Reservoir water sensitivity evaluation device and method considering oil saturation

Abstract

The invention provides a reservoir water sensitivity evaluation device and method considering oil saturation, and belongs to the technical field of petroleum and natural gas development, the device comprises a displacement system, a stratum simulation system, a pressure monitoring system, a working fluid invasion simulation system, a back pressure control system and a metering system; the displacement system comprises a plurality of displacement units and a first four-way valve, and the displacement units are connected with an inlet of the first four-way valve. The stratum simulation system comprises a first high-pressure displacement pump, a core holder and a drying oven; the pressure monitoring system comprises a seventh needle valve and a pressure gauge; the working fluid invasion simulation system comprises a plurality of displacement units and a second four-way valve; the back pressure control system comprises a displacement unit and a back pressure valve. According to the method, the real formation temperature and pressure conditions are effectively simulated, the oil saturation of the reservoir is considered, the contact sequence and invasion direction of the drilling fluid, the fracturing fluid and the formation in the drilling and production process are considered, and the reservoir water sensitivity condition can be reflected more truly.

Description

Technical Field

[0001] The invention belongs to the technical field of oil and gas development, and in particular relates to a reservoir water sensitivity evaluation device and method taking oil saturation into consideration. Background Art

[0002] Reservoir sensitivity refers to the changes in reservoir physical properties caused by the type of fluid entering the reservoir, flow rate, and stress changes. It is a very complex change process. Before drilling and production, the formation rock and its mineral components and the fluids contained therein are basically stable in terms of physics, chemistry, and hydrodynamics. However, with the continuous progress of the drilling and production industry, especially the invasion of drilling fluid during drilling, the contact between fracturing fluid and formation during fracturing, and the extraction of crude oil in the formation, the original balance of the formation is broken, causing reservoir sensitivity problems.

[0003] The experimental data of reservoir sensitivity evaluation is the basic data for oil and gas field exploration and development, and is also the basic data that must be referred to before designing various well fluids. Therefore, it can more accurately simulate the actual drilling and production process. At the same time, the reservoir sensitivity evaluation that considers the original conditions of the oil and gas reservoir is of greater significance for the protection, increase and stability of an oil and gas reservoir.

[0004] At present, the evaluation of reservoir sensitivity is mainly based on the industry recommended standard "SY / T 5358-2010 Reservoir Sensitivity Flow Test Evaluation Method". The standard requires that before conducting a sensitivity flow test, the original fluid (including oil) in the rock sample must be completely cleaned, and the measurement temperature conditions must be room temperature and the pressure must not exceed 5MPa.

[0005] Chinese invention patent CN110566195B discloses an experimental method for evaluating the stress sensitivity of gas reservoirs under formation conditions with consideration of bound water, including core preparation, fluid preparation, establishment of formation temperature and pressure conditions, establishment of core bound water saturation, stress sensitivity evaluation experiment, permeability calculation at each test point of the stress sensitivity experiment, experimental conclusions, and other steps, and the gas reservoir production capacity of the reservoir to which the core used in the experiment belongs is evaluated and predicted based on the stress sensitivity damage degree obtained from the experimental conclusions. The present invention effectively simulates the temperature and pressure conditions of the actual gas reservoir formation, and fully considers the influence of the formation bound water. The measurement results are more in line with production practice, and the experimental data has high utilization value. Through the experiment, the reservoir stress sensitivity in the production process can be more realistically simulated, and the existing measurement method does not consider the influence of the formation bound water and temperature on the experimental results of the gas reservoir stress sensitivity evaluation, and provides an experimental method for obtaining more valuable gas reservoir stress sensitivity evaluation experimental data. This invention effectively simulates the temperature and pressure of the real formation, and takes into account the influence of bound water in the gas reservoir. Compared with oil reservoir development, in order to more realistically simulate the drilling and production process of the oil reservoir, it is also necessary to consider the oil saturation of the original formation and the influence of the working fluid (drilling fluid, fracturing fluid) invading the formation, which is more meaningful for the development of the oil reservoir.

[0006] Therefore, it is necessary to further simulate the actual drilling and production process and establish a reservoir water sensitivity evaluation method that conforms to actual production. Summary of the invention

[0007] In response to the problems existing in the above-mentioned prior art, the present invention provides a reservoir water sensitivity evaluation device and method taking into account oil saturation. The technical problem to be solved by the present invention is to consider the oil saturation of the reservoir, while taking into account the order of contact and invasion direction of the drilling fluid and fracturing fluid with the formation during the drilling process, so as to truly reflect the water sensitivity of the reservoir.

[0008] In order to solve the above technical problems, the present invention provides a reservoir water sensitivity evaluation device considering oil saturation, including a displacement system, a formation simulation system, a pressure monitoring system, a working fluid invasion simulation system, a back pressure control system and a metering system;

[0009] The displacement system includes a plurality of displacement units and a first four-way valve, wherein the plurality of displacement units are respectively connected to the inlet of the first four-way valve; the formation simulation system includes a first high-pressure displacement pump, a core clamp and an oven, wherein one end of the first high-pressure displacement pump is connected to the core clamp, the core clamp is arranged inside the oven, and one side of the core clamp is connected to the first four-way valve; the pressure monitoring system includes a seventh needle valve and a pressure gauge, wherein the seventh needle valve is arranged on a pipeline connecting the core clamp and the first four-way valve, and a plurality of pressure gauges are arranged on pipelines on both sides of the core clamp; the working fluid invasion simulation system includes a plurality of displacement units and a second four-way valve, wherein the plurality of displacement units are respectively connected to the inlet of the second four-way valve, and the second four-way valve is connected to one side of the core clamp; the back pressure control system includes a displacement unit and a back pressure valve, wherein the displacement unit is connected to the inlet of the back pressure valve, and the back pressure valve is connected to the outlet of the second four-way valve; the metering system includes a gas meter and a gas-liquid separator, wherein the upper part of the gas-liquid separator is connected to the back pressure valve, and the upper part of the gas-liquid separator is connected to the gas meter.

[0010] Further, the pressure gauge includes a first pressure gauge and a second pressure gauge, the first pressure gauge is arranged on the pipeline between the core holder and the seventh needle valve, and the second pressure gauge is arranged on the pipeline between the core holder and the second four-way valve.

[0011] Furthermore, the displacement unit includes a plurality of needle valves, a high-pressure displacement pump and an intermediate container. The needle valve is arranged on the pipeline connecting the high-pressure displacement pump and the intermediate container, and the needle valve is arranged on the pipeline connecting the high-pressure displacement pump and the four-way valve.

[0012] Furthermore, the displacement unit of the displacement system includes a second high-pressure displacement pump, a first needle valve, a fourth needle valve and a first intermediate container. The first needle valve is arranged on the pipeline connecting the second high-pressure displacement pump and the first intermediate container, and the fourth needle valve is arranged on the pipeline connecting the first intermediate container and the first four-way valve.

