An experimental apparatus, system, and method for simulating tubing leaks in gas injection wells

Abstract

The present application belongs to the technical field of downhole tubing leak detection of gas injection wells, and discloses an experimental device, system and method for simulating tubing leak of a gas injection well. The experimental device comprises a tubing leak simulation wellbore device, which comprises a transparent casing and a tubing arranged in the transparent casing. A plurality of mounting holes are formed in the tubing, for mounting a given number of leak hole simulation devices, and a non-hole bolt plug is mounted on the remaining mounting holes for sealing. The leak hole simulation device is a bolt plug with holes, comprising a bolt with holes, a first gasket, a bursting disc and a plug with holes. A leak bolt hole is formed in the bolt with holes, and a first gasket and a bursting disc are mounted in the leak bolt hole to achieve hole sealing. The outer end of the leak bolt hole is tightly connected with the plug with holes, and a leak hole is formed in the plug with holes. The present application can simulate the flow field change in the annulus between the oil casing and the tubing and the wellhead pressure change at the moment of tubing rupture and leak of a gas injection well.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of downhole tubing leakage detection of gas injection wells, especially to the technical field of gas flooding tertiary oil recovery, and specifically relates to an experimental device, system and method for simulating tubing leakage of gas injection wells. BACKGROUND

[0002] In recent years, with the continuous aggravation of the trend of poor quality of newly proven reserves, the calibrated recovery rate of the one-time development using horizontal wells + volume fracturing and the secondary oil recovery using conventional water injection is generally lower than 15%, while the gas flooding tertiary oil recovery is an important direction to improve the recovery rate of low-permeability and tight oil reservoirs. The types of injected gas mainly include carbon dioxide, hydrocarbon gas, nitrogen, flue gas, and reduced-oxygen air. A gas injection well is a well in which gas is continuously injected into a formation to displace crude oil in the formation. Due to the characteristics of high pressure and corrosion of the injected fluid, leakage is prone to occur at the tubing hanger, tubing thread, and packer of the gas injection well. Once the gas injection well leaks, it is easy to cause problems such as continuous pressure in the annulus and corrosion of the oil casing, which endangers the safety of production and has a negative impact on the long-term service performance of the pipe string. However, the current understanding of the gas flow field change and the change rule of casing pressure under different leakage positions and leakage hole sizes of the gas injection well is unclear.

[0003] Chinese patent CN213478283U discloses a downhole tubing leakage simulation system, which includes a pipe string simulation unit, a fluid simulation unit, and a fluid collection unit. The pipe string simulation unit of the utility model includes a horizontal section, a curved section, and a vertical section connected in sequence, the lower end of the vertical section forms an inlet end, and the end of the horizontal section opposite to the vertical section forms an outlet end; the horizontal section forms a pipe body and an annulus simulation part, the curved section forms a liquid level simulation part, and the outlet end is provided with a wellhead simulation part; the patent can simulate the downhole tubing leakage. However, since the gas injection wells in oilfields are generally straight wells, the annulus liquid level in the straight well is a horizontal plane or an approximately horizontal plane, and the patent only uses a curved pipe section to simulate the horizontal annulus liquid level, which has a large gap with the actual working condition, and cannot simulate the flow field in the tubing-casing annulus and the change of wellhead pressure after the tubing ruptures instantaneously during the tubing gas injection process.

[0004] Chinese patent CN110469325A discloses a method for finding a leakage point of a gas injection pipe string in an oil and gas field. The method uses a downhole television and a casing annulus pressure test to find the leakage point of the gas injection pipe string in real time and intuitively and accurately. However, the method for finding the leakage point of the gas injection pipe string in the oil and gas field is a method for judging the leakage position of a suspected leakage injection well in an actual construction process by using a downhole testing tool, which does not belong to an indoor simulation method for tubing leakage of a gas injection well, and cannot simulate the flow field in the tubing-casing annulus and the change of wellhead pressure after the tubing ruptures instantaneously during the tubing gas injection process, and realize the visual observation of the change of the leakage flow field.

