A testing device and method for gas-water relative permeability of tight rocks under high temperature and high pressure

Abstract

The present invention relates to a test device and method for gas-water relative permeability of tight rocks under high temperature and high pressure, which includes a gas cylinder, a liquid pump, a throttle valve, a flowmeter, a thermometer, a pressure sensor, an intermediate container, a core holder, an confining pressure pump, a heating device, a gas densitometer, and a computer; the inlet end of the core holder is connected to the gas cylinder and the liquid pump respectively through two flowmeters, and a heating device is arranged; the outlet end of the core holder is connected to the flowmeter and the gas densitometer, and another set of heating device is arranged; heat insulation materials are arranged between the two sets of heating devices; the heating device includes a high-temperature resistant double-layer cylinder, a heating wire and heat insulation materials. If the absolute permeability of the core is not less than 1 mD, the steady-state method is used to test the gas-water relative permeability; if the absolute permeability of the core is less than 1 mD, the unsteady-state method of detecting the gas density at the outlet end is used to test the gas-water relative permeability. The present invention can accurately measure the gas-water relative permeability of tight rocks under high temperature and high pressure conditions.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and gas engineering, and particularly relates to oilfield development calculation, dynamic analysis, determination of gas-water saturation distribution in a reservoir, and gas displacement of water. Specifically, it is a test device and method for gas-water relative permeability of tight rocks under high temperature and high pressure. Background Art

[0002] The pore structure in tight rocks is complex, and the pore size, shape, and distribution characteristics are different. The gas-water relative permeability experiment conducted to deeply study the pore structure characteristics of tight rocks and the flow behavior of fluids therein can reveal the mixing state and distribution law of complex fluids in the pore system, and further clarify the distribution and flow conditions of each component in tight oil and gas reservoirs.

[0003] Currently, most of the determinations of gas-water relative permeability are based on the national standard GB / T 28912-2012 "Determination Method for Relative Permeability of Two-Phase Fluids in Rocks", which stipulates the steady-state method and the non-steady-state method for determining the relative permeability of gas-liquid two-phase fluids. It calculates the relative permeability of gas-liquid by measuring the gas-liquid two-phase flow rates at the outlet end face and substituting other parameters into the formula. However, for tight oil and gas reservoirs, the matrix has the characteristics of low porosity and low permeability, but microfractures are also developed to a certain extent. Therefore, before measuring the gas-water relative permeability, the gas-water relative permeability test method should be determined based on the absolute permeability of the core. When the core is relatively tight, the liquid output at its outlet end is extremely small during the experiment, and the traditional measurement method cannot accurately measure its flow rate, and the influence of formation high temperature and high pressure conditions on the fluid flow state in the rock is not considered. Therefore, considering the fluid flow under in-situ high temperature and high pressure conditions, accurately measuring the core outlet flow rate, and forming a test device and method for gas-water relative permeability of tight rocks under high temperature and high pressure can provide a basis for oilfield dynamic analysis and ensure the efficient development of tight oil and gas reservoirs. Summary of the Invention

[0004] In view of the above problems, the present invention aims to provide a test device and method for gas-water relative permeability of tight rocks considering in-situ reservoir conditions (i.e., reservoir temperature, pressure, and fluid occurrence state). This method can simulate in-situ temperature and pressure. When the connectivity of microfractures in the core is good, the steady-state method is adopted and the conventional measurement method is used for measurement; when the core is relatively tight, the non-steady-state method is adopted. Since the liquid output is extremely small and the conventional measurement method cannot be used to measure the liquid phase volume, the outlet pipeline can be heated to convert the liquid phase into a gas phase, and the volume fractions of the two components are calculated through a gas density meter and a flow meter, and then converted into the gas-liquid two-phase volume fractions at the target temperature by looking up the table, so as to calculate the gas-water relative permeability. This device and method overcome the shortcomings of the prior art and can measure the gas-water relative permeability of tight rocks more accurately, providing a basis for the development of tight oil and gas reservoirs.

