Fractured-vuggy gas reservoir overflow and well killing law evaluation device and application

Abstract

The invention provides a fracture-vug type gas reservoir overflow and well killing law evaluation device and application, and belongs to the field of petroleum and natural gas exploration. The device comprises a fractured-vuggy formation drilling simulation system, and a high-pressure gas injection system, which is connected with the fractured-vuggy formation drilling simulation system and is used for injecting gas into the fractured-vuggy formation drilling simulation system; the circulating liquid injection system is used for injecting circulating liquid into the fracture-cavity formation drilling simulation system; the cement injection system is used for injecting cement into the fracture-cavity type stratum drilling simulation system; and the measurement recording system is used for recording data. The device is closer to the real parameter change process of the overflow kill well of the fracture-vug type gas reservoir, and has the characteristics of continuous and real simulation, multi-condition coupling, measurable multi-parameter and visible process. Experimental measurement results obtained through the method can provide experimental simulation and data support for overflow type judgment and well killing method selection during fracture-vug type gas reservoir overflow.

Description

Technical Field

[0001] The invention belongs to the field of oil and natural gas exploration and development, and specifically relates to a device for evaluating overflow and well killing rules of fracture-cavity gas reservoirs and its application. Background Art

[0002] The current formation overflow and well killing physical simulation experimental device can simulate the overflow process or well killing process separately, realize visualization, and collect relevant parameters. The specific patents involved are as follows:

[0003] The Chinese patent publication "Multi-media Coupling Device for Formation Simulation Experiment" with publication number CN101949289B discloses a multi-media coupling device for formation simulation experiment, including a base, a support frame arranged on the base, a sealed material bin arranged on the support frame, a feed port arranged on the sealed material bin, an air inlet and a liquid inlet arranged on the side of the sealed material bin, and a driving device for driving the sealed material bin to rotate arranged on the support frame; the liquid inlet is connected to a liquid inlet system, the liquid inlet system includes a water pump, a water supply tank, a proportional regulating valve 1, a proportional regulating valve 2, an overflow valve and a water pipe installed at the liquid inlet; the air inlet is connected to an air inlet system, the air inlet system includes an air source, an air pump and an air pipe installed at the air inlet. It can adapt to the experimental requirements of formations with different inclination angles under sealed conditions.

[0004] The Chinese patent publication "A Test System for Wellbore Pressure Control Technology" with publication number CN202348183U discloses a test system for wellbore pressure control technology, including a formation simulation system, a drilling system, a simulated wellbore system and a wellbore pressure control system. The formation simulation system is composed of an auxiliary pump connected in sequence through a relief pressure regulating valve A, a stop valve A, a check valve, a relief pressure regulating valve B, and a stop valve B; pressure sensor A, pressure sensor B and pressure sensor C are respectively connected to the connection points of the auxiliary pump and the relief pressure regulating valve A, the check valve and the relief pressure regulating valve B, and the stop valve B and the simulated wellbore system. The wellbore structure of the simulated wellbore system is a single-layer casing with a parasitic pipe outside the casing; it can also be a double-layer casing, in which the bottom of the outer casing is a screen structure. The test system can simulate and detect changes in formation pressure, detect the accuracy of the acquisition and measurement system, and the reliability and repeatability of the control system, and play a certain guiding role in field tests and drilling technology services.

[0005] The Chinese patent publication "Simulation device for obtaining drilling parameters in controlled pressure drilling" with publication number CN103015973A discloses a simulation device for obtaining drilling parameters in controlled pressure drilling, including a simulated wellbore, a drilling fluid pipeline, a throttling pipeline, a leakage pipeline and an overflow pipeline; the simulated wellbore is provided with a throttling hole, a leakage hole and an overflow hole, and a drill string is fixed in the simulated wellbore; the drilling fluid pipeline is used to inject drilling fluid into the simulated wellbore, and a regulating valve and a flow transmitter are connected in series on the drilling fluid pipeline in sequence , pressure transmitter and drilling fluid mud pump; the throttling pipeline is used to make the drilling fluid in the simulated wellbore circulate normally, and the throttling pipeline is connected in series with the flow transmitter, pressure transmitter and high-pressure throttling valve in sequence; the leakage pipeline is used to make the drilling fluid in the simulated wellbore circulate in leakage, and the leakage pipeline is connected in series with the flow transmitter, pressure transmitter and regulating valve in sequence; the overflow pipeline is used to make the drilling fluid in the simulated wellbore overflow circulation, and the overflow pipeline is connected in series with the regulating valve, flow transmitter, pressure transmitter and overflow mud pump in sequence. It has a simple structure, low cost, reliable and practical.