[0005] In summary, no indoor simulation experiment device, experiment system and corresponding experiment method for accurately simulating tubing leakage of gas injection wells have been found to study the fluid flow characteristics of tubing leakage of gas injection wells and the change of wellhead casing pressure. SUMMARY

[0006] The present application aims to solve the technical problems in the prior art, and provides an experiment device, system and method for simulating tubing leakage of gas injection wells, which can be used to simulate the flow field change in the tubing leakage annulus and the wellhead pressure change at the moment of tubing rupture leakage of gas injection wells under different casing pressure differentials, and the leakage hole experiment parameters and burst pressure are simple to adjust and the leakage flow field change can be observed.

[0007] To achieve the above technical purposes, the present application adopts the following technical solutions:

[0008] An experiment device for simulating tubing leakage of gas injection wells, comprising: a tubing leakage simulation wellbore device and a leakage hole simulation device;

[0009] The tubing leakage simulation wellbore device comprises a transparent casing and a tubing arranged in the transparent casing; the tubing is provided with a plurality of mounting holes for mounting a predetermined number of leakage hole simulation devices, and the remaining mounting holes are provided with non-hole bolt plugs for sealing;

[0010] The leakage hole simulation device is a hole bolt plug, comprising a hole bolt, a first gasket, a bursting disc and a hole plug; the hole bolt is provided with a leakage bolt hole, the first gasket and the bursting disc are arranged in the leakage bolt hole to realize hole sealing, the hole plug is tightly connected to the outer end of the leakage bolt hole, and the hole plug is provided with a leakage hole.

[0011] Further, a plurality of leakage hole replacement devices are mounted on the outer pipe wall of the transparent casing, and the leakage hole replacement devices are arranged corresponding to the mounting holes on the tubing.

[0012] Further, the leakage hole replacement device comprises a boss arranged on the outer pipe wall of the transparent casing; the boss is a hollow cylindrical structure, and the boss end side is connected to a cover plate through a flange plate for sealing.

[0013] Further, the transparent casing of the tubing leakage simulation wellbore device comprises a plurality of casing joints, each casing joint is provided with a flange plate at both ends, and the plurality of casing joints are connected end to end through the flange plates to form the transparent casing.

[0014] Further, it further comprises a rotatable driving base device, which comprises a hinged base, a hinged disc and a driving motor.

[0015] The transparent casing of the tubing leakage simulation wellbore device is connected to the hinged disc at the bottom end.

[0016] The articulated disc is articulated on the articulated base, and the driving motor is arranged on one side of the articulated base and drives the articulated disc;

[0017] The driving motor drives the rotation of the articulated disc, so that the leak simulation wellbore device connected on the articulated disc can be laid down or erected to simulate a horizontal wellbore or a vertical wellbore.

[0018] Further, the articulated disc comprises a connecting disc and an articulated leg arranged below the connecting disc; the articulated base comprises a bottom plate and an articulated support arranged on the bottom plate; the articulated leg and the articulated support are articulated through two left and right articulated bolts;

[0019] The articulated support is provided with a driving motor on one side, and the driving motor drives the articulated disc through a driving shaft and a second gasket.

[0020] Meanwhile, the present application provides an experimental system for simulating gas injection well tubing leakage, which comprises the experimental device according to any one of the above, and further comprises a gas injection circulating system, a nitrogen purging module, a gas absorption module and an annular protective liquid level control module;

[0021] The gas injection circulating system is a closed circulating pipeline composed of an injection pipeline, the experimental device for simulating gas injection well tubing leakage and a return pipeline;

[0022] The injection pipeline is externally connected with an experimental gas cylinder and a nitrogen cylinder, and the nitrogen cylinder constitutes the nitrogen purging module;

[0023] The injection pipeline is sequentially provided with a first valve, a liquid storage tank, a flow meter, a delivery pump, a high-pressure valve, a temperature adjusting device and an inlet valve; and the return pipeline is sequentially provided with an outlet valve, a filter and a second valve;

[0024] A third valve and a gas absorption treatment container are connected in parallel on the pipeline between the second valve and the injection pipeline, and the third valve and the gas absorption treatment container constitute the gas absorption module;

[0025] The experimental device for simulating gas injection well tubing leakage is further connected in parallel with a centrifugal pump, the centrifugal pump is connected to the annular protective liquid device, a fourth valve is arranged on the pipeline between the centrifugal pump and the annular protective liquid device, and the centrifugal pump, the fourth valve and the annular protective liquid device constitute the annular protective liquid level control module.

