A reservoir injectivity test device and method

Abstract

The present application relates to the technical field of gas injection construction of oil and gas wells, and more particularly to a production layer injection capacity testing device and method, which comprises, in sequence, a gas source, a gas booster system, a high-pressure storage tank, a buffer tank, a K-type flowmeter, a three-axis core holder, a pressure relief valve and a sampling device, and further comprises a constant-speed constant-pressure pump, a temperature control system, a ground stress simulation system, a back pressure system and a pressure monitoring system, wherein the pressure monitoring system comprises a first pressure gauge, a second pressure gauge, a third pressure gauge, a fourth pressure gauge and a pressure sensor; in the simulation of the gas injection process, the injection capacity of the core can be determined according to the data measured by the third pressure gauge, the pressure sensor and the K-type flowmeter; and by changing the parameters to simulate the injection process, different production layer injection capacities can be obtained; wherein the high-pressure storage tank can ensure that there is sufficient high-pressure gas during the experiment, and the buffer tank can avoid excessive fluctuations in the gas injection pressure during the experiment, thereby improving the completion quality and accuracy of the experiment.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of gas injection operation in oil and gas wells, and more particularly to a production layer injection capacity testing device and method. BACKGROUND

[0002] How to ensure energy security and effectively control carbon emissions is the top priority of the energy industry development. After years of research and practice, CO2 flooding and geological storage not only can effectively improve oil recovery, but also can realize in-situ geological storage of CO2 in the reservoir. Among them, the research on the injection capacity of the production layer can provide scientific basis for the next step of CO2 geological storage engineering. In order to effectively evaluate the injection capacity of the production layer, it is particularly important to develop an efficient testing device and method, however, there are problems in the development process that the laboratory scale cannot completely simulate the actual gas injection development.

[0003] The prior art discloses a CO2 displacement simulation test method, and the test device used includes: a model system for containing rock samples and applying pressure pulses, a gas control system for providing test gas to the model system, a temperature control system for controlling and maintaining the temperature of the model system, a triaxial loading system for applying confining pressure and axial pressure to the core holder in the model system, a vacuum pumping system for pumping the test device, a gas sample collection system for collecting and detecting the gas components after the test, and an electrical control and monitoring system. In this scheme, the pressure data in the upstream reference cylinder, the downstream reference cylinder and the core holder need to be collected to observe whether the pressure is stable; if the pressure is stable, the gas in the device is released, and the confining pressure is removed at the same time, if the pressure is not stable, repeat the step, in order to ensure the accuracy of the experiment, the experimental process is complicated; and if the pressure in the upstream reference cylinder decreases obviously during the test, that is, more than 5% of the test design inlet pressure, CO2 is supplemented to the upstream reference cylinder in time, the pressure fluctuation is large, and it is more difficult to ensure the accuracy of the experiment. SUMMARY

[0004] The purpose of the present application is to overcome the shortcomings of the prior art that it is difficult to ensure the accuracy of the experiment, and to provide a production layer injection capacity testing device and method, which can ensure sufficient high-pressure gas during the experimental process, avoid the decrease of experimental pressure caused by insufficient gas, and reduce pressure fluctuation, improve the completion quality of the experiment and the accuracy of the experiment.

[0005] To solve the above technical problems, the technical scheme adopted by the present application is:

[0006] The application provides a reservoir injection capacity testing device, which comprises a gas source, a gas pressurizing system, a high-pressure storage tank, a buffer tank, a Korsite flowmeter, a three-axis core holder, a pressure relief valve and a sampling device which are sequentially connected, further comprises a constant-speed constant-pressure pump, a temperature control system, a ground stress simulation system, a back pressure system and a pressure monitoring system, the constant-speed constant-pressure pump is communicated with the buffer tank, the temperature control system is connected with the three-axis core holder through a signal line and is provided with a temperature sensor, the ground stress simulation system is communicated with the three-axis core holder, the pressure relief valve is arranged between the three-axis core holder and the back pressure system, the pressure monitoring system comprises a first pressure gauge, a second pressure gauge, a third pressure gauge, a fourth pressure gauge and a pressure sensor, the first pressure gauge is arranged between the gas source and the gas pressurizing system, the second pressure gauge is arranged between the gas pressurizing system and the high-pressure storage tank, the third pressure gauge is arranged between the Korsite flowmeter and the three-axis core holder, the fourth pressure gauge is arranged between the ground stress simulation system and the three-axis core holder, and the pressure sensor is arranged between the three-axis core holder and the back pressure system.