[0013] Furthermore, the displacement unit of the displacement system includes a third high-pressure displacement pump, a second needle valve, a fifth needle valve, a second intermediate container and a third intermediate container, the second needle valve is arranged on the pipeline connecting the third high-pressure displacement pump and the second intermediate container, and the fifth needle valve is arranged on the pipeline connecting the second intermediate container and the first four-way valve.

[0014] Furthermore, the displacement unit of the displacement system includes a fourth high-pressure displacement pump, a third needle valve, a sixth needle valve and a third intermediate container. The third needle valve is arranged on the pipeline connecting the fourth high-pressure displacement pump and the third intermediate container, and the sixth needle valve is arranged on the pipeline connecting the third intermediate container and the first four-way valve.

[0015] Furthermore, the displacement unit of the working fluid intrusion simulation system includes a sixth high-pressure displacement pump, a ninth needle valve, a fifth intermediate container and an eleventh needle valve; the ninth needle valve is arranged on the pipeline connecting the sixth high-pressure displacement pump and the fifth intermediate container, and the eleventh needle valve is arranged on the pipeline connecting the fifth intermediate container and the second four-way valve.

[0016] Furthermore, the displacement unit of the working fluid intrusion simulation system includes a seventh high-pressure displacement pump, an eighth needle valve, a fourth intermediate container and a tenth needle valve. The eighth needle valve is arranged on the pipeline connecting the seventh high-pressure displacement pump and the fourth intermediate container, and the tenth needle valve is arranged on the pipeline connecting the fourth intermediate container and the second four-way valve.

[0017] Furthermore, the displacement unit of the back pressure control system includes a fourteenth needle valve, a fifth high-pressure displacement pump, a sixth intermediate container and a thirteenth needle valve; the fourteenth needle valve is arranged on the pipeline connecting the fifth high-pressure displacement pump and the sixth intermediate container, and the thirteenth needle valve is arranged on the pipeline connecting the sixth intermediate container and the back pressure valve.

[0018] The present invention provides a reservoir water sensitivity evaluation method considering oil saturation, using the reservoir water sensitivity evaluation device considering oil saturation, comprising the following steps:

[0019] Step S1: Select a core and measure the core data;

[0020] Step S2: loading oil samples, formation water samples and distilled water samples into the displacement system, loading drilling fluid and fracturing fluid into the working fluid invasion simulation system, and loading nitrogen into the back pressure control system;

[0021] Step S3: placing the core into the formation simulation system, and using the displacement system to perform oil displacement. When the displacement volume reaches a set multiple of the pore volume, the displacement system is adjusted to perform constant pressure displacement to achieve oil saturation treatment of the core;

[0022] Step S4: using the displacement system to displace formation water, and when no oil flows out of the gas-liquid separator in the metering system, drying the core and weighing it, and then calculating the residual oil saturation of the core;

[0023] Step S5: Use the displacement system to displace formation water, and when the reading of the first pressure gauge is stable, record the pressure displayed by the first pressure gauge and the second pressure gauge respectively, and calculate the permeability measured by formation water under the residual oil saturation of the core;

[0024] Step S6: repeating step S3 to re-saturate the core with oil, and using the working fluid invasion simulation system to displace the drilling fluid and fracturing fluid into the core to simulate the working fluid invading the formation;

[0025] Step S7: displacing formation water using the displacement system, and when the first pressure gauge reading is stable for the i-th time, respectively record the pressure displayed by the first pressure gauge, the pressure displayed by the second pressure gauge, and the volume of the oil sample in the gas-liquid separator; until the volume of the oil sample in the gas-liquid separator no longer increases, record the final volume of the collected oil sample, and then calculate the core oil saturation corresponding to the i-th stable reading of the first pressure gauge and the permeability measured with formation water under the core oil saturation;

[0026] Step S8: using a displacement system to displace distilled water to contact the core, simulating distilled water contacting the formation, and calculating the permeability of the core with distilled water under residual oil saturation;

[0027] Step S9: Finish the experiment by taking out the core and drying it, weighing it and recording it as m e , unit is g, and then the corresponding water-sensitive damage rate under different core oil saturations is calculated.

[0028] Furthermore, in step S1, a core plug sample is selected to measure the length, diameter, initial weight, porosity and permeability of the core.

[0029] Furthermore, in step S3, the calculation formula of the pore volume is:

[0030]

[0031] Where V is the pore volume, cm 3 ; D is the core diameter, cm; L is the core length, cm; Φ0-core porosity, %.

[0032] Furthermore, in step S4, the residual oil saturation of the core is calculated according to the following formula:

[0033]

[0034] Among them, S or is the residual oil saturation of the core, %; m r is the weight of the core after drying, g; ρ o is the density of the oil sample, g / cm 3 .

[0035] Furthermore, in step S5, the permeability measured by formation water under the residual oil saturation of the core is calculated according to the following formula:

[0036]

[0037] Among them, K or is the permeability measured by formation water at residual oil saturation in the core, mD; Q is the constant displacement speed of the third high-pressure displacement pump in the displacement system, cm 3 / s; L is the core length, cm; μ 地 is the formation water viscosity, mPa·s; P1 is the pressure recorded by the first pressure gauge, atm; P2 is the pressure recorded by the second pressure gauge, atm.

[0038] Furthermore, in step S7, the core oil saturation corresponding to the first pressure gauge reading being stable for the i-th time is calculated according to the following formula:

[0039]

[0040] Among them, S oi is the oil saturation of the core, %; V o is the final collected oil sample volume of the gas-liquid separator, cm 3 ; V oi The volume of oil sample in the gas-liquid separator when the first pressure gauge reading is stable for the i-th time, cm 3 ; m0-initial weight of the core.

[0041] Furthermore, in step S7, the permeability measured by formation water under the oil saturation of the core is calculated according to the following formula:

[0042]

[0043] Among them, K oi -Permeability measured with formation water at oil saturation in the core, mD;

[0044] P 1i - When the formation water is used to drive the first pressure gauge until the reading of the first pressure gauge is stable for the ith time, the first pressure gauge displays the pressure, atm;

[0045] P 2i-When the formation water is pumped until the reading of the first pressure gauge stabilizes for the i-th time, the second pressure gauge displays the pressure, atm.

[0046] Furthermore, in step S8, the permeability measured with distilled water at the residual oil saturation of the core is calculated according to the following formula:

[0047]

[0048] Among them, K or蒸 -Permeability measured with distilled water at residual oil saturation in the core, mD;

[0049] μ 蒸 -Viscosity of distilled water, mPa·s;

[0050] P 1蒸 - Use distilled water to drive until the reading of the first pressure gauge 16 is stable, and the first pressure gauge 16 displays pressure, atm;

[0051] P 2蒸 - Use distilled water to displace until the reading of the first pressure gauge 16 is stable, and the second pressure gauge 18 displays the pressure, atm.