[0005] A testing device for gas-water relative permeability of tight rocks under high temperature and high pressure provided by the present invention comprises a gas cylinder, a liquid pump, a throttle valve, a flowmeter, a thermometer, a pressure sensor, an intermediate container, a core holder, an confining pressure pump, a heating device, a gas densitometer and a computer. The gas outlet of the gas cylinder and the liquid outlet of the liquid pump are respectively connected to corresponding inlet flowmeters. Heating devices are arranged on the two inlet flowmeters, the core holder and the pipelines therebetween; the core holder is provided with a pipeline connected to the confining pressure pump; the left and right of the core holder are connected to the intermediate container and the pressure sensor; an outlet flowmeter and a gas densitometer are arranged on the subsequent pipeline at the outlet of the core holder, and another set of heating device is arranged on both of them. Heat insulation materials are arranged between the two sets of heating devices; the heating device comprises a high-temperature resistant double-layer cylinder, heat insulation materials and a thermometer. The outer layer of the cylinder is wrapped with heat insulation materials, and the heat insulation materials are wrapped with an outer shell. The inner layer of the cylinder is wound with a thermal resistance wire. The evaluation method using this device can more accurately measure the gas-water relative permeability by selectively using two methods, namely the steady state method or the unsteady state method, under in-situ conditions, so as to provide an effective basis for the development of tight oil and gas reservoirs.

[0006] The heating device comprises a high-temperature resistant double-layer cylinder which has a certain toughness and can be bent to a certain extent along with the pipeline; the cylinder is of a double-layer sandwich structure. A thermal resistance wire is wound on the inner layer cylinder for heating, and the heating temperature can be adjusted by adjusting the resistance wire. The outer layer cylinder is wrapped with heat insulation materials for heat preservation, and the heat insulation materials are wrapped with an outer shell.

[0007] To achieve the above technical objectives, the present invention provides the following experimental technical solutions, which specifically include the following steps:

[0008] Before the experiment, the core sample should be fully washed with oil, washed with salt and dried. Measure the core length L, diameter D and dry weight m0 of the core, and calculate the cross-sectional area A of the core; use the pressure pulse decay method to measure the core permeability K0, and use the vacuum pumping and pressurized water saturation method to measure the core porosity φ0; if the core permeability ≥ 1 mD, the steady state method is used to carry out the gas-water relative permeability test experiment; if the core permeability < 1 mD, the unsteady state method is used to carry out the gas-water relative permeability test experiment;

[0009] At the beginning of the experiment, all valves in the device are default closed. Put the core saturated with the experimental liquid into the core holder, and pressurize the confining pressure pump to the in-situ effective stress P w , and according to the selected gas-water relative permeability test method (steady state method or unsteady state method), adopt the following experimental scheme to carry out the test:

[0010] Scheme 1: Steady state method

[0011] Step 1, open the gas cylinder, open the control valve of the gas injection system, open the left and right valves of the core holder, and adjust the front and rear heating devices to the formation temperature T f ;

[0012] Step 2: Start displacing the core to establish the irreducible water saturation. After the inlet and outlet flow rates become stable, record the current time, the irreducible water saturation S wr and the formation temperature T f of the experimental gas flow rate q at the outlet under the conditions of g (S wr ), the inlet and outlet pressures p1(S wr ) and p2; close all experimental devices, take out the core, and record the core mass m1 at this time; calculate the volume V of the displaced liquid w0 and the irreducible water saturation S of the core wr ; calculate the effective gas permeability K wr of the core and the relative gas permeability K f under the conditions of the irreducible water saturation S g (S wr ) and the formation temperature T rg (S wr ):

[0013]

[0014] p2 = p a (3)

[0015]

[0016] where V w0 is the volume of the displaced liquid, cm 3 ; m0 is the dry weight of the core, g; m1 is the mass of the core after establishing the irreducible water saturation, g; ρ0 is the density of the experimental liquid at normal temperature, g / cm 3 ; S wr is the irreducible water saturation, %; V p is the pore volume, cm 3 ; p1(S wr ) and p2 are the inlet and outlet pressures under the conditions of the irreducible water saturation S wr and the formation temperature T f , where p2 is equal to the atmospheric pressure, MPa; p a is the atmospheric pressure, MPa; q g (S wr ) is the experimental gas flow rate at the outlet under the conditions of the irreducible water saturation S wr and the formation temperature T f , cm 3 / s; μ gf is the viscosity of the experimental gas at the formation temperature T f , mPa·s; L is the core length, cm; A is the core cross-sectional area, cm 2 ; K g (Swr ) and K rg (S wr ) are the effective gas permeability and relative gas permeability of the core under the conditions of irreducible water saturation S wr and formation temperature T f , mD; K0 is the initial permeability of the core, mD;