[0026] Further, a gas dyeing agent is added in the experimental gas cylinder for dyeing the gas in the experimental gas cylinder.

[0027] Further, the nitrogen cylinder and the experimental cylinder are connected in parallel to a collective gas injection pipeline, and the collective gas injection pipeline is connected to the injection pipeline.

[0028] Further, the experimental device for simulating the leakage of the gas injection well tubing is provided with a pressure sensor at the upper end of the tubing leakage simulation wellbore device for monitoring the wellhead pressure change of the tubing leakage simulation wellbore device.

[0029] Further, a high-speed camera is further included for shooting the flow field change in the tubing-casing annulus during the tubing gas injection process.

[0030] In addition, the application further provides an experimental method for simulating the leakage of the gas injection well tubing, which is implemented by using the experimental system according to any one of the above.

[0031] Step S1: air-tightness test is performed on the system circulation pipeline by using nitrogen, and air is discharged;

[0032] Step S2: the inlet valve is closed, the experimental cylinder and the delivery pump are opened, gas is injected into the liquid storage tank, and the temperature adjusting device is used to adjust the gas temperature to generate gas with the set temperature and pressure;

[0033] Step S3: the inlet valve is opened, the outlet valve is closed, the gas with the adjusted temperature and pressure is injected into the tubing leakage simulation wellbore device of the experimental device for simulating the leakage of the gas injection well tubing, when the gas pressure in the tubing of the tubing leakage simulation wellbore device reaches the rupture pressure of the rupture disc, the gas leaks through the leakage hole of the leakage hole simulation device to the annulus;

[0034] Step S4: the high-speed camera is used to shoot the flow field change in the tubing-casing annulus at the moment of gas leakage; at the same time, the pressure sensor arranged at the upper end of the tubing leakage simulation wellbore device is used to monitor and collect the wellhead pressure change data from the initial injection to the tubing-casing differential pressure stabilization of the gas;

[0035] Step S5: the experimental cylinder, the first valve, the delivery pump and the inlet valve are closed, the outlet valve, the second valve and the third valve are opened, and the gas in the gas circulation system is filtered through the filter and then discharged into the gas absorption treatment container;

[0036] Step S6: after the pressure discharge is completed, the installation number, the installation position, the leakage hole diameter size and the rupture disc pressure grade type used in the leakage hole simulation device are adjusted, and steps S1-S5 are repeated to complete the leakage simulation experiment under different experimental conditions;

[0037] Step S7: After the experiment, close the experimental gas cylinder, open the nitrogen gas cylinder, gas injection circulation system and gas absorption treatment container, use nitrogen to purge the residual gas in the pipeline of the experimental system, and use the gas absorption treatment container to treat the residual gas; after all the residual gas in the system is discharged, close the nitrogen gas cylinder and the gas absorption treatment container, and seal the experimental system.

[0038] Compared with the prior art, the beneficial effects of the present application are:

[0039] (1) The experimental device for simulating the leakage of the oil pipe of the gas injection well provided by the present application can simulate the flow field change and wellhead pressure change in the casing annulus after the instantaneous rupture and leakage of the oil pipe during the oil pipe gas injection process, and can realize the visual observation of the simulation device and the visualization of the leakage flow field through the transparent casing pipe, which has the advantages of simple adjustment of the instantaneous working condition of the oil pipe rupture and leakage, leakage hole experimental parameters (adjusting the installation position, number and leakage hole diameter of the leakage hole simulation device) and burst pressure (replacing the bursting disc), and can observe the leakage flow field change.

[0040] (2) The experimental device for simulating the leakage of the oil pipe of the gas injection well provided by the present application can simulate different lengths of wellbore devices by connecting a plurality of casing spools end to end; the transparent casing pipe is made of transparent organic glass, which facilitates the observation of the flow field change in the casing annulus of the simulated wellbore device; the leakage hole replacement device is arranged on the outer wall of the transparent casing pipe, which facilitates the adjustment of the installation position and number of the leakage hole simulation device, and the replacement of the leakage hole simulation device with different pressure grade bursting discs and / or different size leakage holes.