[0007] The layer production injection capacity testing device of the application, during the experiment, the core is loaded into the triaxial core holder, the gas source can provide the simulated multi-component CO2 experimental gas, the gas pressurizing system and the constant speed and constant pressure pump can deliver the experimental gas to the triaxial core holder; the core in the triaxial core holder can simulate the injection channel of the production layer; the ground stress simulation system is used to simulate the ground stress, the fourth pressure gauge is used to accurately control the confining pressure of the triaxial core holder; the back pressure system is used to simulate the formation pressure, the pressure sensor can accurately control the back pressure; the temperature control system is used to simulate the formation temperature, the temperature sensor is used to monitor the temperature of the triaxial core holder in real time; so as to simulate the gas injection process; if the outlet pressure of the triaxial core holder is greater than the back pressure, the pressure relief valve is opened, the gas flows into the sampling device, and the liquid in the sampling device is discharged, so that the experiment is safe, and the volume of the discharged liquid is the volume of the outflowing gas; during the simulation of the gas injection process, the third pressure gauge, the pressure sensor and the orifice flowmeter can measure the pressure at both ends of the triaxial core holder and the gas flow through the triaxial core holder, the injection capacity of the core can be determined according to the measured data, the injection process is simulated by changing the core permeability, the injected gas component, the formation pressure, the formation temperature, the injection pressure difference and other parameters, different production layer injection capacities can be obtained, and thus the change rule of the production layer injection capacity can be obtained; wherein the gas pressurizing system pressurizes the experimental gas provided by the gas source, the first pressure gauge is used to monitor the pressure of the gas source in real time, the pressurized gas enters the high-pressure storage tank, the second pressure gauge is used to monitor the pressure of the gas in the high-pressure storage tank, and then flows into the buffer tank, the constant speed and constant pressure pump is used to displace the injected gas, the high-pressure storage tank can ensure that there is sufficient high-pressure gas during the experiment, avoids the decrease of the experimental pressure due to the insufficient gas amount, improves the completion quality of the experiment, and the buffer tank can avoid the excessive fluctuation of the gas injection pressure during the experiment, and reduces the experimental error.

[0008] Further, a first control valve is arranged between the first pressure gauge and the gas pressurizing system, a second control valve is arranged between the high-pressure storage tank and the buffer tank, a third control valve is arranged between the buffer tank and the orifice flowmeter, and a fourth control valve is arranged between the triaxial core holder and the pressure relief valve.

[0009] Further, a first vent valve is arranged between the high-pressure storage tank and the second control valve, a second vent valve is arranged between the buffer tank and the third control valve, and a third vent valve is arranged between the fourth control valve and the pressure relief valve.

[0010] Further, one end of the ground stress simulation system is communicated with the first hydraulic oil storage tank through a fifth control valve, and the other end of the ground stress simulation system is communicated with the fourth pressure gauge through a sixth control valve.

[0011] Further, one end of the back pressure system is communicated with the second hydraulic oil storage tank through the seventh control valve, and the other end of the back pressure system is communicated with the pressure sensor through the eighth control valve.

[0012] Further, the gas source is provided with a safety valve.

[0013] Further, the constant speed and constant pressure pump is connected with a water storage container.

[0014] Further, the computer device is further included, and the orifice flowmeter, the third pressure gauge, the pressure sensor, the temperature control system and the constant speed and constant pressure pump are respectively in communication connection with the computer device.

