cm 3; N The percentage of condensate volume measured in the constant mass expansion experiment, %; P 1 The pressure at each measurement point, MPa.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] (1) The present invention is applicable to condensate gas reservoirs with multi-component gases in some reservoirs, solving the problems that only the adsorption / desorption capacity of a single gas in the rock can be tested separately and the competitive adsorption between multi-component gases is not considered, thus making it impossible to truly measure the adsorption / desorption amount of condensate gas.

[0022] (2) The present invention can be used to measure the gas adsorption / desorption capacity of tight rocks under the condition of retrograde condensation, solving the problem that the phase change generates condensate oil, resulting in the inability to measure the adsorption / desorption amount of the rock. Description of the Drawings

[0023] Figure 1 It is a schematic structural diagram of the present invention.

[0024] In the above drawings, the component names corresponding to the reference numerals are as follows:

[0025] 1. Booster pump; 2. Methane gas cylinder; 3. First valve; 4. First pressure sensor; 5. Second valve; 6. Reference cylinder A; 7. Mixed gas cylinder; 8. Third valve; 9. Second pressure sensor; 10. Fourth valve; 11. Reference cylinder B; 12. Condensate gas cylinder; 13. Fifth valve; 14. Third pressure sensor; 15. Reference cylinder C; 16. Sixth valve; 17. Temperature sensor; 18. Sample cylinder; 19. Seventh valve; 20. Fourth pressure sensor; 21. Back pressure valve; 22. Vacuum pump; 23. Computer control system; 24. Constant temperature bath; 25. First helium gas cylinder; 26. Second helium gas cylinder; 27. Gas collection device; 28. Fifth pressure sensor. Detailed Embodiments

[0026] To make the objectives, technical solutions and advantages of the present application clearer, the present invention will be further described below with reference to the drawings and embodiments. The embodiments of the present invention include but are not limited to the following embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of the present application.

[0027] In this embodiment, the term "and / or" only describes the associated relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent three situations: A exists alone, A and B exist simultaneously, and B exists alone.

[0028] In the description of the specification and claims of this embodiment, terms such as "first" and "second" are used to distinguish different objects, rather than to describe a specific order of the objects. For example, the first target object and the second target object are used to distinguish different target objects, rather than to describe a specific order of the target objects.

[0029] In the embodiments of this application, words such as "exemplary" or "for example" are used to indicate examples, illustrations, or explanations. Any embodiment or design solution described as "exemplary" or "for example" in the embodiments of this application should not be construed as being more preferred or having more advantages than other embodiments or design solutions. Rather, the use of words such as "exemplary" or "for example" is intended to present relevant concepts in a specific manner.

[0030] In the description of the embodiments of this application, unless otherwise specified, the meaning of "a plurality of" refers to two or more. For example, a plurality of processing units refers to two or more processing units; a plurality of systems refers to two or more systems.

[0031] As Figure 1 shown, this embodiment provides a device for testing the adsorption and desorption capabilities of condensate gas. Under reservoir temperature and different pressure conditions, and considering the influence of condensate oil generated by phase change on the desorption behavior of condensate gas, the adsorption and desorption capabilities of condensate gas are determined through an indoor experimental device and method.

[0032] In this embodiment, a method for testing the adsorption and desorption capabilities of condensate gas includes the following steps:

[0033] Step S1: Use the gas-bearing cuttings of a certain Jurassic condensate gas field in the Sichuan Basin as the experimental sample. According to the core cleaning method specified in the Petroleum and Natural Gas Industry Standard of the People's Republic of China "SY / T 5336-2006 Core Analysis Method", thoroughly wash the salt and oil from the cutting sample. After drying the sample, screen out about 100 g of cuttings with a 60-80 mesh sieve.

[0034] Step S2: Keep all valves closed and load the rock fragments into the sample cylinder; open the second valve, the fourth valve, the sixth valve, and the seventh valve to connect the reference cylinder A, the reference cylinder B, the reference cylinder C, and the sample cylinder. Evacuate the system with a vacuum pump; after evacuation, close the second valve, the sixth valve, and the seventh valve, open the first valve, and use the first helium cylinder to introduce helium into the system. Adjust the pressure in the reference cylinder A to the set pressure through a booster pump. After the air pressure in the reference cylinder A stabilizes, collect this pressure value; close the first valve, open the second valve, connect the reference cylinder A, the reference cylinder B, and the sample cylinder, and after pressure equilibrium, collect the final pressure after equilibrium to calibrate the free space volume of the first system. V 1; Then evacuate the system and close all valves; Open the fifth valve, introduce helium into the system through the second helium cylinder, adjust the pressure of the reference cylinder C to the set pressure through the booster pump, and collect the pressure value after the air pressure in the reference cylinder C stabilizes. Connect the reference cylinder C and the sample, and after the pressure is balanced, collect the final pressure after balance, and then the free space volume of the second system can be calculated. V 2 ; Place the reference cylinder A, reference cylinder B, reference cylinder C and the sample cylinder in the constant temperature bath to simulate the reservoir temperature of the rock sample.

