A method for producing gas by sealing, reducing pressure and draining water at the wellhead of a gas well

Abstract

The present invention relates to the field of natural gas production technology, and in particular to a gas wellhead sealed pressure-reducing and water-draining gas production method, including a connecting device, determining a working mode, a starting process, and switching working modes. The connecting device connects the reagent injection system to the target gas well and connects the gas collection station connection structure to the gas collection station; determines the working mode, determines whether to select the auxiliary liquid drainage mode or the gas collection station gas collection mode; starts the process, opens the corresponding working channel through the valve control system, and operates the high-pressure sealed composite water-draining and gas production device according to the determined working mode; switches the working mode, observes the gas production of the target gas well, and switches between the auxiliary liquid drainage mode and the gas collection station gas collection mode through the valve control system according to the gas production situation. This technical solution combines the water-draining and gas production process, sets two working modes, and switches between the two working modes to avoid resource waste and reduce environmental pollution to a great extent.

Description

Technical Field

[0001] The present invention relates to the technical field of natural gas production, and in particular to a method for producing gas at a gas well head with sealed pressure reduction and water drainage. Background Art

[0002] During the production process of water-producing gas wells, the wellbore pressure loss continues to increase due to the reduction in the gas well's liquid carrying capacity. The bottomhole liquid will continue to accumulate, which in turn drives the wellbore pressure loss to continue to increase, causing the production well to gradually become an intermittent production well, and finally become a flooded well, resulting in shutdown, seriously affecting the gas well's productivity. To address this situation, based on the critical flow drainage principle, there are currently two common methods. From the surface process, compressor boosting is used in the gas gathering station to reduce pipeline back pressure and thus achieve the purpose of reducing wellhead pressure; or single well boosting is used at the wellhead to directly reduce wellhead back pressure, or direct blowdown is adopted at the wellhead. From the gas well production system, optimized production methods such as shut-in and re-pressurization, intermittent production, etc. are used to achieve the continuation of the gas well production cycle. From the water drainage gas production process method, foam drainage gas production technology or plunger technology are mainly used to achieve liquid-carrying production in gas wells.

[0003] The current gas wellhead pressure reduction methods are relatively simple and independent, especially there is no effective corresponding solution for different types of gas wells, and the scope of application is limited. The main manifestations are:

[0004] 1) Without the use of drainage and gas recovery technology, conventional wellhead venting can only achieve the purpose of pressure reduction for a short time;

[0005] 2) The venting process and procedures are simple, and wellhead pressure reduction alone cannot restore normal liquid-carrying production in some complex gas wells;

[0006] 3) The pressure reduction method used in the gas wells lacked data analysis support and relied solely on experience. While this initially achieved the pressure reduction goal, it did not achieve continuous liquid-carrying production in the gas wells.

[0007] 4) After taking pressure reduction measures, direct release will result in incomplete gas-liquid separation and incomplete venting and combustion of natural gas, causing environmental pollution;

[0008] 5) The processing method of natural gas after separation is single, with low safety and inability to cope with emergencies. Summary of the Invention

[0009] In view of the deficiencies in the prior art, the present invention provides a method for gas production by closed pressure reduction and drainage at the wellhead of a gas well. Based on the critical flow principle, the method uses a closed pressure reduction process at the wellhead in combination with a foam drainage and gas production technology. By accurately collecting real-time data such as pressure, temperature, and output, different discharge processes and drainage and gas production process methods are flexibly selected through background data analysis to reduce the critical flow of continuous liquid carrying in water-producing gas wells, solve the production problems of intermittent production wells and flooded and shut-down wells, restore the normal water-carrying production of gas wells, and improve the recovery rate of single wells. At the same time, through different process conversions, natural gas can be promptly discharged or enter the ground process to avoid waste of resources.

[0010] This is achieved specifically through the following technical solutions:

[0011] First of all, based on the purpose, this technical solution provides a high-pressure closed composite drainage and gas production device (hereinafter referred to as the equipment), which includes a skid-mounted bracket, on which are arranged a reagent injection system, a gas-liquid separation and drainage system, a blowout ignition system and a pipeline system including several connecting pipelines; the reagent injection system, the gas-liquid separation and drainage system and the blowout ignition system are connected in sequence through connecting pipelines; the pipeline system is connected to a temperature measuring device, a valve control system, a pressure measuring system and a flow detection device; a gas collection station connection structure is connected between the reagent injection system and the gas-liquid separation and drainage system.

[0012] Specifically, the chemical injection system includes a rod thrower, a defoaming balancing tank and a wellhead Christmas tree; the rod thrower is sealed and connected to the wellhead Christmas tree, and a pressure relief valve is connected between the rod thrower and the wellhead Christmas tree; the defoaming balancing tank is connected to the connecting pipeline at the fluid outlet end of the wellhead Christmas tree.

[0013] Specifically, the Christmas tree is also provided with an annulus injection port with a valve switch.

[0014] Specifically, the gas-liquid separation and drainage system includes a gas-liquid cyclone separator, a mist collector, a steam trap and a water storage device which are conductively connected via a connecting pipeline; the gas-liquid mixed inlet end I of the gas-liquid cyclone separator is sealed and conductively connected to the fluid outlet end of the wellhead oil production tree, the gas-liquid mixed outlet end I of the gas-liquid cyclone separator is sealed and conductively connected to the gas-liquid mixed inlet end II of the mist collector, the liquid outlet end I of the gas-liquid cyclone separator is sealed and conductively connected to the first inlet end of the steam trap; the liquid outlet end II of the mist collector is sealed and conductively connected to the second inlet end of the steam trap, the gas outlet end of the mist collector is sealed and conductively connected to the air inlet end of the blowdown ignition system; and the water storage device is sealed and conductively connected to the liquid outlet end of the steam trap.