[0052] Furthermore, in step S9, the water-sensitive damage rate D corresponding to the core oil saturation is wi Calculate according to the following formula:

[0053]

[0054] Among them, D wi -Oil saturation S oi The corresponding water-sensitive damage rate is %.

[0055] The present invention provides a reservoir water sensitivity evaluation device and method taking oil saturation into consideration, which has the following advantages:

[0056] (1) Existing sensitivity tests do not take into account the impact of drilling fluid and fracturing fluid invading the formation during drilling and fracturing. The improvement of the experimental device in the present invention takes into account the impact of the two working fluids and the directions in which the two working fluids invade the formation, thereby simulating the production process more realistically.

[0057] (2) During reservoir development, existing tests on the sensitivity of core samples do not take oil saturation into account, which is different from the actual situation of the formation. At the same time, the sensitivity of the oil layer is more meaningful for reservoir development. Compared with the existing methods, the implementation process of the present invention takes the oil saturation of the sample into account.

[0058] The reservoir water sensitivity evaluation device and method taking oil saturation into consideration in the present invention effectively simulates the actual formation temperature and pressure conditions, takes the reservoir oil saturation into consideration, and takes into account the sequence of contact between the drilling fluid and the fracturing fluid and the formation and the invasion direction during the drilling and production process. It is highly consistent with the actual production situation and can more realistically reflect the reservoir water sensitivity situation. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Figure 1 It is a structural schematic diagram of a reservoir water sensitivity evaluation device taking oil saturation into consideration according to the present invention.

[0060] Figure 2 The present invention is a flow chart of a reservoir water sensitivity evaluation method taking oil saturation into consideration.

[0061] Among them, 1. the first high-pressure displacement pump; 2. the second high-pressure displacement pump; 3. the third high-pressure displacement pump; 4. the fourth high-pressure displacement pump; 5. the first intermediate container; 6. the second intermediate container; 7. the third intermediate container; 8. the first needle valve; 9. the fourth needle valve; 10. the second needle valve; 11. the fifth needle valve; 12. the third needle valve; 13. the sixth needle valve; 14. the first four-way valve; 15. the seventh needle valve; 16. the first pressure gauge; 17. the core holder; 18. the second pressure gauge; 19. Fourth intermediate container; 20. Eighth needle valve; 21. Tenth needle valve; 22. Second four-way valve; 23. Fifth intermediate container; 24. Ninth needle valve; 25. Eleventh needle valve; 26. Twelfth needle valve; 27. Back pressure valve; 28. Gas-liquid separator; 29. ​​Gas meter; 30. Sixth high-pressure displacement pump; 31. Seventh high-pressure displacement pump; 32. Thirteenth needle valve; 33. Sixth intermediate container; 34. Fourteenth needle valve; 35. Fifth high-pressure displacement pump; 36. Oven. DETAILED DESCRIPTION

[0062] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0063] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0064] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0065] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0066] In order to better understand the purpose, structure and function of the present invention, a reservoir water sensitivity evaluation device and method considering oil saturation of the present invention are further described in detail below in conjunction with the accompanying drawings.

[0067] Embodiment 1:

[0068] like Figure 1 As shown, a reservoir water sensitivity evaluation device considering oil saturation includes a displacement system, a formation simulation system, a pressure monitoring system, a working fluid invasion simulation system, a back pressure control system and a metering system;

[0069] The displacement system includes a plurality of displacement units and a first four-way valve 14, wherein the plurality of displacement units are respectively connected to the inlets of the first four-way valve;

[0070] The formation simulation system includes a first high-pressure displacement pump 1, a core holder 17 and an oven 36, one end of the first high-pressure displacement pump 1 is connected to the core holder 17, the core holder 17 is arranged inside the oven 36, and one side of the core holder 17 is connected to the first four-way valve 14;

[0071] The pressure monitoring system includes a seventh needle valve 15 and a pressure gauge. The seventh needle valve 15 is arranged on the pipeline connecting the core holder 17 and the first four-way valve 14. A plurality of pressure gauges are arranged on the pipelines on both sides of the core holder 17.

[0072] The working fluid invasion simulation system includes a plurality of displacement units and a second four-way valve 22, wherein the plurality of displacement units are respectively connected to the inlet of the second four-way valve 22, and the second four-way valve 22 is connected to one side of the core holder 17;

[0073] The back pressure control system includes a displacement unit and a back pressure valve 27, the displacement unit is connected to the inlet of the back pressure valve 27, and the back pressure valve 27 is connected to the outlet of the second four-way valve 22;

[0074] The metering system includes a gas meter 29 and a gas-liquid separator 28 . The upper portion of the gas-liquid separator 28 is connected to the back pressure valve 27 , and the upper portion of the gas-liquid separator 28 is connected to the gas meter 29 .

[0075] Embodiment 2:

[0076] like Figure 1 As shown, a reservoir water sensitivity evaluation device considering oil saturation includes a displacement system, a formation simulation system, a pressure monitoring system, a working fluid invasion simulation system, a back pressure control system and a metering system;

[0077] The displacement system includes a plurality of displacement units and a first four-way valve 14, wherein the plurality of displacement units are respectively connected to the inlets of the first four-way valve;

[0078] The formation simulation system includes a first high-pressure displacement pump 1, a core holder 17 and an oven 36, one end of the first high-pressure displacement pump 1 is connected to the core holder 17, the core holder 17 is arranged inside the oven 36, and one side of the core holder 17 is connected to the first four-way valve 14;

[0079] The pressure monitoring system includes a seventh needle valve 15 and a pressure gauge. The seventh needle valve 15 is arranged on the pipeline connecting the core holder 17 and the first four-way valve 14. A plurality of pressure gauges are arranged on the pipelines on both sides of the core holder 17.

[0080] The working fluid invasion simulation system includes a plurality of displacement units and a second four-way valve 22, wherein the plurality of displacement units are respectively connected to the inlet of the second four-way valve 22, and the second four-way valve 22 is connected to one side of the core holder 17;

[0081] The back pressure control system includes a displacement unit and a back pressure valve 27, the displacement unit is connected to the inlet of the back pressure valve 27, and the back pressure valve 27 is connected to the outlet of the second four-way valve 22;

[0082] The metering system includes a gas meter 29 and a gas-liquid separator 28 . The upper portion of the gas-liquid separator 28 is connected to the back pressure valve 27 , and the upper portion of the gas-liquid separator 28 is connected to the gas meter 29 .