[0041] (3) The experimental device for simulating the leakage of the oil pipe of the gas injection well provided by the present application can control the laying and standing of the oil pipe leakage simulation wellbore device connected to the hinged disc by driving the hinged disc through the rotatable drive base device driven by the driving motor, which facilitates the simulation of horizontal wellbore or vertical wellbore, saves manpower and improves efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0042] Figure 1 It is the overall structure schematic diagram of the experimental device for simulating the leakage of the oil pipe of the gas injection well of the embodiment of the present application.

[0043] Figure 2 It is the structure schematic diagram of the oil pipe leakage simulation wellbore device of the embodiment of the present application.

[0044] Figure 3 exploded view of a tubing leak simulation wellbore device according to an embodiment of the present application;

[0045] Figure 4 schematic view of a rotatable drive base device according to an embodiment of the present application;

[0046] Figure 5 exploded view of a rotatable drive base device according to an embodiment of the present application;

[0047] Figure 6 schematic view of a burst disk equipped leak hole simulation device according to an embodiment of the present application;

[0048] Figure 7 exploded view of a burst disk equipped leak hole simulation device according to an embodiment of the present application;

[0049] Figure 8 schematic view of an experimental system for simulating tubing leaks in gas injection wells according to an embodiment of the present application. DETAILED DESCRIPTION

[0050] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0051] In the description of the present application, it should be understood that the terms "coaxial", "bottom", "one end", "top", "middle", "the other end", "upper", "one side", "top", "inner", "front", "central", "both ends" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present 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, and therefore cannot be understood as a limitation of the present application.

[0052] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "setting", "connecting", "fixing", "screwed", and the like should be understood broadly, for example, can be fixedly connected, or can be detachably connected, or can be integrated; can be mechanically connected, or can be electrically connected; can be directly connected, or can be indirectly connected through an intermediate medium; can be the internal communication of two elements or the interaction relationship between two elements, unless otherwise explicitly limited, and those skilled in the art can understand the specific meaning of the above terms in the present application according to the specific circumstances.

[0053] Embodiment 1

[0054] In combination Figures 1-7 As shown in the figure, the embodiment of the present application provides an experimental device for simulating the leakage of the oil pipe of the gas injection well, which comprises an oil pipe leakage simulation wellbore device 1, a rotatable driving base device 2 and a leakage hole simulation device 3.

[0055] The oil pipe leakage simulation wellbore device 1 comprises a transparent casing 101 and an oil pipe 102 arranged in the transparent casing 101; the bottom end of the transparent casing 101 is connected to the rotatable driving base device 2; a plurality of mounting holes 1021 are formed on the oil pipe 102, which are used to mount a certain number of leakage hole simulation devices 3, and non-hole bolt plugs are mounted on the remaining mounting holes 1021 to seal them.

[0056] The leakage hole simulation device 3 is a hole bolt plug, as shown in the figure, which comprises a hole bolt 301, a first gasket 302, a bursting disc 303 and a hole plug 304; a leakage bolt hole 3011 is formed on the hole bolt 301, and the first gasket 302 and the bursting disc 303 are mounted in the leakage bolt hole 3011 to achieve hole sealing, and the hole plug 304 is threadedly connected to the outer end of the leakage bolt hole 3011, and a leakage hole 3041 is formed on the hole plug 304. Figures 6-7 When the gas pressure in the oil pipe reaches the rupture pressure of the bursting disc, the gas leaks through the leakage hole of the leakage hole simulation device on the oil pipe into the annulus, thereby being able to simulate the flow field change in the oil sleeve annulus and the wellhead pressure change after the instantaneous rupture and leakage of the oil pipe during the oil pipe gas injection process; wherein the pressure rating of the bursting disc 303 and the aperture size of the leakage hole 3041 are both specifically set according to experimental requirements.