[0017] Step 3: Place the core with irreducible water saturation established into the holder, pump the confining pressure to the in-situ effective stress P w , open the gas cylinder, open the control valve of the gas injection system, open the left and right valves of the core holder, open the control valve of the liquid injection system, turn on the liquid pump, and adjust the front heating device to the formation temperature T f ;

[0018] Step 4: Through the gas-liquid injection system, inject gas and liquid into the rock sample according to the proportional flow rate. After the flow rate is stable, record the current time, the inlet and outlet pressures p1(S w ) and p2, and the flowmeter readings q f of the inlet gas and liquid under the conditions of water saturation S w ) and q g (S w ) and q w (S w ); Calculate the water saturation S w of the core at the current time; Calculate the two-phase effective permeability K w of the core at the current time under the conditions of water saturation S f and formation temperature T g (S w ), K w (S w ) and the two-phase relative permeability K f of the core at formation temperature T rg (S w ), K rw (S w ):

[0019]

[0020] Among them, S w is the water saturation of the core under the current injected gas-liquid flow rate ratio, %; q g (S w ) and q w (S w ) are the gas and water outlet flow rates under the conditions of water saturation S w and formation temperature T f , cm 3 / s; μ wf is the formation temperature Tf Viscosity of the lower liquid, mPa·s; p1(S w ) is the water saturation S w and the formation temperature T f Under the conditions of the inlet pressure, MPa; K g (S w ) and K w (S w ) are the effective gas and liquid permeabilities of the core at the water saturation S w and the formation temperature T f Under the conditions, mD; K rg (S w ) and K rw (S w ) are the relative gas and liquid permeabilities of the core at the water saturation S w and the formation temperature T f Under the conditions, mD;

[0021] Step 5: Reduce the gas / liquid flow rate ratio of the injected rock sample to increase the water saturation of the core. Repeat Step 4 for the remaining steps until the gas / liquid flow rate ratio equals 0, and then end the experiment.

[0022] Scheme 2: Unsteady state method

[0023] Step 1: Open the gas cylinder, open the control valve of the gas injection system, open the left and right valves of the core holder, and adjust the two heating devices to the formation temperature T f ;

[0024] Step 2: Start displacing the core to establish the irreducible water saturation. After the inlet and outlet flow rates are stable, close all experimental devices, remove the core, and record the core mass m1 at this time; calculate the volume of the displaced liquid V w0 , the irreducible water saturation S of the core wr ;

[0025]

[0026] Step 3: Re-saturate the core with the experimental liquid and then place it in the core holder. Pressurize the confining pressure pump to the in-situ effective stress P w ; Adjust the front heating device to the formation temperature T f , and adjust the rear heating device to the evaporation temperature T e , which is determined by the evaporation properties of the experimental injection fluid, to ensure that the fluid evaporates instantaneously when it enters the outlet pipeline of the core holder;

[0027] Step 4: Open the gas cylinder, open the control valve of the gas injection system, open the left and right valves of the core holder, start gas flooding, keep the inlet and outlet pressures constant during displacement, and record the outlet flow rate q at each moment e, density ρ of the outlet mixed gas e ;

[0028] Step 5, calculate the evaporation temperature T e Volume fractions s g of the experimental gas and water vapor v , and then calculate the evaporation temperature T e flows of the experimental gas and water vapor:

[0029]

[0030] q ge =q e ·s g (14)

[0031] q ve =q e ·s v (15)

[0032] where s g and s v are the volume fractions of the experimental gas and water vapor at the evaporation temperature T e , %; ρ ge and ρ ve are the densities of the experimental gas and water vapor at the temperature T e , g / cm 3 ; q ge and q ve are the flows of the experimental gas and water vapor at the temperature T e , mL / s;

[0033] Step 6, calculate the volume flows q f and q gf of the gas and liquid at the formation temperature T wf :

[0034] q gf ρ gf =q ge ρ ge (16)

[0035]