[0006] The Chinese patent publication "Simulation device for obtaining drilling parameters in controlled pressure drilling, a visualization experimental device for simulating drilling overflow" with publication number CN204082125U discloses a visualization experimental device for simulating drilling overflow, which is mainly composed of an air compressor, a flow meter, a pressure-resistant plastic hose, a one-way valve, an aluminum alloy tee, a pressure gauge, a data acquisition system, a high-speed camera, a sink, a plastic hose, a plastic sealing cover, a plexiglass tube, and a sealing ring. The upper end of the plexiglass tube is connected to the plastic sealing cover, and a small hole is opened in the center of the plastic sealing cover. A plastic hose is connected to the small hole, and the end of the plastic hose is placed in the sink. The lower end of the plexiglass tube is connected to the aluminum alloy tee through a sealing ring, and one interface of the aluminum alloy tee is connected to a pressure gauge, and the other interface of the aluminum alloy tee is connected to the air compressor through a pressure-resistant plastic hose, and a flow meter and a one-way valve are installed on the pressure-resistant plastic hose. The plexiglass tube filled with a certain height of drilling fluid is injected with air by an air compressor to achieve the simulation of the drilling overflow process. The device has a simple structure, is easy to use, can realize accurate collection of experimental parameters, and has great value for promotion and application.

[0007] However, the above devices are unable to simulate the "overflow well-killing" process continuously, the data collected are of a single type, and none of them considers the effects of drill string rotation, formation cracks, size, shape and angle, and whether there is supplementation of formation pressure at the far end on the "overflow well-killing" process. They are unable to truly reflect the parameter change characteristics of different overflow types and different well-killing methods in carbonate fracture-vuggy oil and gas reservoirs. Summary of the invention

[0008] The purpose of the present invention is to solve the difficulties existing in the above-mentioned prior art, and to provide a device and application for evaluating the overflow and well-killing rules of fracture-cavity gas reservoirs, which can simulate the continuous process of different types of overflows and well-killing methods occurring in fracture-cavity gas reservoirs, and continuously collect various data of the "overflow and well-killing" process, so as to provide data guidance for the judgment of overflow types and the selection of well-killing methods of on-site fracture-cavity gas reservoirs, and can more realistically reflect the different overflow types and parameter characteristics of carbonate fracture-cavity oil and gas reservoirs.

[0009] The present invention is achieved through the following technical solutions:

[0010] The first aspect of the present invention provides a fracture-cavity gas reservoir overflow and well-killing law evaluation device, the device comprising: a fracture-cavity formation drilling simulation system, and respectively connected thereto:

[0011] High-pressure gas injection system, used to inject gas into the fracture-cavity formation drilling simulation system;

[0012] A circulating liquid injection system is used to inject circulating liquid into the fracture-cavity formation drilling simulation system;

[0013] Cement injection system, used to inject cement into the fracture-cavity formation drilling simulation system;

[0014] Measurement recording system, used to record data.

[0015] Preferably, the fracture-cavity formation drilling simulation system comprises: a high-pressure reactor, a motor, a drill string, a gate blowout preventer, a PDC drill bit, and a fracture simulation plate;

[0016] The high-pressure reactor comprises: a reactor body and a support frame; the support frame is arranged above the reactor body, and the motor is arranged at the bottom of the support frame;

[0017] The gate blowout preventer is arranged at the upper end of the kettle body;

[0018] The motor is connected to the upper end of the drill string, and the lower end of the drill string passes through the gate blowout preventer and is connected to the PDC drill bit located in the inner cavity of the kettle;

[0019] The crack simulation plate can be installed in the inner cavity of the kettle body;

[0020] A pressure conduction hole is opened on the lower wall of the kettle body, and the pressure conduction hole is connected to the high-pressure gas injection system.

[0021] Preferably, a drill string valve is provided at the upper end of the drill string, and a pressure gauge interface and a drilling fluid interface are provided on the drill string valve;

[0022] The first interface of the ram blowout preventer is connected to a pressure sensor;

[0023] The second interface of the ram blowout preventer is connected to a cement injection system and a circulating liquid injection system.

[0024] Preferably, the high-pressure gas injection system comprises: a constant-pressure gas tank, a gas cylinder, and a first booster pump;

[0025] The gas cylinder is connected to the first booster pump through a pipeline, the first booster pump is connected to the constant pressure gas tank through a pipeline, and the constant pressure gas tank is connected to the pressure conduction hole through a pipeline;

[0026] A valve is provided on the pipeline connecting the gas cylinder and the first booster pump;

[0027] A valve, a check valve, a valve, and a pressure sensor are sequentially arranged on the pipeline connecting the first booster pump and the constant pressure gas tank;

[0028] A valve is arranged on the pipeline connecting the constant pressure gas tank and the pressure conduction hole.

