Experimental device, system and method for simulating leakage of oil pipe of gas injection well

Abstract

The invention belongs to the technical field of gas-injection well downhole oil pipe leakage detection, and discloses an experimental device, system and method for simulating gas-injection well oil pipe leakage. The experimental device comprises an oil pipe leakage simulation wellbore device, wherein the oil pipe leakage simulation wellbore device comprises a transparent sleeve and an oil pipe arranged in the transparent sleeve; a plurality of mounting holes are formed in the oil pipe and used for mounting a set number of leakage hole simulation devices, and hole-free bolt plugs are mounted on the remaining mounting holes for sealing; the leakage hole simulation device is a holed bolt plug and comprises a holed bolt, a first gasket, a rupture disk and a holed plug; a leakage bolt hole is formed in the holed bolt, a first gasket and a rupture disk are installed in the leakage bolt hole to achieve hole sealing, the outer end of the leakage bolt hole is connected with a holed plug in a fastened mode, and a leakage hole is formed in the holed plug. The device can simulate the flow field change and wellhead pressure change in the oil sleeve annulus at the moment of fracture and leakage of the oil pipe of the gas injection well.

Description

Technical Field

[0001] The invention belongs to the technical field of downhole oil pipe leakage detection in gas injection wells, in particular to the technical field of gas drive tertiary oil recovery, and specifically to an experimental device, system and method for simulating oil pipe leakage in gas injection wells. Background Art

[0002] In recent years, as the trend of the quality of newly discovered reserves continues to intensify, the calibrated recovery rate of primary development using horizontal wells + volume fracturing and secondary oil recovery using conventional water injection is generally less than 15%. Tertiary oil recovery through gas drive 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, oxygen-reduced air, etc. Gas injection wells are wells that continuously inject gas into the formation to displace the formation crude oil. During the gas injection production process, gas injection wells are prone to leakage in parts such as tubing hangers, tubing threads and packers due to the high pressure and corrosiveness of the injected fluid. Once a gas injection well fails due to leakage, it is very easy to cause problems such as continuous annular pressure and corrosion of the oil and casing, endangering production safety and having a negative impact on the long-term service performance of the pipe string. However, there is currently a lack of understanding of the changes in gas flow field and oil and casing pressure under different leakage locations and leakage hole sizes in gas injection wells.

[0003] Chinese patent CN213478283U discloses a downhole oil pipe leakage simulation system, including: a pipe string simulation unit, a fluid simulation unit and a fluid collection unit. The pipe string simulation unit of this 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 facing away from the vertical section forms an outlet end; the horizontal section forms a pipe body and annulus simulation part, the curved section forms a liquid surface simulation part, and the outlet end is provided with a wellhead simulation part; this patent can realize the simulation of downhole oil pipe leakage, but since oilfield gas injection wells are generally vertical wells, the annulus liquid surface in the vertical well is a horizontal plane or a nearly horizontal plane, this patent only uses a curved pipe section to fill water to simulate the horizontal annulus liquid surface, which is quite different from the actual working conditions, and it is also unable to simulate the flow field and wellhead pressure changes in the oil casing annulus after the oil pipe is instantly ruptured during the oil pipe gas drive injection process.

[0004] Chinese patent CN110469325A discloses a method for finding leaks in gas injection pipes in oil and gas fields, which can find the leakage points of gas injection pipes in real time, intuitively and accurately by inserting a plugging device into the gas injection pipe, matching downhole television, and pressurizing the casing annulus. However, the gas injection pipe leak finding method of the patent uses downhole testing tools to determine the leakage position of the suspected leaking injection well during the actual construction process. It does not belong to the indoor simulation method of oil pipe leakage in gas injection wells, and it cannot simulate the flow field and wellhead pressure changes in the oil casing annulus after the oil pipe is instantly ruptured during the oil pipe gas drive injection process, and realize the visual observation of the leakage flow field changes.