[0083] The difference between this embodiment and the first embodiment is that:

[0084] The displacement unit includes a plurality of needle valves, a high-pressure displacement pump and an intermediate container. The needle valve is arranged on the pipeline connecting the high-pressure displacement pump and the intermediate container, and the needle valve is arranged on the pipeline connecting the high-pressure displacement pump and the four-way valve. The specific connection relationship is as follows:

[0085] The displacement unit of the displacement system includes a second high-pressure displacement pump 2, a third high-pressure displacement pump 3, a fourth high-pressure displacement pump 4, a first needle valve 8, a second needle valve 10, a third needle valve 12, a fourth needle valve 9, a fifth needle valve 11, a sixth needle valve 13, a first intermediate container 5, a second intermediate container 6 and a third intermediate container 7;

[0086] The first needle valve 8 is disposed on the pipeline connecting the second high-pressure displacement pump 2 and the first intermediate container 5, and the fourth needle valve 9 is disposed on the pipeline connecting the first intermediate container 5 and the first four-way valve 14;

[0087] The second needle valve 10 is arranged on the pipeline connecting the third high-pressure displacement pump 3 and the second intermediate container 6, and the fifth needle valve 11 is arranged on the pipeline connecting the second intermediate container 6 and the first four-way valve 14;

[0088] The third needle valve 12 is disposed on the pipeline connecting the fourth high-pressure displacement pump 4 and the third intermediate container 7 , and the sixth needle valve 13 is disposed on the pipeline connecting the third intermediate container 7 and the first four-way valve 14 .

[0089] The displacement unit of the working fluid intrusion simulation system includes a sixth high-pressure displacement pump 30, a seventh high-pressure displacement pump 31, an eighth needle valve 20, a ninth needle valve 24, a fourth intermediate container 19, a fifth intermediate container 23, a tenth needle valve 21 and an eleventh needle valve 25;

[0090] The ninth needle valve 24 is disposed on the pipeline connecting the sixth high-pressure displacement pump 30 and the fifth intermediate container 23 , and the eleventh needle valve 25 is disposed on the pipeline connecting the fifth intermediate container 23 and the second four-way valve 22 ;

[0091] The eighth needle valve 20 is disposed on the pipeline connecting the seventh high-pressure displacement pump 31 and the fourth intermediate container 19 , and the tenth needle valve 21 is disposed on the pipeline connecting the fourth intermediate container 19 and the second four-way valve 22 .

[0092] The displacement unit of the back pressure control system includes a fourteenth needle valve 34, a fifth high pressure displacement pump 35, a sixth intermediate container 33 and a thirteenth needle valve 32;

[0093] The fourteenth needle valve 34 is disposed on the pipeline connecting the fifth high-pressure displacement pump 35 and the sixth intermediate container 33 , and the thirteenth needle valve 32 is disposed on the pipeline connecting the sixth intermediate container 33 and the back-pressure valve 27 .

[0094] The pressure gauge includes a first pressure gauge 16 and a second pressure gauge 18 . The first pressure gauge 16 is disposed on the pipeline between the core holder 17 and the seventh needle valve 15 , and the second pressure gauge 18 is disposed on the pipeline between the core holder 17 and the second four-way valve 22 .

[0095] The first intermediate container 5, the second intermediate container 6, the third intermediate container 7, the first needle valve 8, the fourth needle valve 9, the second needle valve 10, the fifth needle valve 11, the third needle valve 12, the sixth needle valve 13, the first four-way valve 14, the seventh needle valve 15, the first pressure gauge 16, the core clamp 17, the second pressure gauge 18, the fourth intermediate container 19, the eighth needle valve 20, the tenth needle valve 21, the second four-way valve 22, the fifth intermediate container 23, the ninth needle valve 24, the eleventh needle valve 25 and the twelfth needle valve 26 are all arranged inside the oven 36, and the other components are arranged outside the oven 36.

[0096] The working process of a reservoir water sensitivity evaluation device considering oil saturation in this embodiment is as follows:

[0097] Ⅰ. Sampling: Select core plug samples and measure their length, diameter, weight, porosity and permeability. When measuring the core porosity and permeability, the samples are not washed with oil and gas is used for testing. The specific test methods refer to the national standard GB / T29172-2012;

[0098] II. Fluid preparation: The sample ends of the first intermediate container 5, the second intermediate container 6 and the third intermediate container 7 are respectively loaded with oil samples, formation water samples and distilled water samples; the sample end of the sixth intermediate container 33 is loaded with nitrogen; the sample end of the fourth intermediate container 19 is loaded with drilling fluid, and the sample end of the fifth intermediate container 23 is loaded with fracturing fluid;

[0099] III. Core saturated with oil: Place the sample in the core holder 17, apply confining pressure to the formation pressure using the first high-pressure displacement pump 1, heat it to the formation temperature using the oven 36 and keep it constant, open the thirteenth needle valve 32 and the fourteenth needle valve 34, pressurize the back pressure valve 27 to less than 5MPa of the formation pressure using the fifth high-pressure displacement pump 35, and then keep the fifth high-pressure displacement pump 35 constant pressure. Open the first needle valve 8, the fourth needle valve 9, the seventh needle valve 15 and the twelfth needle valve 26 in sequence, use the second high-pressure displacement pump 2 to displace at a constant speed of 0.1cm3 / min, and when the displacement volume reaches 10-15 times the pore volume V, close the twelfth needle valve 26, adjust the second high-pressure displacement pump 2 to a constant pressure of 1MPa higher than the pressure displayed on the pressure gauge 18, so that the oil sample fully saturates the core, and the saturation time is 12h. The pore volume V is calculated according to the following formula:

[0100]

[0101] Where V is the pore volume, cm 3 ;

[0102] D-core diameter, cm;

[0103] L-core length, cm;

[0104] Φ0-core porosity, %;

[0105] IV. Obtaining the residual oil saturation of the core: close the second high-pressure displacement pump 2, the first needle valve 8 and the fourth needle valve 9, open the twelfth needle valve 26, the second needle valve 10 and the fifth needle valve 11, use the third high-pressure displacement pump 3 to displace at a constant speed of 0.1 cm3 / min until no oil outflow is observed in the gas-liquid separator 28, close the third high-pressure displacement pump 3, depressurize the first high-pressure displacement pump 1 to atmospheric pressure, and slowly depressurize the fifth high-pressure displacement pump 35 to normal pressure, close the oven 36, and take out the core after the instrument cools to room temperature, dry it at low temperature (not higher than 60°C) and weigh it and record it as m r At this time, the residual oil saturation S of the core or Calculate according to the following formula:

[0106]

[0107] Among them, S or -Residual oil saturation of core, %;

[0108] m r -weight of the core after displacement, g;

[0109] ρ o -Oil sample density, g / cm 3 ;