[0035] Step S3: Open the first valve and close the second valve. Use the methane gas cylinder to introduce methane into the reference cylinder A until the set pressure is P A , then close the first valve, open the second valve, connect the reference cylinder A and the sample cylinder, and wait for the reading of the fourth pressure sensor to stabilize; Open the third valve, introduce the mixed gas into the reference cylinder B through the mixed gas cylinder until the set pressure P B ; Close the third valve, open the fourth valve, connect the reference cylinder B with the reference cylinder A and the sample cylinder, and after the pressure of the fourth pressure sensor in the sample cylinder stabilizes for 12 hours, record the time, pressure P x and temperature to complete the adsorption amount test of the initial pressure point P x sample;

[0036] Initial point P x The adsorption amount of the condensate gas is calculated by the following formula:

[0037]

[0038] When the pressure is increased in gradients, the adsorption amount at the pressure point P i is calculated by the following formula:

[0039]

[0040] V x is the adsorption amount of the condensate gas, cm 3 / g; V A , V B , V C and V are the volumes of the reference cylinder A, reference cylinder B, reference cylinder C and the sample cylinder respectively, cm 3 ; P A and P Bare the set pressures of reference cylinder A and reference cylinder B, in MPa; V 1 and V 2 are the measured free space volumes of the first and second systems, in cm 3 .

[0041] Step S4: Close the second valve and the fourth valve, open the fifth valve, pump condensate gas into reference cylinder C through the condensate gas cylinder, and record the pressure of reference cylinder C as P c ; Close the fifth valve, open the sixth valve, connect reference cylinder C to the sample cylinder so that the pressure in the sample cylinder reaches the pressure point to be measured; Starting from P x as the initial point, increase the pressure in a gradient manner. After stabilizing for 12 h at each pressure point, record the time, temperature, and pressure P i , and measure the condensate gas adsorption amount of the sample at different pressure points.

[0042] Step S5: When the pressure point rises to the reservoir pressure, start to decrease the pressure in a gradient manner and measure the condensate gas desorption amount at different pressure points; Keep all valves closed, then open the sixth valve to connect reference cylinder C to the sample cylinder. Control the pressure in the sample cylinder by adjusting the back pressure of the back pressure valve, and collect the gas volume at the outlet end of the back pressure valve; At least 10 pressure points during the period of decreasing the pressure from the reservoir pressure to the atmospheric pressure are successively set as the back pressure. After each test pressure stabilizes for 12 h, record the time, pressure P 1 and temperature T ;

[0043] The pressure points in the desorption stage P 1 The condensate gas desorption amount is calculated by the following formula:

[0044]

[0045] V JX is the amount of desorbed gas, in cm 3 ; P max is the end pressure of the adsorption experiment, in MPa; V max is the end pressure of the adsorption experiment P max The adsorption amount at 3 is in cm P out is the pressure of the gas collection device, in MPa; V out is the volume of the gas collection device, in cm3 ; N is the percentage of condensate volume measured by the constant mass expansion experiment, %; P 1 is the pressure at each measurement point, MPa.

[0046] The experimental results show that at P X = 40 MPa, the adsorption amount of cuttings to condensate gas is 5.0935 cc / g; during the retrograde condensation process, P Jx = 25 MPa, through the constant mass expansion experiment, it can be known that the percentage of condensate liquid volume is 9.48% at this time; the desorption amount V JX = 0.1053 cc / g is obtained by formula calculation.