[0029] Preferably, the high-pressure gas injection system further comprises: an air compressor; the air compressor is connected to the first booster pump through a pipeline, and a one-way valve, a pressure gauge, and a valve are sequentially arranged on the pipeline.

[0030] Preferably, the circulating liquid injection system comprises: a first circulating pump, and a first anti-settling tank, a second anti-settling tank, and a third anti-settling tank respectively connected thereto; valves are respectively arranged on the pipelines connecting the first circulating pump and the first anti-settling tank, the second anti-settling tank, and the third anti-settling tank;

[0031] The first anti-settling tank, the second anti-settling tank and the third anti-settling tank are respectively connected to the back pressure valve through pipelines, and infrared liquid level monitors and valves are respectively arranged on the pipelines.

[0032] Preferably, a liquid-gas separator is also provided on the pipeline connecting the first anti-settling tank and the back pressure valve.

[0033] Preferably, the first circulation pump is connected to the second booster pump, and the second booster pump is connected to the drilling fluid interface on the drill string valve through a pipeline, and a valve is provided on the pipeline;

[0034] The back pressure valve is connected to the second interface on the gate blowout preventer.

[0035] Preferably, the back pressure valve is connected to the back pressure tracking pump via a pipeline, and a pressure sensor and a valve are provided on the pipeline.

[0036] Preferably, the cement injection system comprises an empty tank, a clean water tank, a cement ash tank and a mixing tank;

[0037] The empty tank, clean water tank and cement ash tank are connected to the mixing tank through pipelines, and valves are respectively provided on the pipelines;

[0038] The stirring tank is connected to the second circulation pump through a pipeline, and a valve is arranged on the pipeline;

[0039] The second circulation pump is connected to the back pressure valve through a pipeline, and a one-way valve and a valve are arranged on the pipeline.

[0040] A second aspect of the present invention provides a method for applying the above device, the method comprising:

[0041] The above device is used to simulate the following overflow well killing process:

[0042] For fractures of different scales and angles, when there is no pressure supplement at the far end, the overflow well-killing process is adopted when flat-push well-killing is used;

[0043] For fractures of different scales and angles, when there is no pressure supplement at the far end, the overflow well killing process when throttling circulation well killing is adopted;

[0044] For fractures of different scales and angles, when there is continuous pressure supplement at the far end, the overflow well-killing process of flat-push well-killing is adopted;

[0045] For fractures of different scales and angles, when there is continuous pressure replenishment at the far end, the overflow well-killing process during throttling circulation well-killing is adopted.

[0046] Compared with the prior art, the present invention has the following beneficial effects:

[0047] The present invention is closer to the actual parameter change process of fracture-cavity gas reservoir overflow and well killing, and has the characteristics of continuous simulation, multi-condition coupling, multi-parameter measurable, and process visualization. The experimental measurement results obtained by the present invention can provide experimental simulation and data support for overflow type judgment and well killing method selection during fracture-cavity gas reservoir overflow, and can help establish a more accurate fracture-cavity gas reservoir overflow and well killing simulation model, which has great application value in the field of safe and efficient exploration and development of carbonate fracture-cavity gas reservoirs. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 The present invention is a schematic diagram of the composition structure of a fracture-cavity gas reservoir overflow and well-killing law evaluation device.

[0049] Figure 1Among them, 1. high-pressure reactor; 2. motor; 3. drill string; 4. gate blowout preventer; 5. PDC drill bit; 6. fracture simulation board; 7. pressure detector; 8. pressure conduction hole; 9. constant pressure gas tank; 10. gas cylinder; 11. first booster pump; 12. air compressor; 13. first circulation pump; 14. first anti-settling tank (empty tank); 15. second anti-settling tank (well killing fluid tank); 16. third anti-settling tank (drilling fluid tank); 17. infrared liquid level monitor; 18. second booster pump; 19. back pressure tracking pump; 20. back pressure valve; 21. empty tank; 22. clean water tank; 23. cement ash tank; 24. mixing tank; 25. computer. Figure 1 The P in represents the pressure sensor. DETAILED DESCRIPTION

[0050] The present invention is further described in detail below in conjunction with the accompanying drawings:

[0051] like Figure 1 As shown, the present invention provides an overflow and well-killing law evaluation device for fracture-cavity gas reservoirs, the device comprising: a fracture-cavity formation drilling simulation system, and a high-pressure gas injection system, a circulating liquid injection system, a cement injection system, and a measurement and recording system respectively connected thereto. The high-pressure gas injection system is used to inject gas into the fracture-cavity formation drilling simulation system; the circulating liquid injection system is used to inject circulating liquid into the fracture-cavity formation drilling simulation system; the cement injection system is used to inject cement into the fracture-cavity formation drilling simulation system; and the measurement and recording system is used to record data. The present invention can simulate various types of overflow and well-killing processes of fracture-cavity gas reservoirs with different fracture scales, angles, constant volume type, continuous high pressure type, etc. through the independence and coordination between systems.

[0052] The embodiment of the device for evaluating overflow and well killing rules of fracture-cavity gas reservoirs of the present invention is as follows:

[0053] Embodiment 1:

[0054] The fracture-cavity formation drilling simulation system comprises: a high-pressure reactor 1, a motor 2, a drill string 3, a gate blowout preventer 4, a PDC drill bit 5, and a fracture simulation plate 6.

[0055] The high-pressure reactor 1 includes: a reactor body and a support frame. The support frame is arranged above the reactor body, and the motor 2 is arranged at the lower part of the support frame. The output shaft of the motor 2 is connected to the upper end of the drill string 3, and the lower end of the drill string 3 is connected to the PDC drill bit 5. The motor 2 can drive the drill string 3 and the PDC drill bit 5 to rotate. The gate blowout preventer 4 is arranged at the upper end of the reactor body, and the lower end of the drill string 3 passes through the gate blowout preventer 4 and enters the inner cavity of the reactor body. Preferably, a visual window is arranged on the reactor body.

[0056] A drill string valve is provided at the upper end of the drill string 3, and a pressure gauge interface and a drilling fluid interface are provided on the drill string valve. The pressure gauge interface is connected to a pressure sensor, and the pressure sensor is connected to a measurement and recording system.

[0057] The kettle body adopts the existing kettle body. The support frame can adopt the support frame of the existing reactor, which can support the motor and the drill string and press the kettle body at the same time. These are all existing structures and will not be described in detail here.

[0058] The first interface of the ram blowout preventer 4 is connected to a pressure sensor, and the pressure sensor is connected to a measurement and recording system. The second interface of the ram blowout preventer 4 is connected to a cement injection system and a circulating liquid injection system.

[0059] A pressure detector 7 is arranged at the bottom of the kettle body, and the pressure detector 7 is connected to the computer through a pressure sensor. A pressure conduction hole 8 is opened on the lower wall of the kettle body, and the pressure conduction hole 8 is connected to the high-pressure gas injection system.

[0060] The crack simulation plate 6 can be installed in the inner cavity of the kettle body. Specifically, the crack simulation plate 6 can be a resin sheet.

[0061] Embodiment 2:

[0062] The high-pressure gas injection system includes: a constant-pressure gas tank 9, a gas cylinder 10, and a first booster pump 11; the gas cylinder 10 is connected to the first booster pump 11 through a pipeline, the first booster pump 11 is connected to the constant-pressure gas tank 9 through a pipeline, and the constant-pressure gas tank 9 is connected to the pressure conduction hole 8 on the high-pressure reactor 1 through a pipeline. A valve is provided on the pipeline connecting the gas cylinder 10 and the first booster pump 11. A valve, a one-way valve, a valve, and a pressure sensor are sequentially provided on the pipeline connecting the first booster pump 11 and the constant-pressure gas tank 9. A valve is provided on the pipeline connecting the constant-pressure gas tank 9 and the pressure conduction hole 8.

[0063] The high-pressure gas injection system further includes: an air compressor 12; the air compressor 12 is connected to the first booster pump 11 through a pipeline, and a one-way valve, a pressure gauge, and a valve are sequentially arranged on the pipeline connecting the air compressor 12 and the first booster pump 11.

[0064] The gas in the gas cylinder 10 (the pressure in the gas cylinder may be greater than the atmospheric pressure) is compressed by the first booster pump 11 to increase the pressure, or the air (atmospheric pressure) is directly obtained by the air compressor 12, and the gas is compressed by the first booster pump 11 to increase the pressure to obtain high-pressure gas, and then the high-pressure gas is input into the constant pressure gas tank 9. The gas cylinder 10 and the air compressor can reach different extreme pressures, and the types of injected gases are different, and they can be selected according to actual needs.