[0036] where ρ gf and ρ wf are the densities of the experimental gas and water at the temperature T f , g / cm 3 ; a f is the ratio of the volume of the solution to the volume of the solvent in the unit volume of the experimental liquid at the temperature T f ;

[0037] Step 7, calculate the formation temperature Tf Under the condition, the relative permeability K rg ′, K rw ′:

[0038]

[0039] where f g (S w ′) is the gas holdup in the outlet fluid per unit time, %; is the cumulative gas production volume, mL; is the cumulative outlet flow rate, mL; I is the flow capacity ratio; K rg ′ and K rw ′ are the gas-liquid two-phase relative permeabilities of the core under the water saturation S w ′ and the formation temperature T f condition, mD;

[0040] Step 8: Turn off all heating devices, clean the pipeline, and end the experiment.

[0041] Compared with the existing gas-water relative permeability test method, the advantages of the present invention are as follows:

[0042] (1) The present invention takes into account the influence of in-situ conditions, i.e., high temperature, high pressure and fluid occurrence state of the reservoir, on the gas-water relative permeability experiment, which is more in line with the working conditions during the development of tight oil and gas reservoirs.

[0043] (2) The present invention integrates two methods, namely the steady-state method and the unsteady-state method, of the gas-water relative permeability experiment in one device, reducing the floor area, with a relatively simple device and lower experimental cost.

[0044] (3) When the present invention measures the gas-water relative permeability by the unsteady-state method, the outlet liquid is converted into water vapor, and the liquid phase flow rate is indirectly measured by measuring the water vapor flow rate, improving the measurement accuracy. Description of the Drawings

[0045] Figure 1 is a schematic diagram of the relative high-permeability core gas-water relative permeability curve provided in the embodiment of the present invention;

[0046] Figure 2 is a schematic diagram of the relative low-permeability core gas-water relative permeability curve provided in the embodiment of the present invention;

[0047] Figure 3 is a schematic structural diagram of the test device for the gas-water relative permeability of tight rocks under high temperature and high pressure of the present invention;

[0048] In the figure: 1 - gas cylinder, 2 - pressure gauge of the first throttle valve, 3 - pressure gauge of the second throttle valve, 4 - throttle valve, 5 - first control valve, 6 - first flowmeter, 7 - liquid pump, 8 - second control valve, 9 - second flowmeter, 10 - first thermometer, 11 - first pressure sensor, 12 - second pressure sensor, 13 - first intermediate container, 14 - second intermediate container, 15 - third flowmeter, 16 - gas densitometer, 17 - second thermometer, 18 - third control valve, 19 - core holder, 20 - fourth control valve, 21 - fifth control valve, 22 - third pressure sensor, 23 - third intermediate container, 24 - computer, 25 - confining pressure pump, 26 - sixth control valve, ① - first heating device, ② - second heating device.

[0049] Figure 4 It is a schematic structural diagram of the heating device in the test device for the gas - water relative permeability of tight rocks under high temperature and high pressure of the present invention:

[0050] In the figure: 27 - outer shell, 28 - heat - insulating material, 29 - outer cylinder, 30 - heating resistance wire, 31 - inner cylinder. Specific implementation manner

[0051] The present invention will be described below with reference to the accompanying drawings. The description here is only for the illustration and explanation of the present invention, and its protection scope is not limited to the following.

[0052] As Figure 3 shown, a device for measuring the gas - water relative permeability of tight rocks under high temperature and high pressure includes a gas injection system, a liquid injection system, a confining pressure loading system, a core holder, a data acquisition system, and a heating system. The gas injection system and the liquid injection system are connected to the inlet of the core holder, and the confining pressure loading system is connected to the middle part of the core holder.

[0053] The gas injection system sequentially includes a gas cylinder 1, a pressure gauge of the first throttle valve 2, a pressure gauge of the second throttle valve 3, a throttle valve 4, a first control valve 5, and a first flowmeter 6 from left to right. The pressure gauge of the first throttle valve 2 and the pressure gauge of the second throttle valve 3 are installed on the throttle valve 4. The first flowmeter 6 and the subsequent pipelines are arranged in the front - part heating device and finally connected to the inlet end of the core holder.

[0054] The liquid injection system sequentially includes a liquid pump 7, a second control valve 8, and a second flowmeter 9 from left to right. The second flowmeter 9 and the subsequent pipelines are arranged in the front - part heating device and finally connected to the inlet end of the core holder.