[0015] The present application further provides a production layer injection capacity testing method, comprising the following steps:

[0016] S1: collecting core parameters and gas source gas parameters, connecting the production layer injection capacity testing device, and checking the sealing of the pipeline;

[0017] S2: heating the triaxial core holder to a specified temperature through the temperature control system, adding confining pressure to a specified confining pressure through the ground stress simulation system, and adding back pressure to a specified back pressure through the back pressure system;

[0018] S3: filling gas into the gas booster system through the gas source, boosting the gas to the high-pressure storage tank through the gas booster system, and injecting high-pressure gas into the buffer tank;

[0019] S4: displacing the gas in the buffer tank to the core through the constant speed and constant pressure pump to simulate the gas injection process, and recording experimental data after the pressure of the constant speed and constant pressure pump is stable;

[0020] S5: turning off the temperature control system, cooling the triaxial core holder to room temperature, disassembling the injection pipeline, unloading the confining pressure and the back pressure, emptying the system gas to the outdoor, taking out the rock sample, and ending the experiment;

[0021] S6: calculating the core injection index to represent the production layer injection capacity.

[0022] The production layer injection capacity testing method of the present application can simulate the formation environment to perform gas injection simulation, boost and deliver the experimental gas through the gas source and the gas booster system, use the high-pressure storage tank to ensure sufficient experimental gas, use the buffer tank to reduce gas injection fluctuation, improve experimental completion quality, and reduce experimental error; by changing core permeability, injected gas composition, formation pressure, formation temperature, injection pressure difference and other parameters to simulate the injection process, different production layer injection capacities can be obtained, so that the change rule of the production layer injection capacity can be obtained.

[0023] Preferably, in step S6, the evaluation of the size of the formation injection capacity uses injection index to judge, the injection index is the fluid injection amount under unit cross section and unit pressure difference, the injection index is calculated by recording injection speed, cross section area and injection pressure difference, the calculation formula is:

[0024]

[0025] In the formula, I represents injection index, Q represents injection speed, A represents cross section area, ΔP represents injection pressure difference,

[0026] Compared with the prior art, the formation injection capacity testing device and method of the present application has the following beneficial effects:

[0027] 1. In the simulation of the gas injection process, the pressure at both ends of the triaxial core holder and the gas flow through the triaxial core holder can be measured by the third pressure gauge, the pressure sensor and the orifice flowmeter, and the formation injection capacity can be calculated;

[0028] 2. The high-pressure storage tank can ensure sufficient high-pressure experimental gas, so as to avoid the decrease of experimental pressure due to insufficient gas amount and improve the completion quality of the experiment;

[0029] 3. The buffer tank can avoid the excessive fluctuation of the gas injection pressure during the experiment, reduce the experimental error and improve the accuracy of the experiment. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 Fig. 1 is a structural schematic view of the formation injection capacity testing device in the first embodiment of the present application;

[0031] Figure 2 Fig. 2 is a structural schematic view of the formation injection capacity testing device in the second embodiment of the present application;

[0032] Figure 3 Fig. 3 is a flow chart of the formation injection capacity testing method in the third embodiment of the present application.

[0033] In the drawing: 1-gas source; 2-gas pressurizing system; 3-high pressure storage tank; 4-buffer tank; 5-constant speed and constant pressure pump; 6-constant flow meter; 7-three-axis core holder; 8-ground stress simulation system; 9-back pressure system; 10-temperature control system; 11-temperature sensor; 12-pressure relief valve; 13-sampling device; 14-first pressure gauge; 15-second pressure gauge; 16-third pressure gauge; 17-fourth pressure gauge; 18-pressure sensor; 19-first control valve; 20-second control valve; 21-third control valve; 22-fourth control valve; 23-fifth control valve; 24-sixth control valve; 25-seventh control valve; 26-eighth control valve; 27-first vent valve; 28-second vent valve; 29-third vent valve; 30-water storage container; 31-first hydraulic oil storage tank; 32-second hydraulic oil storage tank; 33-computer equipment. DETAILED DESCRIPTION

[0034] The application will be further described below in connection with the specific embodiments. The drawings are only used for illustrative description, and the representation is only a schematic diagram, not a physical diagram, and should not be understood as a limitation of the patent; in order to better illustrate the embodiments of the application, some components of the drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0035] The same or similar reference numerals in the drawings of the embodiments of the application correspond to the same or similar components; in the description of the application, it should be understood that if the terms "upper", "lower", "left", "right" and the like indicate the orientation or positional relationship shown in the drawings, only for the convenience of describing the application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, therefore the positional relationship described in the drawings is only used for illustrative description, and should not be understood as a limitation of the patent, for those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0036] Embodiment one