[0005] In summary, there has not yet been found an accurate indoor simulation experimental device, experimental system and corresponding experimental method for oil pipe leakage in gas injection wells to study the flow characteristics of fluid leakage in downhole oil pipes of gas injection wells and the changes in wellhead casing pressure. Summary of the invention

[0006] The present invention aims to address the technical problems existing in the prior art and provides an experimental device, system and method for simulating oil pipe leakage in a gas injection well. The device can be used to simulate the flow field changes in the casing annulus and the wellhead pressure changes at the moment of oil pipe rupture and leakage in the gas injection well under different casing pressure differentials. The leakage hole experimental parameters and bursting pressure are easy to adjust, and the leakage flow field changes can be observed.

[0007] In order to achieve the above technical objectives, the present invention adopts the following technical solutions:

[0008] An experimental device for simulating oil pipe leakage in a gas injection well, comprising: an oil pipe leakage simulation wellbore device and a leakage hole simulation device;

[0009] The oil pipe leakage simulation wellbore device comprises a transparent casing and an oil pipe arranged in the transparent casing; a plurality of mounting holes are opened on the oil pipe for mounting a set number of leakage hole simulation devices, and non-hole bolt plugs are installed on the remaining mounting holes for sealing;

[0010] The leakage hole simulation device is a perforated bolt plug, comprising a perforated bolt, a first gasket, a bursting disc and a perforated plug; a leakage bolt hole is provided on the perforated bolt, a first gasket and a bursting disc are installed in the leakage bolt hole to achieve hole sealing, the outer end of the leakage bolt hole is fastened to the perforated plug, and the perforated plug is provided with a leakage hole.

[0011] Furthermore, a plurality of leakage hole replacement devices are installed on the outer tube wall of the transparent sleeve, and the leakage hole replacement devices are arranged corresponding to the installation holes on the oil pipe.

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

[0013] Furthermore, the transparent casing of the oil pipe leakage simulation wellbore device includes a plurality of casing short sections, each of which is provided with flanges at both ends, and the plurality of casing short sections are connected end to end through the flanges to form the transparent casing.

[0014] Furthermore, it also includes a rotatable driving base device, and the rotatable driving base device includes: an articulated base, an articulated disk and a driving motor;

[0015] The bottom end of the transparent casing of the oil pipe leakage simulation wellbore device is connected to the hinged plate;

[0016] The hinge plate is hinged on the hinge base, and the driving motor is arranged on one side of the hinge base and drives the hinge plate;

[0017] By driving the hinged disk to rotate through the driving motor, the oil pipe leakage simulation wellbore device connected to the hinged disk can be controlled to be laid down or stood upright to simulate a horizontal wellbore or a vertical wellbore.

[0018] Furthermore, the hinged plate includes a connecting plate and a hinged leg arranged below the connecting plate; the hinged base includes a bottom plate and a hinged bracket arranged on the bottom plate; the hinged leg and the hinged bracket are hinged by two left and right hinge bolts;

[0019] A driving motor is arranged on one side of the articulated bracket, and the driving motor is connected to the articulated plate through a driving shaft and a second washer.

[0020] Meanwhile, the present invention provides an experimental system for simulating oil pipe leakage in a gas injection well, comprising the experimental device as described in any one of the above items, and also comprising a gas injection circulation system, a nitrogen purge module, a gas absorption module and an annulus protection liquid level control module;

[0021] The gas injection circulation system is a closed circulation pipeline consisting of an injection pipeline, an experimental device for simulating oil pipe leakage in a gas injection well, and a return pipeline;

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

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

[0024] A third valve and a gas absorption processing container are connected to the pipeline between the second valve and the injection pipeline, and the third valve and the gas absorption processing container constitute the gas absorption module;

[0025] The experimental device for simulating oil pipe leakage in a gas injection well is also connected to a centrifugal pump, which is connected to an annulus protection liquid device, and a fourth valve is arranged on the pipeline between the centrifugal pump and the annulus protection liquid device. The centrifugal pump, the fourth valve and the annulus protection liquid device constitute the annulus protection liquid level control module.