[0055] The confining pressure loading system successively includes a pressure sensor 22, an intermediate container 23, a confining pressure pump 25, and a sixth control valve 26 from top to bottom. The sixth control valve 26 is a pressure loading / unloading switch for controlling the confining pressure pump 25. The third pressure sensor 22 and the third intermediate container 23 are used to detect the magnitude of the applied confining pressure, are connected to a computer, and the subsequent pipeline is connected to a core holder.

[0056] The data acquisition system includes a first flowmeter 6, a second flowmeter 9, a third flowmeter 15, a first pressure sensor 11, a second pressure sensor 12, a third pressure sensor 22, a first intermediate container 13, a second intermediate container 14, a third intermediate container 23, a gas densitometer 16, and a computer 24. All flowmeters (6, 9, 15), pressure sensors (11, 12, 22), and gas densitometers (23) are connected to the computer 24 to collect data. The first flowmeter 6 is used to collect the gas phase inlet flow rate, and the second flowmeter 9 is used to collect the liquid phase inlet flow rate. The first pressure sensor 11 and the first intermediate container 13, and the second pressure sensor 12 and the second intermediate container 14 are respectively arranged on the left and right of the core holder to collect the inlet and outlet pressures of the core holder. The third pressure sensor 22 and the third intermediate container 23 are arranged in the confining pressure loading system to collect the confining pressure. The third flowmeter 15 and the gas densitometer 16 are arranged at the gas outlet to collect the outlet gas flow rate and density.

[0057] The heating system includes a front part heating device, a rear part heating device, a first thermometer 10, and a second thermometer 17. The first thermometer 10 is installed on the front part heating device, and the second thermometer 17 is installed on the rear part heating device. The part where the front part heating device acts includes the first flowmeter 6, the second flowmeter 9, the third control valve 18, the core holder 19, and the corresponding pipeline. The part where the rear part heating device acts includes the fourth control valve 20, the fifth control valve 21, the third flowmeter 15, the gas densitometer 16, and the corresponding pipeline. Heat insulation materials are arranged between the front part heating device and the rear part heating device, that is, at the outlet of the core holder.

[0058] The heating device has a structure as Figure 4 shown, and includes a housing 27, a heat insulation material 28, an outer cylinder 29, a heating resistance wire 30, and an inner cylinder 31. The structure is specifically described as a high-temperature resistant double-layer cylinder. This double-layer cylinder has a certain toughness and can be bent to a certain extent along with the pipeline. The cylinder is a double-layer sandwich structure. The inner cylinder 31 is wound with a thermal resistance wire for heating, and the heating temperature can be adjusted by adjusting the heating resistance wire 30. The outer cylinder 29 is wrapped with a heat insulation material 28 for heat preservation, and the heat insulation material 28 is externally wrapped with a housing 27.

[0059] In a specific embodiment, the steps of the evaluation experiment method are as follows:

[0060] Step 1: Two core samples were taken from a gas field in the Ordos Basin. The core samples were thoroughly washed with salt and oil, dried, and the core length L, diameter D, and dry weight m0 of the core were measured. The cross-sectional area A of the core was calculated. According to the on-site data, the formation temperature was set at 120°C, the in-situ effective stress was 82 MPa, and the irreducible water saturation of the rock sample was 34%.

[0061] Step 2: The core permeability K0 was measured using the pressure pulse decay method, and the core porosity φ0 was measured using the vacuum pressurization saturation water phase method; the permeability of core ① was measured to be 2.644 mD in the experiment, and the steady-state method was selected for the experiment; the permeability of core ② was measured to be 0.110 mD in the experiment, and the non-steady-state method was selected for the experiment.