[0037] This embodiment is the first embodiment of the pay zone injection capacity testing device, as shown in Figure 1As shown, including the gas source 1, gas booster system 2, high pressure tank 3, buffer tank 4, gas flow meter 6, triaxial core holder 7, pressure relief valve 12 and sampling device 13, also including constant speed constant pressure pump 5, temperature control system 10, ground stress simulation system 8, back pressure system 9 and pressure monitoring system, constant speed constant pressure pump 5 and buffer tank 4 communication, temperature control system 10 and triaxial core holder 7 through the signal line is connected with temperature sensor 11, ground stress simulation system 8 and triaxial core holder 7 communication, pressure relief valve 12 is located between triaxial core holder 7 and back pressure system 9, pressure monitoring system includes first pressure gauge 14, second pressure gauge 15, third pressure gauge 16, fourth pressure gauge 17 and pressure sensor 18, first pressure gauge 14 is located between gas source 1 and gas booster system 2, second pressure gauge 15 is located between gas booster system 2 and high pressure tank 3, third pressure gauge 16 is located between gas flow meter 6 and triaxial core holder 7, fourth pressure gauge 17 is located between ground stress simulation system 8 and triaxial core holder 7, pressure sensor 18 is located between triaxial core holder 7 and back pressure system 9.

[0038] The above-mentioned production layer injection capacity testing device, during the experiment, the core is loaded into the triaxial core holder 7, the gas source 1 can provide the simulated multi-component CO2 experimental gas, the gas pressurizing system 2 and the constant-speed constant-pressure pump 5 can deliver the experimental gas to the triaxial core holder 7; the core in the triaxial core holder 7 can simulate the injection channel of the production layer; the ground stress simulation system 8 is used for simulating the ground stress, and the fourth pressure gauge 17 is used for accurately regulating the confining pressure of the triaxial core holder 7; the back pressure system 9 is used for simulating the formation pressure, and the pressure sensor 18 can accurately control the back pressure; the temperature control system 10 is used for simulating the formation temperature, and the temperature sensor 11 is used for real-time monitoring of the temperature of the triaxial core holder 7; so as to simulate the gas injection process; if the outlet pressure of the triaxial core holder 7 is greater than the back pressure, the pressure relief valve 12 is opened, the gas flows into the sampling device 13, and the liquid in the sampling device 13 is discharged, so that the experiment is safe, and the volume of the discharged liquid is the volume of the outflowing gas; during the simulation of the gas injection process, the third pressure gauge 16, the pressure sensor 18 and the orifice flowmeter 6 can measure the pressure at both ends of the triaxial core holder 7 and the gas flow through the triaxial core holder 7, the injection capacity of the core can be determined according to the measured data, the injection process is simulated by changing the core permeability, the injected gas component, the formation pressure, the formation temperature, the injection pressure difference and other parameters, different production layer injection capacities can be obtained, and thus the change rule of the production layer injection capacity can be obtained; wherein the gas pressurizing system 2 pressurizes the experimental gas provided by the gas source 1, the first pressure gauge 14 is used for real-time monitoring of the pressure of the gas source 1, the pressurized gas enters the high-pressure storage tank 3, the second pressure gauge 15 is used for monitoring the pressure of the gas in the high-pressure storage tank 3, and then flows into the buffer tank 4, the constant-speed constant-pressure pump 5 is used for displacement injection, the high-pressure storage tank 3 can ensure that there is sufficient high-pressure gas during the experiment, so as to avoid the decrease of the experimental pressure due to insufficient gas amount, and improve the completion quality of the experiment, and the buffer tank 4 can avoid that the injection pressure of the gas fluctuates too much during the experiment, and reduces the experimental error.