[0110] V. Using formation water to measure the permeability of the core at residual oil saturation: put the core displaced to the residual oil saturation back into the core holder 17, use the oven 36 to heat it to the formation temperature and then keep it constant, use the first high-pressure displacement pump 1 to apply confining pressure to the formation pressure and then keep it constant, open the thirteenth needle valve 32 and the fourteenth needle valve 34, use the fifth high-pressure displacement pump 35 to pressurize the back pressure valve 27 to less than 5MPa of the formation pressure and then keep it constant. Open the second needle valve 10, the fifth needle valve 11 and the twelfth needle valve 26, use the third high-pressure displacement pump 3 to pressurize the back pressure valve 27 to 0.1cm 3 / min constant speed displacement, until the reading of the first pressure gauge 16 is stable, the pressure displayed on the first pressure gauge 16 is recorded as P1, and the pressure displayed on the second pressure gauge 18 is recorded as P2. At this time, the permeability Kor measured by formation water under the residual oil saturation of the core is calculated as follows:

[0111]

[0112] Among them, K or -Permeability measured with formation water at residual oil saturation in the core, mD;

[0113] Q-the speed of the constant displacement of the third high-pressure displacement pump 3 in the displacement system, cm 3 / s;

[0114] L-core length, cm;

[0115] μ 地 - formation water viscosity, mPa·s;

[0116] P1 - the first pressure gauge 16 records the pressure, atm;

[0117] P2 - the second pressure gauge 18 records the pressure, atm;

[0118] VI. Simulating the invasion of working fluid into the formation: Repeat step III to re-saturate the core with oil. Close the fifth needle valve 11 and the seventh needle valve 15, return the third high-pressure displacement pump 3 to normal pressure, and close the second needle valve 10. The eighth needle valve 20 and the tenth needle valve 21 are opened, and the seventh high-pressure displacement pump 31 is used for displacement, so that the drilling fluid in the fourth intermediate container 19 contacts the core from the tail end of the core holder 17, and the seventh high-pressure displacement pump 31 maintains a constant pressure for 2 hours at a pressure 1 MPa higher than the pressure displayed on the first pressure gauge 16, and the eighth needle valve 20 and the tenth needle valve 21 are closed, and the seventh high-pressure displacement pump 31 is stopped after retreating to normal pressure; the ninth needle valve 24 and the eleventh needle valve 25 are opened, and the sixth high-pressure displacement pump 30 is used for displacement, so that the fracturing fluid in the fifth intermediate container 23 contacts the core from the tail end of the core holder 17, and the sixth high-pressure displacement pump 30 maintains a constant pressure for 2 hours at a pressure 1 MPa higher than the pressure displayed on the first pressure gauge 16, and the ninth needle valve 24 and the eleventh needle valve 25 are closed, and the sixth high-pressure displacement pump 30 is stopped after retreating to normal pressure.

[0119] Ⅶ. After the working fluid contacts, use formation water to measure the permeability of the core at different oil saturations: open the second needle valve 10, the fifth needle valve 11, the seventh needle valve 15 and the twelfth needle valve 26, and use the third high-pressure displacement pump 3 to 0.1 cm 3 / min constant speed displacement, until the reading of the first pressure gauge 16 is stable for the i-th time, record the pressure displayed by the first pressure gauge 16 as P 1i , the second pressure gauge 18 shows a pressure of P 2i , the volume of oil sample in gas-liquid separator 28 is V oi Until the volume of the oil sample in the gas-liquid separator 28 stops increasing, the final collected oil sample volume is recorded as V o .

[0120] The core oil saturation S corresponding to the ith stable reading of the first pressure gauge 16 oi Calculate according to the following formula:

[0121]

[0122] Among them, S oi -Core oil saturation, %;

[0123] V o-The final volume of oil sample collected by gas-liquid separator 28, cm 3 ;

[0124] V oi -The volume of oil sample in the gas-liquid separator 28 when the reading of the first pressure gauge 16 is stable for the i-th time, cm 3 ;

[0125] The permeability Koi measured by formation water under the core oil saturation Soi is calculated as follows

[0126]

[0127] Among them, K oi - Permeability measured with formation water at core oil saturation Soi, mD;

[0128] P 1i - Displace with formation water until the reading of the first pressure gauge 16 is stable for the i-th time, and the first pressure gauge 16 records the pressure, atm;

[0129] P 2i - Displace with formation water until the reading of the first pressure gauge 16 is stable for the i-th time, and the second pressure gauge 18 records the pressure, atm;

[0130] VIII. Simulated distilled water contact formation: close the fifth needle valve 11, the third high pressure displacement pump 3 back to normal pressure, close the second needle valve 10, open the third needle valve 12 and the sixth needle valve 13, the fourth high pressure displacement pump 4 at 0.1cm 3 / min constant speed displacement, until the reading of the first pressure gauge 16 is stable, record the pressure displayed by the first pressure gauge 16 as P 1蒸 , the second pressure gauge 18 shows a pressure of P 2蒸 At this time, the permeability K is measured with distilled water under the residual oil saturation of the core. or蒸 Calculate according to the following formula

[0131]

[0132] Among them, K or蒸 -Permeability measured with distilled water at residual oil saturation in the core, mD;

[0133] μ 蒸 -Viscosity of distilled water, mPa·s;

[0134] P 1蒸 - Use distilled water to drive until the reading of the first pressure gauge 16 is stable, and the first pressure gauge 16 records the pressure, atm;

[0135] P 2蒸 - Use distilled water to drive until the reading of the first pressure gauge 16 is stable, and the second pressure gauge 18 records the pressure, atm;

[0136] IX. End of the experiment: turn off the fourth high-pressure displacement pump 4, slowly depressurize the fifth high-pressure displacement pump 35 to normal pressure, depressurize the first high-pressure displacement pump 1 to atmospheric pressure, turn off the oven 36, wait for the instrument to cool to room temperature, take out the core, dry it at low temperature (not higher than 60°C), and weigh it and record it as m e .

[0137] Ⅹ. Data processing:

[0138] Core with different oil saturation S oi The corresponding water sensitivity damage rate D wi Calculate according to the following formula:

[0139]

[0140] Among them, D wi -Oil saturation S oi The corresponding water-sensitive damage rate is %.