[0065] Embodiment three:

[0066] The circulating liquid injection system includes: a first circulating pump 13, and a first anti-settling tank 14, a second anti-settling tank 15, and a third anti-settling tank 16 respectively connected thereto. Valves are respectively provided on the pipelines connecting the first circulating pump 13 and the first anti-settling tank 14, the second anti-settling tank 15, and the third anti-settling tank 16.

[0067] The first anti-settling tank 14, the second anti-settling tank 15, and the third anti-settling tank 16 are connected to the back pressure valve 20 through pipelines. An infrared liquid level monitor 17 and a valve are provided on the pipelines connecting the first anti-settling tank 14, the second anti-settling tank 15, and the third anti-settling tank 16 with the back pressure valve 20. The infrared liquid level monitor 17 is connected to the measurement and recording system. Preferably, a liquid-gas separator is also provided on the pipeline connecting the first anti-settling tank 14 with the back pressure valve 20. In the initial state, the first anti-settling tank 14 is empty, the second anti-settling tank 15 is filled with well killing fluid, and the third anti-settling tank 16 is filled with drilling fluid.

[0068] At the same time, the first circulation pump 13 is connected to the second booster pump 18, and the second booster pump 18 is connected to the drilling fluid interface on the drill string valve at the upper end of the drill string 3 through a pipeline, and a valve is arranged on the pipeline. The back pressure valve 20 is connected to the second interface on the gate blowout preventer 4.

[0069] Furthermore, the back pressure valve 20 is connected to the back pressure tracking pump 19 through a pipeline, and a pressure sensor and a valve are arranged on the pipeline.

[0070] The liquid is sucked by the first circulation pump 13 and sent to the kettle body after being pressurized, so as to realize the simulation of circulating liquid injection.

[0071] Embodiment 4:

[0072] The cement injection system includes an empty tank 21, a clean water tank 22, a cement ash tank 23 and a mixing tank 24. The empty tank 21, the clean water tank 22 and the cement ash tank 23 are connected to the mixing tank 24 through pipelines, and valves are provided on each pipeline. The mixing tank 24 is connected to the second circulation pump through a pipeline, and a valve is provided on the pipeline. The second circulation pump is connected to the back pressure valve 20 through a pipeline, and a check valve and a valve are provided on the pipeline. In the initial state, the empty tank 21 is empty, the clean water tank 22 is filled with clean water, and the cement ash tank 23 is filled with cement ash.

[0073] The second circulation pump sucks the liquid into the kettle body to simulate cement injection.

[0074] Embodiment five:

[0075] The measurement and recording system includes a computer 25 for recording data from the pressure detector 7, various pressure sensors, and an infrared liquid level monitor.

[0076] The following is an example of simulating the working conditions of a constant volume type fracture at a certain fracture scale (the scale is reflected in the distance between two fracture simulation plates) and angle (different angles with the horizontal plane):

[0077] Embodiment six:

[0078] (1) Formation fracture simulation: Start the mixing tank 24, open the valves between the clean water tank 22, the cement ash tank 23 and the mixing tank 24, and allow the cement ash and clean water to enter the mixing tank 24 in a certain ratio (the ratio can be controlled by releasing different amounts of materials by opening the two valves at different times). After being stirred in the mixing tank 24, the clean water and cement ash are mixed to form cement slurry. The cement slurry is pumped into the high-pressure reactor 1 by the second circulation pump through the back pressure valve 20 and the gate blowout preventer 4. After reaching a certain height (located below the pressure conduction hole 8), the injection is stopped, and the first fracture simulation plate 6 is placed. The fracture simulation plate 6 is supported by the cement slurry. After the cement solidifies, an annular pad is placed on the first fracture simulation plate 6, and a second fracture simulation plate 6 is placed on the annular pad. After continuing to inject cement, the second fracture simulation plate 6 is supported by the annular pad. A simulated fracture is formed between the two fracture simulation plates. Different heights and angles of the simulated fractures are achieved by different annular pads, that is, the height of the annular pad determines the height of the simulated fracture, and the angle between the annular pad and the horizontal plane determines the angle of the simulated fracture. The pressure conduction hole 8 is located between the two fracture simulation plates and can inject gas into the simulated fracture.

[0079] (2) Formation pressure simulation: Open the gas cylinder 10, pressurize the gas to a certain pressure through the air compressor 12 and the first booster pump 11, and then enter the constant pressure gas tank 9. Open the valve connecting the constant pressure gas tank 9 and the pressure conduction hole 8 to allow the high-pressure gas to enter the simulated fracture.