[0039] As shown in Figure 1 The first control valve 19 is arranged between the first pressure gauge 14 and the gas pressurizing system 2, the second control valve 20 is arranged between the high-pressure storage tank 3 and the buffer tank 4, the third control valve 21 is arranged between the buffer tank 4 and the orifice flowmeter 6, and the fourth control valve 22 is arranged between the triaxial core holder 7 and the pressure relief valve 12. The opening and closing of the first control valve 19, the second control valve 20, the third control valve 21 and the fourth control valve 22 can control the flow state of the gas. Specifically, the first control valve 19 can control the flow of the gas from the gas source 1 to the gas pressurizing system 2, the second control valve 20 can control the flow of the gas from the high-pressure storage tank 3 to the buffer tank 4, the third control valve 21 can control the flow of the gas from the buffer tank 4 to the triaxial core holder 7, and the fourth control valve 22 can control the flow of the gas from the triaxial core holder 7 to the sampling device 13.

[0040] As shown in Figure 1As shown, the high-pressure tank 3 is provided with a first vent valve 27 between the second control valve 20, the buffer tank 4 is provided with a second vent valve 28 between the third control valve 21, and the fourth control valve 22 is provided with a third vent valve 29 between the pressure relief valve 12. The first vent valve 27 is used to discharge the residual gas in the high-pressure tank 3 and the pipeline after the experiment is completed, the second vent valve 28 is used to discharge the residual gas in the buffer tank 4 and the pipeline after the experiment is completed, and the third vent valve 29 is used to vent the residual gas in the triaxial core holder 7 and the pipeline.

[0041] The core holder is divided into an inner ring and an outer ring by a rubber seal; the inner ring is used to place the core sample, simulate the injection channel of the production layer, and the inner ring is an independent pore environment; the outer ring is used to inject hydraulic oil, the confining pressure is applied through the geostress simulation system 8, the average absolute geostress is simulated, and the temperature of the hydraulic oil is controlled through the temperature control system 10 to set the experimental temperature. The use of hydraulic oil heating can ensure uniform heating of the triaxial core holder 7, thereby ensuring the accuracy of the experiment, and the hydraulic oil also has a good corrosion protection effect on the triaxial core holder 7.

[0042] As shown in Figure 1 One end of the geostress simulation system 8 is communicated with the first hydraulic oil tank 31 through the fifth control valve 23, and the other end of the geostress simulation system 8 is communicated with the fourth pressure gauge 17 through the sixth control valve 24; one end of the back pressure system 9 is communicated with the second hydraulic oil tank 32 through the seventh control valve 25, and the other end of the back pressure system 9 is communicated with the pressure sensor 18 through the eighth control valve 26. The flow of the hydraulic oil is controlled through the fifth control valve 23, the sixth control valve 24, the seventh control valve 25 and the eighth control valve 26, and the pressure is monitored through the fourth pressure gauge 17 and the pressure sensor 18 respectively.

[0043] The gas source 1 is provided with a safety valve to ensure the safety of the experiment.

[0044] The gas source 1 adopts a standard gas cylinder, and the single-component gas and the multi-component gas are standard gases after configuration, so as to ensure the standard of the gas source 1 and avoid the influence of the gas component content on the experiment.

[0045] The gas booster system 2 is provided with a gas booster, an air compressor, an air dryer, a booster controller, a gas concentration monitoring and alarm system, and a gas pressure reducer, which can accurately pressurize the gas during the experiment, monitor the concentration of the experimental gas in the air at any time, improve the accuracy of the experiment and ensure the safety of the experiment.

[0046] As shown in Figure 1 The constant-speed constant-pressure pump 5 is connected with a water storage container 30 for providing water required for the displacement gas.

[0047] The constant speed and constant pressure pump 5 is provided with a first control panel, which can control the injection parameters in real time during the experiment; the third pressure gauge 16 can form a control loop with the constant speed and constant pressure pump 5 to realize the control of the working pressure; if the pressure measured by the third pressure gauge 16 is greater than the set working pressure, the pressure can be adjusted through the constant speed and constant pressure pump 5 until the pressure measured by the third pressure gauge 16 is not greater than the set working pressure.

[0048] The temperature control system 10 is provided with a second control panel, which can control the temperature of the three-axis core holder 7 to simulate different formation temperatures.