[0057] Specifically, as shown in the figure, the transparent casing 101 of the oil pipe leakage simulation wellbore device 1 comprises two casing spools 1011, and a flange plate is arranged at each end of each casing spool 1011, and the two casing spools 1011 are connected to form the transparent casing 101 through the middle flange plate; in other embodiments, the number of casing spools can also be adjusted as needed in order to simulate wellbore devices of different lengths.

[0058] Figures 2-3 The flange plate at the upper end of the transparent casing 101 is fixedly connected with an oil pipe hanger 103, the oil pipe hanger 103 is fixedly connected with an oil pipe hanger flange 104, and the bottom end of the oil pipe hanger flange 104 is fixedly connected with the oil pipe 102.

[0059] The flange plate at the upper end of the transparent casing 101 is fixedly connected with an oil pipe hanger 103, the oil pipe hanger 103 is fixedly connected with an oil pipe hanger flange 104, and the bottom end of the oil pipe hanger flange 104 is fixedly connected with the oil pipe 102.

[0060] ​In the embodiment of the present application, the transparent sleeve 101 is made of transparent organic glass, which facilitates the observation of the leakage flow field change of the experimental simulation device.

[0061] In the embodiment of the present application, three leakage hole replacement devices 1012 are installed on the outer pipe wall of each sleeve 1011, which correspond to the installation holes 1021 on the oil pipe 102, so as to adjust the number and position of the leakage hole simulation device 3 on the installation hole 1021; the installation hole 1021 is provided with seven, and the fourth installation hole 1021 in the middle is a spare hole.

[0062] Specifically, the leakage hole replacement device 1012 includes a boss provided on the outer pipe wall of the transparent sleeve 101, the boss is a hollow cylindrical structure, and the boss end side is connected with a cover plate through a flange plate for sealing.

[0063] As shown in Figures 4-5 , the rotatable driving base device 2 includes a hinged base 201, a hinged disc 202 and a driving motor 203.

[0064] The bottom end of the transparent sleeve 101 of the oil pipe leakage simulation wellbore device 1 is connected with the hinged disc 202 through a flange plate. The hinged disc 202 includes a connecting disc 2021 and a hinged leg 2022 provided below the connecting disc 2021; the hinged base 201 includes a bottom plate 2011 and a hinged support 2012 provided on the bottom plate 2011; the hinged leg 2022 and the hinged support 2012 are hinged through two left and right hinged bolts 204; one side of the hinged support is provided with a driving motor 203, and the driving motor 203 is drivingly connected with the hinged disc 202 through a driving shaft 205 and a second gasket 206.

[0065] The hinged disc 202 is driven to rotate by the driving motor 203, so as to control the oil pipe leakage simulation wellbore device 1 connected on the hinged disc 202 to be laid down or upright, thereby facilitating the simulation of horizontal wellbore or vertical wellbore.

[0066] Embodiment 2

[0067] The embodiment of the present application provides an experimental system for simulating the oil pipe leakage of a gas injection well, which comprises the experimental device 6 for simulating the oil pipe leakage of a gas injection well as described in embodiment 1, and further comprises a gas injection circulation system, a nitrogen purging module, a gas absorption module and an annular protection liquid level control module.

[0068] Specifically, as shown in Figure 8 , the gas injection circulation system is a closed circulation pipeline composed of an injection pipeline 5, the experimental device 6 for simulating the oil pipe leakage of a gas injection well and a return pipeline 7.

[0069] The injection pipeline 5 is connected with an experimental gas cylinder 4 and a nitrogen cylinder 8, and the nitrogen cylinder 8 forms a nitrogen purging module.

[0070] The first valve 26, the liquid storage tank 11, the flow meter 12, the delivery pump 13, the high-pressure valve 14, the temperature adjusting device 15 and the inlet valve 16 are sequentially arranged on the injection pipeline 5, and the outlet valve 27, the filter 19 and the second valve 25 are sequentially arranged on the return pipeline 7.

[0071] The third valve 24 and the gas absorption treatment container 9 are connected in parallel on the pipeline between the second valve 25 and the injection pipeline 5, and the third valve 24 and the gas absorption treatment container 9 form a gas absorption module.