[0026] Furthermore, a gas dye is added to the experimental gas cylinder to dye the gas in the experimental gas cylinder.

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

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

[0029] Furthermore, a high-speed camera is included to photograph the flow field changes in the oil casing annulus during the oil pipe gas injection process.

[0030] In addition, the present invention also provides an experimental method for simulating oil pipe leakage in a gas injection well, which is implemented using the experimental system as described in any one of the above items, and the method comprises the following steps:

[0031] Step S1: Use nitrogen to perform air tightness test on the system circulation pipeline and exhaust the air;

[0032] Step S2: close the inlet valve, open the experimental gas cylinder and the delivery pump, inject gas into the liquid storage tank, and use the temperature regulating device to adjust the gas temperature to generate gas with the temperature and pressure set in the experiment;

[0033] Step S3: Open the inlet valve and close the outlet valve, and inject the gas with adjusted temperature and pressure into the oil pipe leakage simulation wellbore device of the experimental device simulating the oil pipe leakage of the gas injection well. When the gas pressure in the oil pipe of the oil pipe leakage simulation wellbore device reaches the rupture pressure of the bursting disc, the gas leaks into the annulus through the leakage hole on the oil pipe simulation device;

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

[0035] 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, and release the gas pressure in the gas circulation system into the gas absorption processing container after filtering through the filter;

[0036] Step S6: After the pressure is released, the number, installation position, leakage hole diameter and pressure grade type of 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 is over, close the experimental gas cylinder, open the nitrogen cylinder, the gas injection circulation system and the gas absorption processing container, use nitrogen to purge the residual gas in the experimental system pipeline, and use the gas absorption processing container to treat the residual gas; after all the residual gas in the system is discharged, close the nitrogen cylinder and the gas absorption processing container, and seal the experimental system.

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

[0039] (1) The present invention provides an experimental device for simulating oil pipe leakage in a gas injection well. The present invention provides a plurality of mounting holes on the oil pipe of the oil pipe leakage simulation wellbore device. The mounting holes are used to install a leakage hole simulation device. The leakage hole simulation device is a bolt plug with a hole. A leakage hole is opened on the outer end side of the leakage hole, and the interior is sealed by a bursting disc. When the gas pressure in the oil pipe reaches the bursting pressure of the bursting disc, the gas leaks into the annulus through the leakage hole on the leakage hole simulation device on the oil pipe, thereby simulating the flow field change in the oil casing annulus and the wellhead pressure change after the oil pipe is instantly ruptured and leaked during the oil pipe gas drive injection process. The simulation device can be visualized and the leakage flow field can be visualized through the transparent casing. The present invention has the advantages of being able to simulate the instantaneous working conditions of oil pipe rupture leakage, simple adjustment of leakage hole experimental parameters (adjustment of the installation position, number and leakage hole diameter of the leakage hole simulation device) and bursting pressure (replacement of the bursting disc), and observable leakage flow field changes.

[0040] (2) The present invention provides an experimental device for simulating oil pipe leakage in a gas injection well, wherein the transparent casing is made of a plurality of casing short sections connected end to end, and can simulate wellbore devices of different lengths; the transparent casing is made of transparent organic glass, which is convenient for observing the changes in the flow field of the casing annulus caused by oil pipe leakage in the simulated wellbore device; a leakage hole replacement device is provided on the outer wall of the transparent casing, which is convenient for adjusting the installation position and installation quantity of the leakage hole simulation device, and replacing the leakage hole simulation device with bursting discs of different pressure levels and / or leakage holes of different sizes, and the adjustment and replacement operation is simple;

[0041] (3) The present invention provides an experimental device for simulating oil pipe leakage in a gas injection well, wherein a rotatable driving base device can drive a rotating hinge plate through a driving motor, thereby controlling the oil pipe leakage simulation wellbore device connected to the hinge plate to be laid down and erected, thereby simulating a horizontal wellbore or a vertical wellbore, saving manpower and improving efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 This is a schematic diagram of the overall structure of an experimental device for simulating oil pipe leakage in a gas injection well according to an embodiment of the present invention;