[0049] Specifically, the maximum working pressure of the gas pressurizing system 2 is set to 60 MPa; the volume of the high-pressure storage tank 3 is 6 L; the volume of the buffer tank 4 is 3 L, and the design pressure is 100 MPa, which ensures that the experiment has sufficient high-pressure gas; the design size of the core sample of the three-axis core holder 7 is 1 inch, the length of the core sample is 50 mm to 100 mm, the design pressure is 20 MPa, the design temperature is 100℃, and the highest simulated geostress of the geostress simulation system 8 is 60 MPa.

[0050] The reservoir injection capacity testing device of the embodiment is used to simulate the gas injection process of an offshore gas field, the permeability of the core sample is 1 mD, the gas source 1 is a multi-component gas containing CO2, N2 and CH4, the injection pressure of the simulated reservoir is 15.2 MPa, the temperature of the simulated reservoir is 60, and the pressure of the simulated reservoir is 15 MPa. The simulation experiment shows that when the injection is in a supercritical state, the higher the CO2 content in the component, the lower the viscosity of the multi-component CO2 fluid, the stronger the fluid flowability, and the stronger the reservoir injection capacity. The experimental results provide good support for the optimization of the gas injection process of the offshore gas field.

[0051] Embodiment Two

[0052] The second embodiment of the reservoir injection capacity testing device is similar to the first embodiment, and the difference is that, as shown in FIG. 2, the second embodiment is provided with a temperature control system 10, which can control the temperature of the three-axis core holder 7 to simulate different formation temperatures. Figure 2As shown, it also includes a computer device 33, a coriolis flowmeter 6, a third pressure gauge 16, a pressure sensor 18, a temperature control system 10, a constant-speed constant-pressure pump 5, which are respectively in communication connection with the computer device 33. Specifically, the pressure sensor 18 monitors the pressure at the outlet end of the triaxial core holder 7, and after conversion into a standard signal by a pressure transmitter, the standard signal is sent to the computer device 33; the coriolis flowmeter 6 has the ability to monitor the flow, and can output the gas flow under standard conditions, such as detecting the gas flow by the coriolis flowmeter 6, converting the gas flow under standard conditions by a flow transmitter, and sending the gas flow to the computer device 33; the temperature sensor 11 detects the temperature of the liquid in the annulus of the triaxial core holder 7, and after conversion into a standard signal by a temperature transmitter, the standard signal is sent to the computer device 33, and the computer device 33 automatically calculates the injection capacity of the production layer.

[0053] In this embodiment, the computer device 33 can remotely control the constant-speed constant-pressure pump 5 and the temperature control system 10, and can monitor the changes in pressure and flow in real time, obtain the change curve of pressure and flow, greatly improve the experimental efficiency and safety, and reduce the experimental risk.

[0054] Embodiment Three

[0055] This embodiment is the first embodiment of the injection capacity test method of the production layer, as shown in Figure 3 , including the following steps:

[0056] S1: Collecting core parameters and gas source 1 gas parameters, connecting the injection capacity test device of embodiment one or embodiment two, and checking the sealing of the pipeline;

[0057] S2: Heating the triaxial core holder 7 to a specified temperature by the temperature control system 10, adding confining pressure to a specified confining pressure by the ground stress simulation system 8, and adding back pressure to a specified back pressure by the back pressure system 9;

[0058] S3: Filling gas into the gas booster system 2 by the gas source 1, and boosting the gas to the high-pressure storage tank 3 by the gas booster system 2 and injecting high-pressure gas into the buffer tank 4;

[0059] S4: Displacing the gas in the buffer tank 4 to the core by the constant-speed constant-pressure pump 5 to simulate the gas injection process, and recording experimental data after the pressure of the constant-speed constant-pressure pump 5 is stable;

[0060] S5: Turning off the temperature control system 10, and after the triaxial core holder 7 is cooled to room temperature, disassembling the injection pipeline, unloading the confining pressure and the back pressure, venting the system gas to the outdoor, taking out the rock sample, and ending the experiment;

[0061] S6: Calculating the core injection index to represent the injection capacity of the production layer.