[0080] (3) Actual drilling overflow simulation: Turn on the first circulation pump 13, and inject the drilling fluid in the third anti-settling tank 16 into the drill string 3 through the second booster pump 18; at the same time, turn on the motor 2 to drive the drill string 3 and the PDC drill bit 5 to rotate and start drilling. The circulating drilling fluid and cement chips are returned to the third anti-settling tank 16 through the second interface of the gate blowout preventer 4. Open the back pressure valve 20 in advance, and keep the pressure data stable through the back pressure tracking pump 19. As the PDC drill bit 5 drills, the simulated fracture overflows, and the gate blowout preventer 4 is closed to simulate shut-in.

[0081] (4) Overflow well killing simulation: overflow well killing simulation can be performed using one of the following two methods:

[0082] Method 1 is horizontal push well pressure, which is specifically as follows: connect the outlet of the second booster pump 18 to the second interface of the gate blowout preventer 4, turn on the first circulation pump 13, and inject the well pressure fluid in the second anti-settling tank 15 into the annulus between the drill string 3 and the cement through the second interface of the gate blowout preventer 4 to simulate the horizontal push well pressure process.

[0083] Method 2 is throttling circulation well killing, which is specifically as follows: open the circulation pump 13, inject the well killing fluid in the second anti-settling tank 15 into the drill string through the drilling fluid interface of the drill string valve, and the liquid returned from the second interface of the gate blowout preventer 4 enters the liquid-gas separator through the back pressure valve 20, and the liquid after the high-pressure gas is discharged from the liquid-gas separator enters the first anti-settling tank 14, simulating the throttling circulation well killing process.

[0084] During the simulation process, the pressure detector 7, the infrared liquid level monitor 17 and the computer 25 are used to measure and record the parameters of the entire process, that is, the pressure magnitude and liquid level at each location are recorded.

[0085] In actual use, the device of the present invention can be used to simulate various types of overflow well killing in fracture-cavity gas reservoirs, as follows:

[0086] 1. Simulate cracks of different scales and angles. When there is no pressure supplement at the far end, the overflow well-killing process during flat-push well-killing is adopted. The details are as follows: inject a certain amount of cement (not more than one-third of the kettle height) through the cement injection system, place the first crack simulation plate before solidification, and place the second crack simulation plate after solidification. The two crack simulation plates are supported by an annular pad. The distance between the two crack simulation plates and the angle between the crack simulation plates and the horizontal plane can be adjusted by different annular pads, so as to simulate cracks of different scales and angles. Continue to inject the upper cement to fill the kettle. After the cement is completely solidified, inject a certain pressure of gas into the simulated crack through the high-pressure gas injection system, and then close the valve between the pressure conduction hole 8 and the constant pressure gas tank 9 to simulate no pressure supplement (that is, first inject a certain amount of gas through the pressure conduction hole 8, and then no longer inject gas). Open the circulating liquid injection system, start the real drilling overflow simulation, drill to the fracture simulation plate to simulate the overflow, and perform well killing through the overflow well-killing simulation method 1. Record the parameter changes (pressure size, liquid level) of cracks of different scales and angles through the measurement system.

[0087] 2. Simulate cracks of different scales and angles. When there is no pressure supplement at the far end, the overflow well-killing process during throttling circulation well-killing is adopted. The details are as follows: inject a certain amount of cement (not more than one-third of the kettle height) through the cement injection system, place the first crack simulation plate before solidification, and place the second crack simulation plate after solidification. The two crack simulation plates are supported by an annular pad. The distance between the two crack simulation plates or the angle with the horizontal plane is adjusted by the annular pad to simulate cracks of different scales and angles. Continue to inject upper cement to fill the kettle. After the cement is completely solidified, inject a certain pressure gas into the crack through the high-pressure gas injection system, and then close the valve between the pressure conduction hole 8 and the constant pressure gas tank 9 to simulate no pressure supplement (that is, first inject a certain amount of gas through the pressure conduction hole 8, and then no longer inject gas). Turn on the circulating liquid injection system, start the real drilling overflow simulation, drill to the crack simulation plate to simulate the overflow, and perform well killing through the overflow well-killing simulation method 2. Record the parameter changes (pressure size, liquid level) of cracks of different scales and angles through the measurement system.