[0062] For the steady-state method used for core ①, the experimental steps are as follows:

[0063] (1) Place the core saturated with formation water under vacuum into the core holder, apply a confining pressure equal to the in-situ effective stress, i.e., P w = 82 MPa, adjust the two heating devices to the formation temperature T f = 120°C, turn on the gas injection system to start establishing the irreducible water saturation. After the inlet and outlet flows are stable, record the gas flow rate, inlet and outlet pressures, take out the core, and record the core mass m1 at this time; substitute the data into formulas (1) - (5) to calculate the irreducible water saturation S wr of the core and the gas-phase relative permeability K rg (S wr );

[0064] (2) Place the core with established irreducible water saturation into the holder, reapply a confining pressure equal to the in-situ effective stress, i.e., P w = 82 MPa, adjust the front heating device to the formation temperature T f = 120°C, inject gas and liquid into the rock sample according to the proportional flow rates. The gas-water ratios are 9:1, 4:1, 7:3, 3:2, 1:1, 2:3, 3:7, 1:4, 1:9, 0:1 respectively. Record the inlet and outlet pressures and the readings of the inlet two-phase flowmeter for each ratio experiment. After the flow is stable, substitute the data into formulas (6) - (10) to calculate the current water saturation S w of the core and the two-phase relative permeability at the water saturation S w and the formation temperature T f ;

[0065] (3) Plot the gas-water relative permeability curve based on the experimental results.

[0066] For the improved non-steady-state method used for core ②, the experimental steps are as follows:

[0067] (1) Measure the irreducible water saturation S wr, the steps are the same as those in step (1) of the steady-state method in the specific embodiment;

[0068] (2) Put the re-saturated core into the core holder, and pressurize the confining pressure pump to the in-situ effective stress P w = 82 MPa, adjust the front part of the heating device to the formation temperature T f = 120 °C, adjust the rear part of the heating device to the evaporation temperature T e = 240 °C, keep the inlet and outlet pressures constant during displacement, and record the outlet flow rate and the density of the outlet mixed gas at each moment;

[0069] (3) At 0.1 MPa and 240 °C, the density ρ ve of saturated water vapor is 0.4238 kg / m 3 , and the density ρ ge of nitrogen is 1.0338 kg / m 3 ; at 82 MPa and 120 °C, the density of saturated water vapor is ρ wf = 979.5357 kg / m 3 , and the density of nitrogen is ρ gf = 436.5304 kg / m 3 , substitute into formulas (13) - (17) to calculate the volume flow rates q f of the gas phase and the liquid phase of the core at the formation temperature T gf 、q wf , and finally substitute the recorded data into (18) - (24) to calculate the two-phase relative permeability of the core under the water saturation S w ' and the formation temperature T f .

[0070] Draw the gas-water relative permeability curve through the experimental results. The gas-water relative permeability curve of the relatively high-permeability core is as shown in Figure 1 , and the gas-water relative permeability curve of the relatively low-permeability core is as shown in Figure 2 .

Claims

1. A testing device for gas-water relative permeability of tight rocks under high temperature and high pressure, characterized in that, It includes a gas cylinder, a liquid pump, a throttle valve, a flowmeter, a thermometer, a pressure sensor, an intermediate container, a core holder, an confining pressure pump, a heating device, a gas densitometer, and a computer; The gas outlet of the gas cylinder and the liquid outlet of the liquid pump are respectively connected to corresponding inlet flowmeters. Heating devices are arranged for both the two inlet flowmeters, the core holder, and the pipelines therebetween. The core holder is provided with a pipeline connected to the confining pressure pump. The core holder is connected to the intermediate container and the pressure sensor on its left and right. An outlet flowmeter and a gas densitometer are arranged on the subsequent pipeline at the outlet of the core holder, and another set of heating devices are arranged thereon. Heat insulation materials are arranged between the two sets of heating devices; The heating device includes a high-temperature resistant double-layer cylinder, a heat insulation material, and a thermometer. The outside of the cylinder is wrapped with the heat insulation material, and the outside of the heat insulation material is covered with a shell. The inner layer of the cylinder is wound with a heating resistance wire; The heating device includes a high-temperature resistant double-layer cylinder. The double-layer cylinder has a certain toughness and can be bent to a certain extent along with the pipeline. The cylinder is a double-layer sandwich structure. The inner layer of the cylinder is wound with a heating resistance wire for heating, and the heating temperature can be adjusted by adjusting the resistance wire. The outer layer of the cylinder is wrapped with a heat insulation material for heat preservation, and the outside of the heat insulation material is covered with a shell; The fluid injection system of the device includes a gas injection system and a liquid injection system; the gas injection system includes a gas cylinder, which is sequentially connected with a voltage stabilizer, a constant current device, a valve, and a flowmeter at the back; the liquid injection system includes a liquid pump, a valve, and a flowmeter; The heating devices used are divided into two parts; with the outlet of the core holder as the boundary, the front part of the heating device is used to simulate the in-situ formation temperature, and the rear part of the heating device is used for fluid heating. Heat insulation materials are arranged at the interface between the two parts; A flowmeter and a gas densitometer are sequentially connected between the intermediate container and the outlet end of the pipeline; all the pressure sensors, gas densitometers, and flowmeters in the device are connected to the computer; According to the permeability of the experimental core, a suitable gas-water relative permeability measurement method can be selected, and then the experimental mode of the device can be changed. If the core permeability ≥ 1 mD, the steady-state method is used to carry out the gas-water relative permeability test experiment; if the core permeability < 1 mD, the non-steady-state method is used to carry out the gas-water relative permeability test experiment.