[0141] Embodiment 3:

[0142] like Figure 2 As shown, a reservoir water sensitivity evaluation method considering oil saturation includes the following steps:

[0143] Step S1: Select a core and measure the core data;

[0144] Step S2: loading oil samples, formation water samples and distilled water samples into the displacement system, loading drilling fluid and fracturing fluid into the working fluid invasion simulation system, and loading nitrogen into the back pressure control system;

[0145] Step S3: placing the core into the formation simulation system, and using the displacement system to perform oil displacement. When the displacement volume reaches a set multiple of the pore volume, the displacement system is adjusted to perform constant pressure displacement to achieve oil saturation treatment of the core;

[0146] Step S4: Use the displacement system to displace formation water. When no oil flows out of the gas-liquid separator 28 in the metering system, dry the core and weigh it, and then calculate the residual oil saturation of the core;

[0147] Step S5: Continue to use the displacement system to displace formation water until the reading of the first pressure gauge 16 is stable, respectively record the pressures displayed by the first pressure gauge 16 and the second pressure gauge 18, and calculate the permeability measured by formation water under the residual oil saturation of the core;

[0148] Step S6: repeating step S3 to re-saturate the core with oil, and using the working fluid invasion simulation system to displace the drilling fluid and fracturing fluid into the core to simulate the working fluid invading the formation;

[0149] Step S7: displacing formation water by using the displacement system, and when the reading of the first pressure gauge 16 is stable for the i-th time, respectively record the pressure displayed by the first pressure gauge 16, the pressure displayed by the second pressure gauge 18, and the volume of the oil sample in the gas-liquid separator 28; until the volume of the oil sample in the gas-liquid separator 28 stops increasing, record the final volume of the collected oil sample, and then calculate the core oil saturation corresponding to the i-th stable reading of the first pressure gauge 16 and the permeability measured by formation water under the core oil saturation;

[0150] Step S8: using a displacement system to displace distilled water to contact the core, simulating distilled water contacting the formation, and calculating the permeability of the core with distilled water under residual oil saturation;

[0151] Step S9: Finish the experiment by taking out the core and drying it, weighing it as me (unit: g), and then calculating the water-sensitive damage rate corresponding to different core oil saturations.

[0152] In the step S1, a core plug sample is selected to measure the length, diameter, initial weight, porosity and permeability of the core. When measuring the porosity and permeability, the core is not washed with oil and gas is used for testing. The specific testing method refers to the national standard GB / T29172-2012;

[0153] In the step S3, the core is placed in the core holder 17, and the confining pressure is applied to the formation pressure by the first high-pressure displacement pump 1. The temperature is raised to the formation temperature by the oven 36 and then kept constant. The thirteenth needle valve 32 and the fourteenth needle valve 34 are opened, and the back pressure valve 27 is pressurized to less than the formation pressure by the fifth high-pressure displacement pump 35, and then the fifth high-pressure displacement pump 35 maintains a constant pressure; the first needle valve 8, the fourth needle valve 9, the seventh needle valve 15 and the twelfth needle valve 26 are opened in sequence, and the second high-pressure displacement pump 2 is used to perform constant speed displacement. When the displacement volume reaches a set multiple of the pore volume, the twelfth needle valve 26 is closed, and the second high-pressure displacement pump 2 is adjusted to perform constant pressure displacement at a pressure higher than the pressure displayed on the pressure gauge 18, so that the oil sample fully saturates the core.

[0154] In step S3, the calculation formula of the pore volume is:

[0155]

[0156] Where V is the pore volume, cm 3 ; D is the core diameter, cm; L is the core length, cm; Φ0-core porosity, %;

[0157] In the step S4, the second high-pressure displacement pump 2, the first needle valve 8 and the fourth needle valve 9 are closed, the twelfth needle valve 26, the second needle valve 10 and the fifth needle valve 11 are opened, and the third high-pressure displacement pump 3 is used to displace at a constant speed until no oil outflow can be observed in the gas-liquid separator 28, the third high-pressure displacement pump 3 is closed, the first high-pressure displacement pump 1 is depressurized to atmospheric pressure, the fifth high-pressure displacement pump 35 is depressurized to normal pressure, the oven 36 is closed, and the core is taken out after the instrument is cooled to room temperature, the core is dried and weighed, and then the residual oil saturation of the core is calculated;

[0158] In step S4, the residual oil saturation of the core is calculated according to the following formula:

[0159]

[0160] Among them, S or -Residual oil saturation of core, %;

[0161] m r -The weight of the core after drying in step S4, g;

[0162] ρ o -Oil sample density, g / cm 3 ;

[0163] In the step S5, the core displaced to the residual oil saturation is put back into the core holder 17, the oven 36 is heated to the formation temperature and then kept at a constant temperature, the confining pressure is applied to the formation pressure by the first high-pressure displacement pump 1 and then kept at a constant pressure, the thirteenth needle valve 32 and the fourteenth needle valve 34 are opened, the back pressure valve 27 is pressurized to less than 5 MPa of the formation pressure by the fifth high-pressure displacement pump 35 and then kept at a constant pressure; the second needle valve 10, the fifth needle valve 11 and the twelfth needle valve 26 are opened, and the third high-pressure displacement pump 3 is used to perform constant speed displacement, and when the reading of the first pressure gauge 16 is stable, the pressure displayed by the first pressure gauge 16 and the pressure displayed by the second pressure gauge 18 are recorded respectively, and the permeability measured by formation water at the residual oil saturation of the core is calculated.

[0164] In step S5, the permeability measured by formation water under the residual oil saturation of the core is calculated as follows:

[0165]

[0166] Among them, K or -Permeability measured with formation water at residual oil saturation in the core, mD;

[0167] Q-the speed of the constant displacement of the third high-pressure displacement pump 3 in the displacement system, cm 3 / s;

[0168] L-core length, cm;

[0169] μ 地 - formation water viscosity, mPa·s;

[0170] P1 - the first pressure gauge 16 records the pressure, atm;

[0171] P2 - the second pressure gauge 18 records the pressure, atm;

[0172] In the step S6, the fifth needle valve 11 and the seventh needle valve 15 are closed, the third high-pressure displacement pump 3 is retreated to normal pressure, and the second needle valve 10 is closed; the eighth needle valve 20 and the tenth needle valve 21 are opened, and the seventh high-pressure displacement pump 31 is used for displacement, so that the drilling fluid in the fourth intermediate container 19 contacts the core from the tail end of the core holder 17, and the seventh high-pressure displacement pump 31 is kept at a constant pressure for 2 hours at a pressure 1MPa higher than the pressure displayed by the first pressure gauge 16, and the eighth needle valve 20 and the tenth needle valve 21 are closed, and the seventh high-pressure displacement pump 31 is stopped after retreating to normal pressure; the ninth needle valve 24 and the eleventh needle valve 25 are opened, and the sixth high-pressure displacement pump 30 is used for displacement, so that the fracturing fluid in the fifth intermediate container 23 contacts the core from the tail end of the core holder 17, and the sixth high-pressure displacement pump 30 is kept at a constant pressure for 2 hours, and the ninth needle valve 24 and the eleventh needle valve 25 are closed, and the sixth high-pressure displacement pump 30 is stopped after retreating to normal pressure.