[0062] The above-mentioned production layer injection capacity testing method can simulate formation environment to perform gas injection simulation, and through the gas source 1 and the gas pressurization system 2, the experimental gas is pressurized and delivered, the high-pressure storage tank 3 can ensure sufficient experimental gas, the buffer tank 4 can reduce the gas injection fluctuation, improve the experimental completion quality, and reduce the experimental error; by changing the core permeability, the injected gas component, the formation pressure, the formation temperature, the injection differential pressure and other parameters to simulate the injection process, different production layer injection capacities can be obtained, so that the change rule of the production layer injection capacity can be obtained.

[0063] In step S1, before the gas injection simulation process is performed, experimental design and sample preparation can be performed, the experimental design includes designing injection conditions, core rotation, ground stress conditions, gas source 1 selection, parallel experiments, production layer injection capacity analysis purposes and the like according to the characteristics of offshore gas reservoirs.

[0064] In step S2, in order to prevent the occurrence of channeling phenomenon during the experiment, the confining pressure is generally 6 MPa greater than the injection pressure.

[0065] The specific process of step S3 is as follows: open the gas cylinder valve of the gas source 1, charge 3 MPa to 5 MPa into the gas pressurization system 2, open the gas concentration monitoring and alarm system, adjust the pressurization pointer to the design value, slowly open the pressurization valve switch, after the pressurization is completed, the gas in the high-pressure storage tank 3 is injected into the buffer tank 4.

[0066] The specific process of step S4 is as follows: open the liquid injection switch of the constant-speed constant-pressure pump 5, displace the gas in the buffer tank 4 to the core, after the pressure of the constant-speed constant-pressure pump 5 is stabilized, read the data of the third pressure gauge 16, and record the data of the pressure sensor 18 and the orifice flowmeter 6.

[0067] In step S6, the evaluation of the size of the production layer injection capacity uses injection index to judge, the injection index is the fluid injection amount under unit cross-sectional area and unit differential pressure, the larger the injection index is, the better the injectivity is, and vice versa; the injection index is calculated by recording the injection speed, the cross-sectional area and the injection differential pressure, and the calculation formula is as follows:

[0068]

[0069] In the formula, I represents the injection index, Q represents the injection speed, A represents the cross-sectional area, and ΔP represents the injection differential pressure.

[0070] In the specific content of the above-mentioned specific embodiments, any non-contradictory combination of technical features can be performed, in order to make the description simple, all possible combinations of the above-mentioned technical features are not described, however, as long as the combination of these technical features does not exist contradiction, it should be considered as the scope recorded in the description.

[0071] Obviously, the above embodiments of the present application are merely exemplary but not intended to limit the embodiments of the present application. Based on the above description, any other variations or changes can be made by those skilled in the art without departing from the spirit and principles of the present application. It is not necessary to list all the embodiments here. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present application should be included in the protection scope of the claims of the present application.

Claims

1. A zone injectivity test apparatus, comprising: The utility model relates to a kind of triaxial gas injection experimental device, including sequentially connected gas source (1), gas booster system (2), high-pressure tank (3), buffer tank (4), orifice flowmeter (6), triaxial core holder (7), pressure relief valve (12) and sampling device (13), still including constant-speed constant-pressure pump (5), temperature control system (10), ground stress simulation system (8), back pressure system (9) and pressure monitoring system, the constant-speed constant-pressure pump (5) with the buffer tank (4) communication, the temperature control system (10) with triaxial core holder (7) is connected with temperature sensor (11) by signal line, the ground stress simulation system (8) with triaxial core holder (7) communication, the pressure relief valve (12) is located between triaxial core holder (7) and the back pressure system (9), the pressure monitoring system includes first pressure gauge (14), second pressure gauge (15), third pressure gauge (16), fourth pressure gauge (17) and pressure sensor (18), the first pressure gauge (14) is located between the gas source (1) and the gas booster system (2), the second pressure gauge (15) is located between the gas booster system (2) and the high-pressure tank (3), the third pressure gauge (16) is located between orifice flowmeter (6) and triaxial core holder (7), the fourth pressure gauge (17) is located between the ground stress simulation system (8) and triaxial core holder (7), the pressure sensor (18) is located between triaxial core holder (7) and the back pressure system (9); In use, triaxial core holder (7) is heated to specified temperature by temperature control system (10), confining pressure is added to specified confining pressure by ground stress simulation system (8), back pressure is added to specified back pressure by back pressure system (9);Gas is filled into gas booster system (2) by gas source (1), and high-pressure tank (3) is pressurized by gas booster system (2) and high-pressure gas is injected into buffer tank (4);Gas in buffer tank (4) is displaced into core by constant-speed constant-pressure pump (5) to simulate gas injection process, and experimental data is recorded after pressure of constant-speed constant-pressure pump (5) is stabilized.