2. A method for testing the gas-water relative permeability of tight rocks under high temperature and high pressure, which is implemented by using the testing device described in claim 1, and is characterized in that, The steps of the steady-state method adopted in the experiment include: Step 1, before the experiment, the core sample needs to be fully washed with oil, washed with salt, and dried. Measure the core length L, diameter D, and dry weight m0 of the core, and calculate the core cross-sectional area A; use the pressure pulse decay method to measure the core permeability K0, and use the vacuum pressurization and water saturation method to measure the core porosity φ0; Step 2: At the beginning of the experiment, all valves in the device are default closed. Place the core saturated with the experimental liquid into the core holder, and pressurize the confining pressure pump to the in-situ effective stress P w ; Step 3: Open the gas cylinder, open the control valve of the gas injection system, open the left and right valves of the core holder, and adjust the two heating devices to the formation temperature T f ; Step 4: Start displacing the core to establish the irreducible water saturation. After the inlet and outlet flow rates become stable, record the current time, the irreducible water saturation S wr and the formation temperature T f and the experimental gas flow rate q at the outlet under the conditions of g (S wr ), the inlet and outlet pressures p1(S wr ) and p2; Close all experimental devices, take out the core, and record the core mass m1 at this time; Calculate the volume V of the displaced liquid w0 and the irreducible water saturation S of the core wr ; Calculate the effective gas permeability K wr of the core under the conditions of the irreducible water saturation S f and the formation temperature T g (S wr ) and the relative gas permeability K rg (S wr ): p2 = p a where, V w0 is the volume of the expelled liquid, cm 3 ; m0 is the dry weight of the core, g; m1 is the mass of the core after establishing the irreducible water saturation, g; ρ0 is the density of the experimental liquid at room temperature, g / cm 3 ; S wr is the irreducible water saturation, %; V p is the pore volume, cm 3 ; p1(S wr ) and p2 are the inlet and outlet pressures under the conditions of irreducible water saturation S wr and formation temperature T f , where p2 is equal to the atmospheric pressure, MPa; p a is the atmospheric pressure, MPa; q g (S wr ) is the experimental gas flow rate at the outlet under the conditions of irreducible water saturation S wr and formation temperature T f , cm 3 / s; μ gf is the viscosity of the experimental gas at formation temperature T f , mPa·s; L is the core length, cm; A is the cross-sectional area of the core, cm 2 ; K g (S wr ) and K rg (S wr ) are the effective gas permeability and relative gas permeability of the core under the conditions of irreducible water saturation S wr and formation temperature T f , mD; K0 is the initial permeability of the core, mD; Step 5: Place the core with established irreducible water saturation into the holder, and pressurize the confining pressure pump to the in-situ effective stress P w , open the gas cylinder, open the control valve of the gas injection system, open the left and right valves of the core holder, open the control valve of the liquid injection system, turn on the liquid pump, and adjust the front heating device to the formation temperature T f ; Step 6: Inject gas and liquid into the rock sample at a proportional flow rate through the gas-liquid injection system. After the flow rate stabilizes, record the current time, the water saturation S w and the formation temperature T f under the conditions of the inlet and outlet pressures p1(S w ) and p2, and the flowmeter readings q g (S w ) and q w (S w ); Calculate the water saturation S of the core at the current time w ; Calculate the two-phase effective permeability K w of the core at the current time under the conditions of water saturation S f and formation temperature T g (S w ), K w (S w ), and the two-phase relative permeability K f of the core under the formation temperature T rg (S w ), K rw (S w ): Among them, S w is the water saturation of the core under the current injection gas-liquid flow rate ratio, %; q g (S w ) and q w (S w ) are the gas and water outlet flow rates at the water saturation S w and formation temperature T f , cm 3 / s; μ wf is the viscosity of the liquid at the formation temperature T f , mPa·s; p1(S w ) is the inlet pressure under the conditions of water saturation S w and formation temperature T f , MPa; K g (S w ) and K w (S w ) are the effective gas and liquid permeabilities of the core under the conditions of water saturation S w and formation temperature T f , mD; K rg (S w ) and K rw (S w ) are the relative gas and liquid permeabilities of the core under the conditions of water saturation S w and formation temperature T f , mD; Step 7, reduce the gas / liquid flow ratio injected into the core sample to increase the water saturation of the core, and repeat Step 6 for the remaining steps until the gas / liquid flow ratio is equal to 0, and then end the experiment.