[0047] As mentioned above, it is not a restriction on the present invention in any form. Although the present invention has been disclosed through the above embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications to equivalent embodiments with equivalent changes within the scope of the technical solution of the present invention by using the disclosed technical content. However, as long as it does not depart from the content of the technical solution of the present invention, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A method for testing the adsorption and desorption capacity of condensate gas, which uses a condensate gas adsorption and desorption capacity testing device to perform a test experiment, characterized in that: The condensate gas adsorption and desorption test device comprises a booster pump (1), a methane gas cylinder (2) connected to the booster pump, a first helium gas cylinder (25), a mixed gas cylinder (7), a condensate gas cylinder (12), a second helium gas cylinder (26), a first valve (3) connected to the outlet section of the methane gas cylinder (2), a reference cylinder A (6) connected to the first valve, a first pressure sensor (4) arranged on the reference cylinder A (6), a second valve (5) connected to the outlet of the reference cylinder A (6), and a pressure sensor (6) disposed on the reference cylinder A (6). a third valve (8) connected to the outlet, a reference cylinder B (11) connected to the third valve, a second pressure sensor (9) arranged on the reference cylinder B (11), a fourth valve (10) connected to the outlet of the reference cylinder B (11), a fifth valve (13) connected to the outlet section of the condensate gas bottle (12), a reference cylinder C (15) connected to the fifth valve, a third pressure sensor (14) arranged on the reference cylinder C (15), a sixth valve (16) connected to the outlet of the reference cylinder C (15), and a (5), a sample cylinder (18) connected to the outlets of the fourth valve (10) and the sixth valve (16), a temperature sensor (17) arranged on the sample cylinder (18), a seventh valve (19) connected to the outlet of the sample cylinder (18), a fourth pressure sensor (20) connected to the seventh valve (19), a vacuum pump (22) connected to the outlet of the seventh valve (19), a back pressure valve (21) connected to the outlet of the sample cylinder (18), a gas collecting device (27) connected to the outlet of the back pressure valve, a fifth pressure sensor (28) arranged on the gas collecting device (27), and a computer control system respectively connected to the first pressure sensor (4), the second pressure sensor (9), the third pressure sensor (14), the fourth pressure sensor (20), the fifth pressure sensor (28) and the temperature sensor (17), wherein the sample cylinder (18) is placed with a rock cutting sample to be tested, and the reference cylinder A (6), the reference cylinder B (11), the reference cylinder C (15) and the sample cylinder (18) are arranged in a constant temperature pool (24); The method for testing the adsorption and desorption capacity of condensate gas comprises the following steps: S1. After washing the oil and salt from the downhole rock samples and drying them, the rock samples with a particle size range of 60-80 mesh are screened out by sieving method; S2, keep all valves closed, load the rock sample into the sample cylinder (18); open the second valve (5), the fourth valve (10), the sixth valve (16) and the seventh valve (19), connect the reference cylinder A (6), the reference cylinder B (11), the reference cylinder C (15) and the sample cylinder (18), and evacuate the system with the vacuum pump (22); after the evacuation is completed, close the second valve (5), the sixth valve (16) and the seventh valve (19), open the first valve (3), use the first helium bottle (25) to introduce helium into the system, adjust the pressure of the reference cylinder A (6) to the set pressure through the booster pump (1), and collect the pressure value after the air pressure in the reference cylinder A (6) is stabilized; close the first valve (3), open the second valve (5), connect the reference cylinder A (6) ), reference cylinder B (11) and sample cylinder (18), after the pressure is balanced, collect the final pressure after the balance, and calibrate the free space volume V1 of the first system; then evacuate the system and close all valves; open the fifth valve (13), introduce helium into the system through the second helium bottle (26), adjust the pressure of the reference cylinder C (15) to the set pressure through the booster pump (1), and collect the pressure value after the air pressure in the reference cylinder C (15) is stabilized; connect the reference cylinder C (15) and the sample cylinder (18), after the pressure is balanced, collect the final pressure after the balance, and calculate the free space volume V2 of the second system; place the reference cylinder A (6), reference cylinder B (11), reference cylinder C (15) and sample cylinder (18) in a constant temperature pool to simulate the rock sample reservoir temperature; S3, open the first valve (3), close the second valve (5), use the methane gas cylinder (2) to pass methane into the reference cylinder A (6) until the set pressure is P A Then close the first valve (3), open the second valve (5), connect the reference cylinder A (6) and the sample cylinder (18), wait for the fourth pressure sensor (20) to indicate a stable reading; open the third valve (8), and introduce the mixed gas into the reference cylinder B (11) through the mixed gas cylinder (7) until the set pressure P B Close the third valve (8), open the fourth valve (10), connect the reference cylinder B (11) with the reference cylinder A (6) and the sample cylinder (18), and wait for the pressure of the fourth pressure sensor (20) of the sample cylinder to stabilize for 12 hours, and record the time and pressure P x and temperature, complete the initial pressure point P x Adsorption capacity test of samples; S4. Close the second valve (5) and the fourth valve (10), open the fifth valve (13), pump condensate gas into the reference cylinder C (15) through the condensate gas bottle (12), and record the pressure of the reference cylinder C (15) as P c Close the fifth valve (13), open the sixth valve (16), connect the reference cylinder C (15) and the sample cylinder (18), so that the pressure in the sample cylinder (18) reaches the pressure point to be measured; P x The pressure was gradually increased from the initial point. After stabilization for 12 hours at each pressure point, the time, temperature and pressure P were recorded. i , the condensate gas adsorption capacity of the test sample at different pressure points; S5. When the pressure point rises to the reservoir pressure, start to reduce the pressure gradually and measure the desorption amount of condensate gas at different pressure points; keep all valves closed, then open the sixth valve (16), connect the reference cylinder C (15) and the sample cylinder (18), control the pressure in the sample cylinder by adjusting the back pressure of the back pressure valve (21), and collect the gas volume at the outlet of the back pressure valve; set at least 10 pressure points during the period from the reservoir pressure gradient to the atmospheric pressure as the back pressure, and record the time, pressure P1 and temperature T after each test pressure is stable for 12 hours.