[0173] In step S7, the second needle valve 10, the fifth needle valve 11, the seventh needle valve 15 and the twelfth needle valve 26 are opened, and the third high pressure displacement pump 3 is used to pump 0.1 cm 3 / min constant speed displacement, when the reading of the first pressure gauge 16 stabilizes for the i-th time, record the pressure displayed on the first pressure gauge 16, the pressure displayed on the second pressure gauge 18, and the volume of the oil sample in the gas-liquid separator 28; until the volume of the oil sample in the gas-liquid separator 28 stops increasing, record the final volume of the collected oil sample, and then calculate the core oil saturation corresponding to the i-th stable reading of the first pressure gauge 16 and the permeability measured with formation water at the core oil saturation.

[0174] In step S7, the core oil saturation corresponding to the ith stable reading of the first pressure gauge 16 is calculated according to the following formula:

[0175]

[0176] Among them, S oi is the oil saturation of the core, %;

[0177] V o The volume of oil sample finally collected by gas-liquid separator 28, cm 3 ;

[0178] V oi -The volume of oil sample in the gas-liquid separator 28 when the reading of the first pressure gauge 16 is stable for the i-th time, cm 3 ;

[0179] m0-initial weight of the core;

[0180] The permeability measured by formation water under core oil saturation is calculated as follows:

[0181]

[0182] Among them, K oi -Permeability measured with formation water at oil saturation in the core, mD;

[0183] P 1i - Displace with formation water until the reading of the first pressure gauge 16 is stable for the i-th time, and the first pressure gauge 16 displays pressure, atm;

[0184] P 2i - Displace with formation water until the reading of the first pressure gauge 16 is stable for the i-th time, and the second pressure gauge 18 displays the pressure, atm;

[0185] In step S8, the fifth needle valve 11 is closed, the third high pressure displacement pump 3 is returned to normal pressure, the second needle valve 10 is closed, the third needle valve 12 and the sixth needle valve 13 are opened, and the fourth high pressure displacement pump 4 is turned on at 0.1 cm 3 / min constant speed displacement, when the first pressure gauge 16 reading is stable, the pressure displayed on the first pressure gauge 16 and the pressure displayed on the second pressure gauge 18 are recorded respectively, and the permeability is measured with distilled water under the residual oil saturation of the core.

[0186] In step S8, the permeability measured with distilled water at the residual oil saturation of the core is calculated according to the following formula:

[0187]

[0188] Among them, K or蒸 -Permeability measured with distilled water at residual oil saturation in the core, mD;

[0189] μ 蒸 -Viscosity of distilled water, mPa·s;

[0190] P 1蒸 - Use distilled water to drive until the reading of the first pressure gauge 16 is stable, and the first pressure gauge 16 displays pressure, atm;

[0191] P 2蒸 - Use distilled water to drive until the reading of the first pressure gauge 16 is stable, and the second pressure gauge 18 displays the pressure, atm;

[0192] In step S9, the fourth high-pressure displacement pump 4 is turned off, the fifth high-pressure displacement pump 35 is slowly depressurized to normal pressure, the first high-pressure displacement pump 1 is depressurized to atmospheric pressure, the oven 36 is turned off, and the core is taken out after the instrument is cooled to room temperature, and the core is dried at low temperature (not higher than 60° C.) and weighed and recorded as m. e , unit: g.

[0193] In step S9, the water-sensitive damage rate D corresponding to different core oil saturations wi Calculate according to the following formula:

[0194]

[0195] Among them, D wi -Oil saturation S oi The corresponding water-sensitive damage rate is %.

[0196] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.

Claims

1. A reservoir water sensitivity evaluation device considering oil saturation, characterized in that: Including displacement system, formation simulation system, pressure monitoring system, working fluid invasion simulation system, back pressure control system and metering system; The displacement system includes a plurality of displacement units and a first four-way valve, wherein the plurality of displacement units are respectively connected to the inlet of the first four-way valve; the formation simulation system includes a first high-pressure displacement pump, a core clamp and an oven, wherein one end of the first high-pressure displacement pump is connected to the core clamp, the core clamp is arranged inside the oven, and one side of the core clamp is connected to the first four-way valve; the pressure monitoring system includes a seventh needle valve and a pressure gauge, wherein the seventh needle valve is arranged on a pipeline connecting the core clamp and the first four-way valve, and a plurality of pressure gauges are arranged on pipelines on both sides of the core clamp; the working fluid invasion simulation system includes a plurality of displacement units and a second four-way valve, wherein the plurality of displacement units are respectively connected to the inlet of the second four-way valve, and the second four-way valve is connected to one side of the core clamp; the back pressure control system includes a displacement unit and a back pressure valve, wherein the displacement unit is connected to the inlet of the back pressure valve, and the back pressure valve is connected to the outlet of the second four-way valve; the metering system includes a gas meter and a gas-liquid separator, wherein the upper part of the gas-liquid separator is connected to the back pressure valve, and the upper part of the gas-liquid separator is connected to the gas meter.

2. The reservoir water sensitivity evaluation device considering oil saturation according to claim 1, characterized in that: The pressure gauge comprises a first pressure gauge and a second pressure gauge. The first pressure gauge is arranged on the pipeline between the core holder and the seventh needle valve, and the second pressure gauge is arranged on the pipeline between the core holder and the second four-way valve.

3. The reservoir water sensitivity evaluation device considering oil saturation according to claim 1, characterized in that: The displacement unit includes a plurality of needle valves, a high-pressure displacement pump and an intermediate container. The needle valve is arranged on the pipeline connecting the high-pressure displacement pump and the intermediate container, and the needle valve is arranged on the pipeline connecting the high-pressure displacement pump and the four-way valve.

4. The reservoir water sensitivity evaluation device considering oil saturation according to claim 1, characterized in that: The displacement unit of the displacement system includes a second high-pressure displacement pump, a first needle valve, a fourth needle valve and a first intermediate container. The first needle valve is arranged on the pipeline connecting the second high-pressure displacement pump and the first intermediate container, and the fourth needle valve is arranged on the pipeline connecting the first intermediate container and the first four-way valve.

5. The reservoir water sensitivity evaluation device considering oil saturation according to claim 1, characterized in that: The displacement unit of the displacement system includes a third high-pressure displacement pump, a second needle valve, a fifth needle valve, a second intermediate container and a third intermediate container. The second needle valve is arranged on the pipeline connecting the third high-pressure displacement pump and the second intermediate container, and the fifth needle valve is arranged on the pipeline connecting the second intermediate container and the first four-way valve.

6. The reservoir water sensitivity evaluation device considering oil saturation according to claim 1, characterized in that: The displacement unit of the displacement system includes a fourth high-pressure displacement pump, a third needle valve, a sixth needle valve and a third intermediate container. The third needle valve is arranged on the pipeline connecting the fourth high-pressure displacement pump and the third intermediate container, and the sixth needle valve is arranged on the pipeline connecting the third intermediate container and the first four-way valve.