[0088] 3. To simulate cracks of different scales and angles, when there is continuous pressure supplement at the far end, the overflow well-killing process during flat-push well-killing is adopted, as follows: a certain amount of cement is injected through the cement injection system (not exceeding one-third of the kettle height), the first crack simulation plate is placed before solidification, and the second crack simulation plate is placed after solidification. The two crack simulation plates are supported by an annular pad. The distance between the two crack simulation plates or the angle with the horizontal plane is adjusted by the annular pad to simulate cracks of different scales and angles. Continue to inject the upper cement to fill the kettle. After the cement is completely solidified, a certain pressure gas is injected into the crack through the high-pressure gas injection system, and the valve between the pressure conduction hole 8 and the constant pressure gas tank 9 is temporarily closed. Open the circulating liquid injection system, start the overflow simulation of real drilling, drill to the front of the crack simulation plate, open the valve between the pressure conduction hole 8 and the constant pressure gas tank 9, simulate the overflow, and perform well killing through the overflow well-killing simulation method 1, and record the parameter changes (pressure size, liquid level) of cracks of different scales and angles through the measurement system.

[0089] 4. To simulate cracks of different scales and angles, when there is continuous pressure supplement at the far end, the overflow well-killing process during throttling circulation well-killing is adopted, as follows: a certain amount of cement is injected through the cement injection system (not exceeding one-third of the kettle height), the first crack simulation plate is placed before solidification, and the second crack simulation plate is placed after solidification. The two crack simulation plates are supported by an annular pad. The distance between the two crack simulation plates or the angle with the horizontal plane is adjusted through the annular pad to simulate cracks of different scales and angles. Continue to inject the upper cement to fill the kettle, wait for the cement to completely solidify, inject a certain pressure gas into the crack through the high-pressure gas injection system, and temporarily close the valve between the pressure conduction hole 8 and the constant pressure gas tank 9. Open the circulating liquid injection system, start the overflow simulation of real drilling, drill to the front of the crack simulation plate, open the valve between the pressure conduction hole 8 and the constant pressure gas tank 9, simulate the overflow, and perform well killing through the overflow well-killing simulation method 2, and open the measurement system to record the parameter changes (pressure size, liquid level) of cracks of different scales and angles.

[0090] The present invention solves the problems that "general overflow simulation devices cannot continuously simulate the overflow well-killing process, the data collected is single, and the effects of drill string rotation, cracks, sizes, shapes and angles, and whether there is supplementation of formation pressure at the far end on overflow well-killing are not considered." The present invention can truly simulate the parameter change process of overflow well-killing in fracture-cavity gas reservoirs, and has the characteristics of continuous and real simulation, multi-condition coupling, multi-parameter measurable, and process visualization. Through the mutual cooperation of five major systems, including the fracture-cavity formation drilling simulation system, high-pressure gas injection system, circulating liquid injection system, cement injection system, and measurement and recording system, and using a high-pressure visual reactor as a simulation experiment site, various types of overflow well-killing processes such as different fracture scales, angles, constant volume type, and continuous high pressure type in fracture-cavity gas reservoirs are simulated, and the changes in multiple parameters in the process are measured and collected with high precision.

[0091] The present invention can simulate the continuous process of different types of overflows and different well-killing methods in fracture-cavity gas reservoirs, and continuously collect various data in the overflow and well-killing process, which can more realistically reflect the different overflow types and parameter characteristics of carbonate fracture-cavity oil and gas reservoirs, and provide data guidance for the overflow type judgment and well-killing method selection of on-site fracture-cavity gas reservoirs.

[0092] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connection" 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 a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0093] In the description of the present invention, unless otherwise specified, the terms "upper", "lower", "left", "right", "inside", "outside", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they cannot be understood as limitations on the present invention.

[0094] The above technical solution is only one implementation mode of the present invention. For those skilled in the art, it is easy to make various types of improvements or modifications based on the principles disclosed in the present invention, and it is not limited to the technical solution described in the above specific embodiments of the present invention. Therefore, the above description is only preferred and does not have a restrictive meaning.

Claims

1. A device for evaluating overflow and well killing rules of fracture-cavity gas reservoirs, characterized in that: The device comprises: a fracture-cavity formation drilling simulation system, and the following components respectively connected thereto: High-pressure gas injection system, used to inject gas into the fracture-cavity formation drilling simulation system; A circulating liquid injection system is used to inject circulating liquid into the fracture-cavity formation drilling simulation system; Cement injection system, used to inject cement into the fracture-cavity formation drilling simulation system; Measurement recording system, used to record data.

2. The device for evaluating overflow and well killing rules of fracture-cavity gas reservoirs according to claim 1, characterized in that: The fracture-cavity formation drilling simulation system comprises: a high-pressure reactor, a motor, a drill string, a gate blowout preventer, a PDC drill bit, and a fracture simulation board; The high-pressure reactor comprises: a reactor body and a support frame; the support frame is arranged above the reactor body, and the motor is arranged at the bottom of the support frame; The gate blowout preventer is arranged at the upper end of the kettle body; The motor is connected to the upper end of the drill string, and the lower end of the drill string passes through the gate blowout preventer and is connected to the PDC drill bit located in the inner cavity of the kettle; The crack simulation plate can be installed in the inner cavity of the kettle body; A pressure conduction hole is opened on the lower wall of the kettle body, and the pressure conduction hole is connected to the high-pressure gas injection system.