2. The method for testing the adsorption and desorption capacity of condensate gas according to claim 1, characterized in that: The free space volume V1 in step S2 is calculated by using the ideal gas state equation.

3. The method for testing the adsorption and desorption capacity of condensate gas according to claim 1, characterized in that: In step S3, P A The setting basis is that the pressure after the reference cylinder A (6) and the sample cylinder (18) are connected is 0.5 MPa higher than the dew point pressure of the condensate gas to prevent the occurrence of reverse condensation during the gas injection process.

4. The method for testing the adsorption and desorption capacity of condensate gas according to claim 1, characterized in that: The purpose of connecting the reference cylinder A (6), the reference cylinder B (11) and the sample cylinder (18) in step S3 is to ensure that the pressure in the system is above the dew point pressure and that the mixed gas satisfies the composition of the condensate gas; the mixed gas components reduce the condensate gas components, that is, after the mixed gas in the reference cylinder B (11) is injected into the system and mixed with the methane in the reference cylinder A (6) and the sample cylinder (18), the gas components reduce the condensate gas components.

5. A method for testing the adsorption and desorption capacity of condensate gas according to claim 4, characterized in that: The mixed gas in the mixed gas cylinder in step S3 is the methane component under equivalent pressure plus the gas component after the mixed gas component is reduced to the condensate gas component; that is, the molar number of methane in the methane in the reference cylinder A (6) and the sample cylinder (18) is n a , the number of moles of methane in the reference cylinder B (11) is n b , n a +n b is the total number of moles of methane in the equivalent condensate gas.

6. The method for testing the adsorption and desorption capacity of condensate gas according to claim 1, characterized in that: In step S3, the initial point P x The adsorption amount of condensate gas is calculated by the following formula: When the pressure is increased by the gradient, the pressure point P i The adsorption amount was calculated by the following formula: V x is the adsorption amount of condensate gas, cm 3 / g; V A 、V B 、V C and V are the volumes of reference cylinder A (6), reference cylinder B (11), reference cylinder C (15) and sample cylinder (18), respectively, cm 3 ;P A and P B are the set pressures of reference cylinder A (6) and reference cylinder B (11), MPa; V1 and V2 are the measured free space volumes of the first and second systems, cm 3 .

7. The method for testing the adsorption and desorption capacity of condensate gas according to claim 1, characterized in that: In the step S5, condensate oil will appear in the reverse condensation process. The proportion of condensate oil volume at different pressures under temperature T in the total oil and gas volume is obtained through the constant mass expansion experiment of condensate gas. The volume of condensate oil is obtained by the above method, thereby eliminating the error caused by the reverse condensation phenomenon in the desorption process of condensate gas. The desorption amount of condensate gas at the pressure point P1 in the desorption stage is calculated by the following formula: V JX is the amount of desorbed gas, cm 3 ;P max is the end point pressure of the adsorption experiment, MPa; V max is the end point pressure of the adsorption experiment max Adsorption capacity under 3 ;P out is the pressure of the gas collection device, MPa; V out is the volume of the gas collection device, cm 3 ; N is the percentage of condensate measured by constant mass expansion experiment, %; P1 is the pressure at each measuring point, MPa.

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