[0072] The experimental device 6 for simulating the leakage of the oil pipe of the gas injection well is also connected in parallel with the centrifugal pump 17, the centrifugal pump 17 is connected to the annular protective liquid device 18, the fourth valve 10 is arranged on the pipeline between the centrifugal pump 17 and the annular protective liquid device 18, and the centrifugal pump 17, the fourth valve 10 and the annular protective liquid device 18 form an annular protective liquid level control module. Specifically, a certain height of annular protective liquid is pumped into the experimental device 6 for simulating the leakage of the oil pipe of the gas injection well by the centrifugal pump 17 before the experiment, and the liquid level is kept constant before the rupture of the bursting disc during the experiment.

[0073] In the embodiment of the present application, the experimental gas cylinder 4 is used to provide a gas source for experiment simulation, and the experimental gas cylinder 4 is parallelly connected with two cylinders, one of which is used and the other of which is reserved. At the same time, in order to facilitate the observation of the change of the gas flow field, a gas dye is injected into the experimental gas cylinder 4 before the experiment, and the gas absorbs the gas dye to carry color.

[0074] The nitrogen cylinder 8 is connected in parallel with the experimental gas cylinder 4 to a collective gas injection pipeline, the nitrogen cylinder 8 is used to test the air tightness of the system pipeline and empty the air before the experiment, and the nitrogen cylinder 8 is used to purge the residual gas in the experimental system pipeline after the experiment; and the collective gas injection pipeline is connected with the injection pipeline 5.

[0075] In addition, the fifth valve 20 is arranged on the gas injection pipeline of the nitrogen cylinder 8, the sixth valve 21 and the seventh valve 22 are respectively arranged on the gas injection pipelines of the two experimental gas cylinders 4, and the eighth valve 23 is arranged on the collective gas injection pipeline.

[0076] The liquid storage tank 11 on the injection pipeline 5 is used to buffer gas, and the flow meter 12 is used to measure the injection gas flow; and the delivery pump 13 is used to deliver gas to the temperature adjusting device 15 to adjust the temperature, so as to generate gas with a set temperature and pressure.

[0077] The filter 19 on the return pipeline 7 is used to filter the impurities in the circulating gas, and in order to improve the filtering effect, the filter 19 is two in series.

[0078] The experimental device 6 for simulating the oil pipe leakage of the gas injection well is provided with a pressure sensor on the upper end flange cover of the oil pipe leakage simulation wellbore device 1, for monitoring the wellhead pressure change of the oil pipe leakage simulation wellbore device 1.

[0079] In addition, the experimental system further comprises a high-speed camera, which is used to shoot the flow field change in the oil-casing annulus during the oil pipe gas injection process.

[0080] Embodiment 3

[0081] The embodiment of the present application provides an experimental method for simulating the oil pipe leakage of the gas injection well, which is implemented by using the experimental system for simulating the oil pipe leakage of the gas injection well as described in embodiment 2.

[0082] In the embodiment of the present application, the following initial experimental conditions are set:

[0083] The number of the leakage hole simulation device 3 is 1, which is installed on the installation hole 1021 at the lowermost end of the oil pipe 102 of the oil pipe leakage simulation wellbore device 1; the aperture size of the leakage hole 3041 of the leakage hole simulation device 3 is 3mm, and the pressure grade of the bursting disc 303 is 2MPa; and the annulus protection liquid height is half of the height of the oil pipe leakage simulation wellbore device 1.

[0084] In the embodiment of the present application, the experimental method comprises the following steps:

[0085] Step S1: The system circulation pipeline is tested for air tightness by using nitrogen and the air is emptied;

[0086] Step S2: The inlet valve 16 is closed, the experimental gas cylinder 4 and the delivery pump 13 are opened, the gas is injected into the liquid storage tank 11, and the temperature adjusting device 15 is used to adjust the gas temperature, so as to generate the gas with the set temperature and pressure;