[0043] Figure 2 It is a structural schematic diagram of a wellbore device for simulating oil pipe leakage according to an embodiment of the present invention;

[0044] Figure 3 It is a component exploded view of a wellbore device for simulating oil pipe leakage according to an embodiment of the present invention;

[0045] Figure 4 It is a structural schematic diagram of a rotatable driving base device according to an embodiment of the present invention;

[0046] Figure 5 It is an exploded view of the components of the rotatable driving base device according to an embodiment of the present invention;

[0047] Figure 6 It is a structural schematic diagram of a leakage hole simulation device equipped with a bursting disc according to an embodiment of the present invention;

[0048] Figure 7 It is a component exploded view of a leakage hole simulation device equipped with a bursting disc according to an embodiment of the present invention;

[0049] Figure 8 The schematic diagram is a structural diagram of an experimental system for simulating oil pipe leakage in a gas injection well according to an embodiment of the present invention. DETAILED DESCRIPTION

[0050] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0051] In the description of the present invention, it is necessary to understand that the terms "coaxial", "bottom", "one end", "top", "middle", "the other end", "upper", "one side", "top", "inside", "front", "center", "both ends" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and 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 orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0052] In the present invention, unless otherwise clearly stipulated and limited, the terms such as "installation", "setting", "connection", "fixation" and "screw-on" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium; it can be the internal connection of two elements or the interaction relationship between two elements. Unless otherwise clearly defined, ordinary technicians in this field can understand the specific meanings of the above terms in the present invention according to the specific circumstances.

[0053] Example 1

[0054] Combination Figure 1-7 As shown, an embodiment of the present invention provides an experimental device for simulating oil pipe leakage in a gas injection well, comprising: 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 opened on the oil pipe 102 for mounting a set number of leakage hole simulation devices 3, and non-hole bolt plugs are installed on the remaining mounting holes 1021 for sealing;

[0056] The leakage hole simulation device 3 is a bolt plug with a hole, see Figure 6-7 As shown, it includes a bolt with a hole 301, a first gasket 302, a bursting disc 303 and a plug with a hole 304; the bolt with a hole 301 is provided with a leakage bolt hole 3011, the first gasket 302 and the bursting disc 303 are installed in the leakage bolt hole 3011 to achieve hole sealing, the outer end of the leakage bolt hole 3011 is threadedly fastened with a plug with a hole 304, and the plug with a hole 304 is provided with a leakage hole 3041.

[0057] When the gas pressure in the oil pipe reaches the bursting pressure of the bursting disc, the gas leaks into the annulus through the leakage hole on the leakage hole simulation device on the oil pipe, thereby simulating the flow field changes and wellhead pressure changes in the oil casing annulus after the instantaneous rupture and leakage of the oil pipe during the oil pipe gas drive injection process; wherein the pressure level of the bursting disc 303 and the aperture size of the leakage hole 3041 are both specifically set according to experimental requirements.

[0058] Specifically, Figure 2-3 As shown, the transparent casing 101 of the oil pipe leakage simulation wellbore device 1 includes two casing pup joints 1011, each casing pup joint 1011 is provided with flanges at both ends, and the two casing pup joints 1011 are connected by the flange in the middle to form the transparent casing 101; in some other embodiments, the number of casing pup joints can also be adjusted as needed to simulate wellbore devices of different lengths.

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

[0060] In the embodiment of the present invention, the transparent sleeve 101 is made of transparent organic glass, which is convenient for observing the leakage flow field changes of the experimental simulation device.

[0061] In an embodiment of the present invention, three leakage hole replacement devices 1012 are installed on the outer tube wall of each casing short 1011, and the leakage hole replacement devices 1012 are arranged corresponding to the mounting holes 1021 on the oil pipe 102, so as to adjust the number and position of the leakage hole simulation devices 3 on the mounting holes 1021; there are seven mounting holes 1021, and the fourth mounting hole 1021 in the middle is a spare hole.