2. The zonal injectivity test device of claim 1, wherein, First control valve (19) is arranged between the first pressure gauge (14) and the gas booster system (2), second control valve (20) is arranged between the high-pressure tank (3) and the buffer tank (4), third control valve (21) is arranged between the buffer tank (4) and orifice flowmeter (6), and fourth control valve (22) is arranged between triaxial core holder (7) and the pressure relief valve (12).

3. The zonal injectivity test apparatus of claim 2, wherein, First vent valve (27) is arranged between the high-pressure tank (3) and the second control valve (20), second vent valve (28) is arranged between the buffer tank (4) and third control valve (21), and third vent valve (29) is arranged between the fourth control valve (22) and the pressure relief valve (12).

4. The zonal injectivity test apparatus of claim 1, wherein, One end of the geostress simulation system (8) is communicated with the first hydraulic oil storage tank (31) through the fifth control valve (23), and the other end of the geostress simulation system (8) is communicated with the fourth pressure gauge (17) through the sixth control valve (24).

5. The zonal injectivity test device of claim 1, wherein, One end of the back pressure system (9) is communicated with the second hydraulic oil storage tank (32) through the seventh control valve (25), and the other end of the back pressure system (9) is communicated with the pressure sensor (18) through the eighth control valve (26).

6. The zonal injectivity test device of claim 1, wherein, The gas source (1) is provided with a safety valve.

7. The zonal injectivity test device of claim 1, wherein, The constant speed constant pressure pump (5) is connected with a water storage container (30).

8. The zonal injectivity test device of claim 1, wherein, Further comprising a computer device (33), the orifice flowmeter (6), the third pressure gauge (16), the pressure sensor (18), the temperature control system (10), the constant speed constant pressure pump (5) are respectively in communication connection with the computer device (33).

9. A method of testing a zone injectivity capacity, characterized by, The method comprises the following steps: S1: collect the core parameters and the gas source (1) gas parameters, connect the pay zone injection capacity testing device of any one of claims 1 to 8, check the sealing of the pipeline; S2: the triaxial core holder (7) is heated to a specified temperature by the temperature control system (10), the confining pressure is added to a specified confining pressure by the geostress simulation system (8), and the back pressure is added to a specified back pressure by the back pressure system (9); S3: the gas source (1) is filled into the gas booster system (2), and the gas booster system (2) is used to pressurize the gas into the high-pressure storage tank (3) and inject high-pressure gas into the buffer tank (4); S4: the gas in the buffer tank (4) is displaced into the core by the constant speed constant pressure pump (5) to simulate the gas injection process, and the experimental data is recorded after the pressure of the constant speed constant pressure pump (5) is stable; S5: turn off the temperature control system (10), and after the triaxial core holder (7) is cooled to room temperature, the injection pipeline is disassembled, the confining pressure and the back pressure are unloaded, the system gas is vented to the outdoor, the rock sample is taken out, and the experiment is ended; S6: calculate the core injection index to represent the pay zone injection capacity.

10. The zonal injectivity test method of claim 9, wherein, In step S6, the evaluation of the size of the pay zone injection capacity uses the injection index to judge, the injection index is the fluid injection amount under unit cross section and unit pressure difference, the injection index is calculated by recording the injection speed, cross section area and injection pressure difference, and the calculation formula is: ； wherein represents the injection index; represents the injection speed; represents the cross-sectional area; represents the injection pressure difference.

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