[0087] Step S3: The inlet valve 16 is opened, the outlet valve 27 is closed, the gas with the adjusted temperature and pressure is injected into the oil pipe leakage simulation wellbore device 1 of the experimental device 6 for simulating the oil pipe leakage of the gas injection well, when the gas pressure in the oil pipe 102 of the oil pipe leakage simulation wellbore device 1 reaches the rupture pressure of the bursting disc 303, the gas is leaked to the annulus through the leakage hole 3041 on the leakage hole simulation device 3 on the oil pipe 102;

[0088] Step S4: the flow field change in the oil jacket annulus at the moment of gas leakage is shot by a high-speed camera; at the same time, the pressure sensor arranged at the upper end of the tubing leakage simulation wellbore device 1 is used to monitor and collect the wellhead pressure change data from the initial injection to the stable casing pressure difference of the gas;

[0089] Step S5: the experimental gas cylinder 4, the first valve 26, the delivery pump 13 and the inlet valve 16 are closed, the outlet valve 27, the second valve 25 and the third valve 24 are opened, and the gas pressure in the gas circulation system is filtered through the filter 19 and then discharged into the gas absorption treatment container 9;

[0090] Step S6: after the pressure is discharged, the installation number, installation position, leakage hole diameter size and used burst disc pressure grade type of the leakage hole simulation device 3 are adjusted by the leakage hole replacement device 1012, and steps S1-S5 are repeated to complete the leakage simulation experiment under different experimental conditions;

[0091] Step S7: after the experiment is completed, the experimental gas cylinder 4 is closed, the nitrogen gas cylinder 8, the gas injection circulation system and the gas absorption treatment container 9 are opened, the residual gas in the pipeline of the experimental system is purged by nitrogen, and the residual gas is treated by the gas absorption treatment container 9; after the residual gas in the system is completely discharged, the nitrogen gas cylinder 8 and the gas absorption treatment container 9 are closed, and the experimental system is sealed by nitrogen to avoid corrosion and damage of the pipeline equipment.

[0092] The above only describes the embodiments of the present application and does not limit the present application. Any modification, equivalent replacement and improvement within the scope of the application should be included in the protection scope of the present application.

Claims

1. An experimental apparatus for simulating tubing leaks in gas injection wells, characterized in that, The oil pipe leakage simulation wellbore device and the leakage hole simulation device are included. The oil pipe leakage simulation wellbore device includes a transparent sleeve and an oil pipe arranged in the transparent sleeve; a plurality of installation holes are formed in the oil pipe, and a predetermined number of leakage hole simulation devices are arranged in the installation holes; and a non-hole bolt plug is arranged in the remaining installation holes to seal the remaining installation holes. The leakage hole simulation device is a hole bolt plug, which includes a hole bolt, a first gasket, a bursting disc and a hole plug; a leakage bolt hole is formed in the hole bolt, and the leakage bolt hole is sealed by the first gasket and the bursting disc; the outer end of the leakage bolt hole is connected to the hole plug; and a leakage hole is formed in the hole plug. A plurality of leakage hole replacement devices are arranged on the outer wall of the transparent sleeve, and the leakage hole replacement devices correspond to the installation holes of the oil pipe. The leakage hole replacement device includes a boss arranged on the outer wall of the transparent sleeve; the boss is a hollow cylindrical structure, and the boss is connected to a cover plate through a flange to seal the boss. The transparent sleeve of the oil pipe leakage simulation wellbore device includes a plurality of sleeve joints; a flange is arranged at each end of each sleeve joint; and the sleeve joints are connected end to end through the flanges to form the transparent sleeve. A rotatable driving base device is further included, which includes a hinged base, a hinged disc and a driving motor. The bottom end of the transparent sleeve of the oil pipe leakage simulation wellbore device is connected to the hinged disc. The hinged disc is hinged to the hinged base, and the driving motor is arranged on one side of the hinged base and is connected to the hinged disc to drive the hinged disc. The hinged disc is driven to rotate by the driving motor, and the oil pipe leakage simulation wellbore device connected to the hinged disc can be laid down or stood up to simulate a horizontal wellbore or a vertical wellbore. The hinged disc includes a connecting disc and a hinged leg arranged below the connecting disc; the hinged base includes a bottom plate and a hinged support arranged on the bottom plate; and the hinged leg and the hinged support are hinged through two left and right hinged bolts.