3. A method for testing the gas-water relative permeability of tight rocks under high temperature and high pressure, which is implemented by using the testing device described in claim 1, characterized in that, The steps of the non-steady-state method adopted in the experiment include: Step 1, before the experiment, the core sample needs to be fully washed with oil, washed with salt, and dried. Measure the core length L, diameter D, and dry weight m0 of the core, and calculate the core cross-sectional area A; use the pressure pulse decay method to measure the core permeability K0, and use the vacuum pressurization and water saturation method to measure the core porosity φ0; Step 2: At the beginning of the experiment, all valves in the device are default closed. Place the core saturated with the experimental liquid into the core holder, and pressurize the confining pressure pump to the in-situ effective stress P w ; Step 3: Open the gas cylinder, open the control valve of the gas injection system, open the left and right valves of the core holder, and adjust the two heating devices to the formation temperature T f ; Step 4: Start displacing the core to establish the irreducible water saturation. After the inlet and outlet flow rates become stable, close all the experimental devices, take out the core, and record the core mass m1 at this time; calculate the volume V of the displaced liquid w0 , the irreducible water saturation S of the core wr ; Step 5: Re-saturate the core with the experimental liquid and then place it in the core holder. Pressurize the confining pressure pump to the in-situ effective stress P w ; Adjust the front part of the heating device to the formation temperature T f , and adjust the rear part of the heating device to the evaporation temperature T e , which is determined by the evaporation properties of the experimental injection fluid, to ensure that the fluid evaporates instantaneously when it enters the outlet pipeline of the core holder; Step 6: Open the gas cylinder, open the control valve of the gas injection system, open the left and right valves of the core holder, start gas flooding, keep the inlet and outlet pressures constant during flooding, and record the outlet flow rate q e and the density ρ e of the outlet mixed gas at each moment; Step 7, calculate the evaporation temperature T e The volume fractions s g of the experimental gas and water vapor v , and then calculate the evaporation temperature T e The flow rates of the experimental gas and water vapor under q ge = q e · s g q ve = q e · s v where s g and s v are the volume fractions of the experimental gas and water vapor at the evaporation temperature T e , %, respectively; ρ ge and ρ ve are the densities of the experimental gas and water vapor at T e temperature, g / cm 3 ; q ge and q ve are the flow rates of the experimental gas and water vapor at T e temperature, mL / s, respectively; Step 8, calculate the formation temperature T f of the gas and liquid volume flow rate q gf , q wf : q gf ρ gf = q ge ρ ge where ρ gf and ρ wf are the densities of the experimental gas and water at temperature T f , g / cm 3 ; a f is the ratio of the volume of the solution to the volume of the solvent in the experimental liquid per unit volume at temperature T f ; Step 9, calculate the two-phase relative permeabilities K w ' and K f ' at the water saturation S rg ' and the formation temperature T rw ': where f g (S w ′) is the gas holdup in the outlet fluid per unit time, %; is the cumulative gas production volume, mL; is the cumulative outlet flow rate, mL; I is the flow capacity ratio; K rg ′ and K rw ′ are the relative permeabilities of gas and liquid phases of the core under the water saturation S w ′ and the formation temperature T f conditions, mD; Step 10, turn off all heating devices, clean the pipeline, and end the experiment.

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