7. The reservoir water sensitivity evaluation device considering oil saturation according to claim 1, characterized in that: The displacement unit of the working fluid intrusion simulation system includes a sixth high-pressure displacement pump, a ninth needle valve, a fifth intermediate container and an eleventh needle valve; the ninth needle valve is arranged on the pipeline connecting the sixth high-pressure displacement pump and the fifth intermediate container, and the eleventh needle valve is arranged on the pipeline connecting the fifth intermediate container and the second four-way valve.

8. The reservoir water sensitivity evaluation device considering oil saturation according to claim 1, characterized in that: The displacement unit of the working fluid intrusion simulation system includes a seventh high-pressure displacement pump, an eighth needle valve, a fourth intermediate container and a tenth needle valve. The eighth needle valve is arranged on the pipeline connecting the seventh high-pressure displacement pump and the fourth intermediate container, and the tenth needle valve is arranged on the pipeline connecting the fourth intermediate container and the second four-way valve.

9. The reservoir water sensitivity evaluation device considering oil saturation according to claim 1, characterized in that: The displacement unit of the back pressure control system includes a fourteenth needle valve, a fifth high-pressure displacement pump, a sixth intermediate container and a thirteenth needle valve; the fourteenth needle valve is arranged on the pipeline connecting the fifth high-pressure displacement pump and the sixth intermediate container, and the thirteenth needle valve is arranged on the pipeline connecting the sixth intermediate container and the back pressure valve.

10. A reservoir water sensitivity evaluation method considering oil saturation, characterized in that: The reservoir water sensitivity evaluation device considering oil saturation as described in any one of claims 2 to 9 comprises the following steps: Step S1: Select a core and measure the core data; Step S2: loading oil samples, formation water samples and distilled water samples into the displacement system, loading drilling fluid and fracturing fluid into the working fluid invasion simulation system, and loading nitrogen into the back pressure control system; Step S3: placing the core into the formation simulation system, using the displacement system to perform oil displacement, and when the displacement volume reaches a set multiple of the pore volume, adjusting the displacement system to perform constant pressure displacement to achieve oil saturation treatment of the core; Step S4: using the displacement system to displace formation water, and when no oil flows out of the gas-liquid separator in the metering system, drying the core and weighing it, and then calculating the residual oil saturation of the core; Step S5: Use the displacement system to displace formation water, and when the reading of the first pressure gauge is stable, record the pressure displayed by the first pressure gauge and the second pressure gauge respectively, and calculate the permeability measured by formation water under the residual oil saturation of the core; Step S6: repeating step S3 to re-saturate the core with oil, and using the working fluid invasion simulation system to displace the drilling fluid and fracturing fluid into the core to simulate the working fluid invading the formation; Step S7: displacing formation water using the displacement system, and when the first pressure gauge reading is stable for the i-th time, respectively record the pressure displayed by the first pressure gauge, the pressure displayed by the second pressure gauge, and the volume of the oil sample in the gas-liquid separator; until the volume of the oil sample in the gas-liquid separator no longer increases, record the final volume of the collected oil sample, and then calculate the core oil saturation corresponding to the i-th stable reading of the first pressure gauge and the permeability measured with formation water under the core oil saturation; Step S8: using a displacement system to displace distilled water to contact the core, simulating distilled water contacting the formation, and calculating the permeability of the core with distilled water under residual oil saturation; Step S9: Finish the experiment by taking out the core and drying it, weighing it and recording it as m e , unit is g, and then the corresponding water-sensitive damage rate under different core oil saturations is calculated.

11. The reservoir water sensitivity evaluation method considering oil saturation according to claim 10, characterized in that: In step S1, a core plug sample is selected to measure the length, diameter, initial weight, porosity and permeability of the core.

12. The reservoir water sensitivity evaluation method considering oil saturation according to claim 10, characterized in that: In step S3, the calculation formula of the pore volume is: Where V is the pore volume, cm 3 ; D is the core diameter, cm; L is the core length, cm; Φ0-core porosity, %.

13. The reservoir water sensitivity evaluation method considering oil saturation according to claim 10, characterized in that: In step S4, the residual oil saturation of the core is calculated according to the following formula: Among them, S or is the residual oil saturation of the core, %; m r is the weight of the core after drying, g; ρ o is the density of the oil sample, g / cm 3 .

14. The reservoir water sensitivity evaluation method considering oil saturation according to claim 10, characterized in that: In step S5, the permeability measured by formation water under the residual oil saturation of the core is calculated according to the following formula: Among them, K or is the permeability measured by formation water under the residual oil saturation of the core, mD; Q is the constant displacement speed of the third high-pressure displacement pump in the displacement system, cm 3 / s; L is the core length, cm; μ 地 is the formation water viscosity, mPa·s; P1 is the pressure recorded by the first pressure gauge, atm; P2 is the pressure recorded by the second pressure gauge, atm.

15. The reservoir water sensitivity evaluation method considering oil saturation according to claim 10, characterized in that: In step S7, the core oil saturation corresponding to the first pressure gauge reading being stable for the i-th time is calculated according to the following formula: Among them, S oi is the oil saturation of the core, %; V o is the final collected oil sample volume of the gas-liquid separator, cm 3 ; V oi The volume of oil sample in the gas-liquid separator when the first pressure gauge reading is stable for the i-th time, cm 3 ; m0-initial weight of the core.

16. The reservoir water sensitivity evaluation method considering oil saturation according to claim 10, characterized in that: In step S7, the permeability measured by formation water under the oil saturation of the core is calculated according to the following formula: Among them, K oi -Permeability measured with formation water at oil saturation in the core, mD; P 1i - When the formation water is used to drive the first pressure gauge until the reading of the first pressure gauge is stable for the ith time, the first pressure gauge displays the pressure, atm; P 2i -When the formation water is pumped until the reading of the first pressure gauge stabilizes for the i-th time, the second pressure gauge displays the pressure, atm.

17. The reservoir water sensitivity evaluation method considering oil saturation according to claim 10, characterized in that: In step S8, the permeability measured with distilled water at the residual oil saturation of the core is calculated according to the following formula: Among them, K or蒸 -Permeability measured with distilled water at residual oil saturation in the core, mD; μ 蒸 -Viscosity of distilled water, mPa·s; P 1蒸 - Use distilled water to drive until the reading of the first pressure gauge 16 is stable, and the first pressure gauge 16 displays pressure, atm; P 2蒸 - Use distilled water to drive until the reading of the first pressure gauge 16 is stable, and the second pressure gauge 18 displays the pressure, atm.

18. The reservoir water sensitivity evaluation method considering oil saturation according to claim 10, characterized in that: In step S9, the water-sensitive damage rate D corresponding to the core oil saturation wi Calculate according to the following formula: Among them, D wi -Oil saturation S oi The corresponding water-sensitive damage rate is %.

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