3. The device for evaluating overflow and well killing rules of fracture-cavity gas reservoirs according to claim 2, characterized in that: A drill string valve is provided at the upper end of the drill string, and a pressure gauge interface and a drilling fluid interface are provided on the drill string valve; The first interface of the ram blowout preventer is connected to a pressure sensor; The second interface of the ram blowout preventer is connected to a cement injection system and a circulating liquid injection system.

4. The device for evaluating overflow and well killing rules of fracture-cavity gas reservoirs according to claim 3 is characterized in that: The high-pressure gas injection system comprises: a constant-pressure gas tank, a gas cylinder, and a first booster pump; The gas cylinder is connected to the first booster pump through a pipeline, the first booster pump is connected to the constant pressure gas tank through a pipeline, and the constant pressure gas tank is connected to the pressure conduction hole through a pipeline; A valve is provided on the pipeline connecting the gas cylinder and the first booster pump; A valve, a check valve, a valve, and a pressure sensor are sequentially arranged on the pipeline connecting the first booster pump and the constant pressure gas tank; A valve is arranged on the pipeline connecting the constant pressure gas tank and the pressure conduction hole.

5. The device for evaluating overflow and well killing rules of fracture-cavity gas reservoirs according to claim 4, characterized in that: The high-pressure gas injection system further includes: an air compressor; the air compressor is connected to the first booster pump through a pipeline, and a one-way valve, a pressure gauge, and a valve are arranged in sequence on the pipeline.

6. The device for evaluating overflow and well killing rules of fracture-cavity gas reservoirs according to claim 1, characterized in that: The circulating liquid injection system comprises: a first circulating pump, and a first anti-settling tank, a second anti-settling tank, and a third anti-settling tank respectively connected thereto; valves are respectively arranged on the pipelines connecting the first circulating pump and the first anti-settling tank, the second anti-settling tank, and the third anti-settling tank; The first anti-settling tank, the second anti-settling tank and the third anti-settling tank are respectively connected to the back pressure valve through pipelines, and infrared liquid level monitors and valves are respectively arranged on the pipelines.

7. The device for evaluating overflow and well killing rules of fracture-cavity gas reservoirs according to claim 6, characterized in that: A liquid-gas separator is also provided on the pipeline connecting the first anti-settling tank and the back pressure valve.

8. The device for evaluating overflow and well killing rules of fracture-cavity gas reservoirs according to claim 6, characterized in that: The first circulation pump is connected to the second booster pump, and the second booster pump is connected to the drilling fluid interface on the drill string valve through a pipeline, and a valve is provided on the pipeline; The back pressure valve is connected to the second interface on the gate blowout preventer.

9. The device for evaluating overflow and well killing rules of fracture-cavity gas reservoirs according to claim 8, characterized in that: The back pressure valve is connected to the back pressure tracking pump through a pipeline, and a pressure sensor and a valve are arranged on the pipeline.

10. The device for evaluating overflow and well killing rules of fracture-cavity gas reservoirs according to claim 1, characterized in that: The cement injection system includes an empty tank, a clean water tank, a cement ash tank and a mixing tank; The empty tank, clean water tank and cement ash tank are connected to the mixing tank through pipelines, and valves are respectively provided on the pipelines; The stirring tank is connected to the second circulation pump through a pipeline, and a valve is arranged on the pipeline; The second circulation pump is connected to the back pressure valve through a pipeline, and a one-way valve and a valve are arranged on the pipeline.

11. A method for using the device for evaluating overflow and well killing rules of fracture-cavity gas reservoirs according to any one of claims 1 to 10, characterized in that: The method comprises: The device is used to simulate the following overflow well killing process: For fractures of different scales and angles, when there is no pressure supplement at the far end, the overflow well-killing process is adopted when flat-push well-killing is used; For fractures of different scales and angles, when there is no pressure supplement at the far end, the overflow well killing process when throttling circulation well killing is adopted; For fractures of different scales and angles, when there is continuous pressure supplement at the far end, the overflow well-killing process of flat-push well-killing is adopted; For fractures of different scales and angles, when there is continuous pressure replenishment at the far end, the overflow well-killing process during throttling circulation well-killing is adopted.

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