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

[0063] like Figure 4-5 As shown, the rotatable driving base device 2 includes an articulated base 201 , an articulated disc 202 and a driving motor 203 .

[0064] The bottom end of the transparent casing 101 of the oil pipe leakage simulation wellbore device 1 is connected to the hinged plate 202 through a flange. The hinged plate 202 includes a connection plate 2021 and a hinged leg 2022 arranged below the connection plate 2021; the hinged base 201 includes a bottom plate 2011 and a hinged bracket 2012 arranged on the bottom plate 2011; the hinged leg 2022 and the hinged bracket 2012 are hinged through two left and right hinge bolts 204; a driving motor 203 is arranged on one side of the hinged bracket, and the driving motor 203 drives the hinged plate 202 through a driving shaft 205 and a second washer 206.

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

[0066] Example 2

[0067] An embodiment of the present invention provides an experimental system for simulating oil pipe leakage in a gas injection well, including the experimental device 6 for simulating oil pipe leakage in a gas injection well as described in Example 1, and further including a gas injection circulation system, a nitrogen purge module, a gas absorption module and an annulus protection liquid level control module.

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

[0069] The injection pipeline 5 is externally connected to the experimental gas cylinder 4 and the nitrogen gas cylinder 8, and the nitrogen gas cylinder 8 constitutes the nitrogen purge module;

[0070] The injection pipeline 5 is provided with a first valve 26, a liquid storage tank 11, a flow meter 12, a delivery pump 13, a high-pressure valve 14, a temperature regulating device 15 and an inlet valve 16 in sequence; the return pipeline 7 is provided with an outlet valve 27, a filter 19 and a second valve 25 in sequence;

[0071] The pipeline between the second valve 25 and the injection pipeline 5 is connected to a third valve 24 and a gas absorption processing container 9, and the third valve 24 and the gas absorption processing container 9 constitute the gas absorption module;

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

[0073] In the embodiment of the present invention, the experimental gas cylinder 4 is used to provide a gas injection source for experimental simulation, and the experimental gas cylinder 4 is two in parallel, one for use and one for backup. 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, so that the gas absorbs the gas dye and has color.

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

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

[0076] The liquid storage tank 11 on the injection pipeline 5 is used to buffer the gas, and the flow meter 12 is used to measure the injection gas flow; the delivery pump 13 is used to deliver the gas to the temperature regulating device 15 to regulate the temperature, thereby generating the temperature and pressure gas set in the experiment.

[0077] The filter 19 on the return line 7 is used to filter the impurities in the circulating gas. At the same time, in order to improve the filtering effect, two filters 19 are connected in series.

[0078] The experimental device 6 for simulating oil pipe leakage in a gas injection well is provided with a pressure sensor on the upper 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 also includes a high-speed camera for photographing the flow field changes in the oil casing annulus during the oil pipe gas drive injection process.

[0080] Example 3

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

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

[0083] The number of the leakage hole simulation device 3 is 1, which is installed on the mounting hole 1021 at the lower 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 level of the bursting piece 303 is 2MPa; the height of the annulus protection liquid is half of the height of the oil pipe leakage simulation wellbore device 1.

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

[0085] Step S1: Use nitrogen to perform air tightness test on the system circulation pipeline and exhaust the air;

[0086] Step S2: close the inlet valve 16, open the experimental gas cylinder 4 and the delivery pump 13, inject gas into the liquid storage tank 11, and use the temperature regulating device 15 to adjust the gas temperature, so as to generate gas with the temperature and pressure set in the experiment;

[0087] Step S3: Open the inlet valve 16, close the outlet valve 27, and inject the gas with adjusted temperature and pressure into the oil pipe leakage simulation wellbore device 1 of the experimental device 6 for simulating oil pipe leakage in 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 leaks into the annulus through the leakage hole 3041 on the leakage hole simulation device 3 on the oil pipe 102;