2. The experimental setup of claim 1, wherein, A driving motor is arranged on one side of the hinged support, and the driving motor is connected to the hinged disc through a driving shaft and a second gasket. An air injection circulation system, a nitrogen purging module, a gas absorption module and an annular protective liquid level control module are further included.

3. An experimental system for simulating tubing leaks in gas injection wells, comprising an experimental device as claimed in any one of claims 1-2, characterized in that, The air injection circulation system is a closed circulation pipeline composed of an injection pipeline, an experimental device for simulating oil pipe leakage of an air injection well and a return pipeline. An experimental gas cylinder and a nitrogen cylinder are connected to the injection pipeline, and the nitrogen cylinder constitutes the nitrogen purging module. A first valve, a liquid storage tank, a flow meter, a delivery pump, a high-pressure valve, a temperature adjusting device and an inlet valve are sequentially arranged on the injection pipeline; an outlet valve, a filter and a second valve are sequentially arranged on the return pipeline. A third valve and a gas absorption treatment container are connected to the pipeline between the second valve and the injection pipeline, and the third valve and the gas absorption treatment container constitute the gas absorption module. ​ The experimental apparatus for simulating gas injection well tubing leakage is also connected to a centrifugal pump, which is connected to an annular protection fluid device. A fourth valve is installed on the pipeline between the centrifugal pump and the annular protection fluid device. The centrifugal pump, the fourth valve, and the annular protection fluid device constitute the annular protection fluid level control module.

4. The experimental system of claim 3, wherein, The experimental gas cylinder contains a gas dyeing agent for coloring the gas inside.

5. The experimental system of claim 4, wherein, The nitrogen cylinder and the experimental gas cylinder are connected in parallel to the main gas injection line, which is connected to the injection line.

6. The experimental system of claim 3, wherein, The experimental device for simulating tubing leakage in gas injection wells has a pressure sensor installed at the upper end of the tubing leakage simulation wellbore device to monitor changes in wellhead pressure.

7. The experimental system of claim 3, wherein, It also includes a high-speed camera to capture the flow field changes in the annulus during the gas injection process in the oil pipe.

8. An experimental method for simulating tubing leak in a gas injection well, carried out using the experimental system according to any one of claims 3-7, characterized in that, The method includes the following steps: Step S1: Use nitrogen to test the airtightness of the system circulation pipeline and purge the air; Step S2: Close the inlet valve, turn on the experimental gas cylinder and delivery pump, inject gas into the storage tank, and use the temperature regulating device to adjust the gas temperature to generate the gas at the temperature and pressure set in the experiment. Step S3: Open the inlet valve and close the outlet valve. Inject the gas with adjusted temperature and pressure into the tubing leakage simulation wellbore device of the experimental device for simulating tubing leakage in gas injection wells. When the gas pressure in the tubing of the tubing simulation wellbore device reaches the rupture pressure of the rupture disc, the gas leaks into the annulus through the leakage hole on the tubing and the leakage hole on the simulation device. Step S4: Use a high-speed camera to capture the flow field changes in the annulus during the gas leak; at the same time, use a pressure sensor installed at the top of the tubing leak simulation wellbore device to monitor and collect wellhead pressure change data from the initial gas injection to the point where the oil-casing pressure differential stabilizes. Step S5: Close the experimental gas cylinder, the first valve, the delivery pump, and the inlet valve; open the outlet valve, the second valve, and the third valve to release the gas pressure in the gas circulation system into the gas absorption and treatment container after filtration. Step S6: After the pressure is released, adjust the number of leakage hole simulation devices, their installation positions, leakage hole diameters, and the type of rupture disc pressure rating used. Repeat steps S1-S5 to complete leakage simulation experiments under different experimental conditions. Step S7: After the experiment, close the experimental gas cylinder, open the nitrogen cylinder, gas circulation system and gas absorption and treatment container, purge the residual gas in the experimental system pipeline with nitrogen, and treat the residual gas with the gas absorption and treatment container; after all the residual gas in the system is discharged, close the nitrogen cylinder and gas absorption and treatment container, and seal the experimental system.

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