[0088] Step S4: using a high-speed camera to capture the flow field changes in the casing annulus at the moment of gas leakage; at the same time, through the pressure sensor set at the upper end of the tubing leakage simulation wellbore device 1, monitor and collect the wellhead pressure change data from the initial injection of gas to the stabilization of the casing pressure difference;

[0089] Step S5: close the experimental gas cylinder 4, the first valve 26, the delivery pump 13 and the inlet valve 16, open the outlet valve 27, the second valve 25 and the third valve 24, and release the gas pressure in the gas circulation system into the gas absorption processing container 9 after filtering through the filter 19;

[0090] Step S6: After the pressure is released, the number, installation position, leakage hole diameter and type of pressure grade of the bursting disc used 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 over, close the experimental gas cylinder 4, open the nitrogen cylinder 8, the gas injection circulation system and the gas absorption processing container 9, use nitrogen to purge the residual gas in the experimental system pipeline, and use the gas absorption processing container 9 to treat the residual gas; after all the residual gas in the system is discharged, close the nitrogen cylinder 8 and the gas absorption processing container 9, and realize the sealing of the experimental system by nitrogen to avoid corrosion damage to the pipeline equipment.

[0092] The above description is only an embodiment of the present invention and is not intended to limit the present invention. Any modification, equivalent replacement and improvement made within the application scope of the present invention shall be included in the protection scope of the present invention.

Claims

1. An experimental device for simulating oil pipe leakage in a gas injection well, characterized in that: include: Oil pipe leakage simulation wellbore device and leakage hole simulation device; The oil pipe leakage simulation wellbore device comprises a transparent casing and an oil pipe arranged in the transparent casing; a plurality of mounting holes are opened on the oil pipe for mounting a set number of leakage hole simulation devices, and non-hole bolt plugs are installed on the remaining mounting holes for sealing; The leakage hole simulation device is a perforated bolt plug, comprising a perforated bolt, a first gasket, a bursting disc and a perforated plug; a leakage bolt hole is provided on the perforated bolt, a first gasket and a bursting disc are installed in the leakage bolt hole to achieve hole sealing, the outer end of the leakage bolt hole is fastened to the perforated plug, and the perforated plug is provided with a leakage hole.

2. The experimental device according to claim 1, characterized in that: A plurality of leakage hole replacement devices are installed on the outer tube wall of the transparent sleeve, and the leakage hole replacement devices are arranged corresponding to the installation holes on the oil pipe.

3. The experimental device according to claim 2, characterized in that: The leakage hole replacement device comprises a boss arranged on the outer tube wall of the transparent sleeve; the boss is a hollow cylindrical structure, and the end side of the boss is connected to a cover plate through a flange for sealing.

4. The experimental device according to claim 1, characterized in that: The transparent casing of the oil pipe leakage simulation wellbore device includes a plurality of casing short sections, each of which is provided with flanges at both ends, and the plurality of casing short sections are connected end to end through the flanges to form the transparent casing.

5. The experimental device according to any one of claims 1 to 4, characterized in that: Also included is a rotatable driving base device, the rotatable driving base device comprising: an articulated base, an articulated disk and a driving motor; The bottom end of the transparent casing of the oil pipe leakage simulation wellbore device is connected to the hinged plate; The hinge plate is hinged on the hinge base, and the driving motor is arranged on one side of the hinge base and drives the hinge plate; By driving the hinged disk to rotate through the driving motor, the oil pipe leakage simulation wellbore device connected to the hinged disk can be controlled to be laid down or stood upright to simulate a horizontal wellbore or a vertical wellbore.

6. The experimental device according to claim 5, characterized in that: The hinge plate includes a connecting plate and a hinged leg arranged below the connecting plate; the hinged base includes a bottom plate and a hinged bracket arranged on the bottom plate; the hinged leg and the hinged bracket are hinged by two left and right hinge bolts; A driving motor is arranged on one side of the articulated bracket, and the driving motor is connected to the articulated plate through a driving shaft and a second washer.

7. An experimental system for simulating oil pipe leakage in a gas injection well, comprising the experimental device according to any one of claims 1 to 6, characterized in that: It also includes a gas injection circulation system, a nitrogen purge module, a gas absorption module and an annular protection liquid level control module; The gas injection circulation system is a closed circulation pipeline consisting of an injection pipeline, an experimental device for simulating oil pipe leakage in a gas injection well, and a return pipeline; The injection pipeline is externally connected to an experimental gas cylinder and a nitrogen gas cylinder, and the nitrogen gas cylinder constitutes the nitrogen purge module; The injection pipeline is provided with a first valve, a liquid storage tank, a flow meter, a delivery pump, a high-pressure valve, a temperature regulating device and an inlet valve in sequence; the return pipeline is provided with an outlet valve, a filter and a second valve in sequence; A third valve and a gas absorption processing container are connected to the pipeline between the second valve and the injection pipeline, and the third valve and the gas absorption processing container constitute the gas absorption module; The experimental device for simulating oil pipe leakage in a gas injection well is also connected to a centrifugal pump, which is connected to an annulus protection liquid device, and a fourth valve is arranged on the pipeline between the centrifugal pump and the annulus protection liquid device. The centrifugal pump, the fourth valve and the annulus protection liquid device constitute the annulus protection liquid level control module.

8. The experimental system according to claim 7, characterized in that: A gas dye is added into the experimental gas cylinder to dye the gas in the experimental gas cylinder.

9. The experimental system according to claim 8, characterized in that: The nitrogen gas cylinder and the experimental gas cylinder are connected in parallel to a collective gas injection pipeline, and the collective gas injection pipeline is connected to the injection pipeline.

10. The experimental system according to claim 7, characterized in that: The experimental device for simulating oil pipe leakage in a gas injection well is provided with a pressure sensor at the upper end of the oil pipe leakage simulation wellbore device, which is used to monitor the wellhead pressure change of the oil pipe leakage simulation wellbore device.

11. The experimental system according to claim 7, characterized in that: A high-speed camera is also included to capture the flow field changes in the oil casing annulus during the gas injection process in the oil pipe.

12. An experimental method for simulating oil pipe leakage in a gas injection well, implemented using the experimental system according to any one of claims 7 to 11, characterized in that: The method comprises the following steps: Step S1: Use nitrogen to perform air tightness test on the system circulation pipeline and exhaust the air; Step S2: close the inlet valve, open the experimental gas cylinder and the delivery pump, inject gas into the liquid storage tank, and use the temperature regulating device to adjust the gas temperature to generate gas with the temperature and pressure set in the experiment; Step S3: Open the inlet valve and close the outlet valve, and inject the gas with adjusted temperature and pressure into the oil pipe leakage simulation wellbore device of the experimental device simulating the oil pipe leakage of the gas injection well. When the gas pressure in the oil pipe of the oil pipe leakage simulation wellbore device reaches the rupture pressure of the bursting disc, the gas leaks into the annulus through the leakage hole on the oil pipe simulation device; Step S4: using a high-speed camera to capture the flow field changes in the casing annulus at the moment of gas leakage; at the same time, using a pressure sensor set at the upper end of the tubing leakage simulation wellbore device to monitor and collect wellhead pressure change data from the initial injection of gas to the stabilization of the casing pressure difference; 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, and release the gas pressure in the gas circulation system into the gas absorption processing container after filtering through the filter; Step S6: After the pressure is released, the number, installation position, leakage hole diameter and pressure grade type of the leakage hole simulation device are adjusted, and steps S1-S5 are repeated to complete the leakage simulation experiment under different experimental conditions; Step S7: After the experiment is over, close the experimental gas cylinder, open the nitrogen cylinder, the gas injection circulation system and the gas absorption processing container, use nitrogen to purge the residual gas in the experimental system pipeline, and use the gas absorption processing container to treat the residual gas; after all the residual gas in the system is discharged, close the nitrogen cylinder and the gas absorption processing container, and seal the experimental system.

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