[0015] Specifically, the flow detection device includes an orifice flow meter connected between the mist catcher and the blowdown ignition system, and a liquid flow meter arranged on the gas-liquid cyclone separator.

[0016] Specifically, the water storage device includes a water tank connected to the liquid outlet of the steam trap through a connecting pipeline; a flap level gauge is provided inside the water tank; a breathing port and a sewage outlet are opened on the water tank, and a throttling stop valve is provided at the sewage outlet.

[0017] Specifically, the valve control system includes a pressure-controlled regulating valve connected between the wellhead Christmas tree and the defoaming balance tank, a ball valve connected between the mist catcher and the steam trap, and a needle valve connected between the mist catcher and the orifice flowmeter.

[0018] Specifically, the valve control system further includes a first safety valve connected between the gas-liquid cyclone separator and the mist catcher and a second safety valve connected between the gas-liquid cyclone separator and the steam trap.

[0019] Specifically, the pressure measurement system includes a first pressure gauge connected between the defoaming balance tank and the gas gathering station connection structure, a second pressure gauge connected between the mist collector and the needle valve, a third pressure gauge connected between the needle valve and the orifice flowmeter, and a fourth pressure gauge arranged on the steam trap.

[0020] Specifically, the temperature measuring device is arranged on the connecting pipeline at the gas outlet end of the mist catcher.

[0021] Specifically, the blowout ignition system includes a first gate valve, a flame arrester and a torch device which are sequentially connected; the input end of the first gate valve serves as the air inlet end of the blowout ignition system.

[0022] Specifically, the gas gathering station connection structure includes a gas gathering station interface and a ground pipeline. The gas gathering station interface is connected to the gas-liquid mixing inlet port I of the gas-liquid cyclone separator through the ground pipeline. A second gate valve is provided on the ground pipeline.

[0023] Specifically, a control circuit is also arranged on the skid-mounted bracket; the temperature measuring device, pressure measuring system and flow detection device are respectively connected to the computer console for communication via the control circuit.

[0024] Based on the aforementioned high-pressure sealed composite drainage and gas production device, the present technical solution provides a gas wellhead sealed pressure reduction drainage and gas production method, that is, using the aforementioned high-pressure sealed composite drainage and gas production device to perform drainage and gas production work, the drainage and gas production work includes connecting the device, determining the working mode, starting the process and switching the working mode;

[0025] The connecting device closes the valve control system of the high-pressure closed composite drainage gas production device, connects the reagent injection system to the target gas well, and connects the gas gathering station connection structure to the gas gathering station;

[0026] The working mode is determined by selecting the auxiliary liquid drainage mode or the gas gathering station gas gathering mode according to the gas production conditions of the target gas well;

[0027] The startup process, based on the determined working mode, opens the corresponding working channel through the valve control system and operates the high-pressure closed composite drainage and gas production device according to the determined working mode; wherein, the working channel of the auxiliary drainage mode is from the reagent injection system, through the gas-liquid separation and drainage system, to the blowdown ignition system; the working channel of the gas gathering station mode is from the reagent injection system to the gas gathering station;

[0028] The switching working mode is based on the current working mode, observing the gas production of the target gas well, and switching between the auxiliary drainage mode and the gas gathering station gas gathering mode through the valve control system according to the gas production situation.

[0029] Preferably, in the process of determining the working mode, if the target gas well meets the conditions for continuous liquid-carrying production, the gas gathering station gas gathering mode is selected; if the target gas well does not meet the conditions for continuous liquid-carrying production, the auxiliary liquid drainage mode is selected.

[0030] Preferably, when the determined working mode is the auxiliary drainage mode, the startup process includes the following steps:

[0031] Throwing foaming objects into the target gas well through the reagent injection system;

[0032] The valve control system opens the working channel of the auxiliary drainage mode, allowing the fluid in the target gas well to flow from the chemical injection system into the gas-liquid separation drainage system. During this period, the defoaming balance tank in the chemical injection system is used to defoam the passing fluid.

[0033] Use the gas-liquid separation and drainage system to separate the fluid into gas and liquid;

[0034] The liquid obtained by gas-liquid separation is collected by using a liquid storage device in the gas-liquid separation and drainage system;

[0035] The gas obtained from gas-liquid separation is burned using a blowdown ignition system.

[0036] Preferably, opening the working channel in the auxiliary liquid discharge mode includes opening the pressure-controlled regulating valve, the first safety valve, the second safety valve, the ball valve, the needle valve and the first gate valve in the valve control system.

[0037] Preferably, the foaming object is a foaming rod and / or a foaming agent.

[0038] Preferably, during the gas-liquid separation process, the gas-liquid cyclone separator in the gas-liquid separation and drainage system is used to perform preliminary gas-liquid separation on the inflowing fluid, the mist collector in the gas-liquid separation and drainage system is used to perform secondary gas-liquid fine separation on the gas phase of the gas-liquid cyclone separator, and the hydrophobic device in the gas-liquid separation and drainage system is used to buffer the liquid phases of the gas-liquid cyclone separator and the mist collector.

[0039] Preferably, the switching working mode includes the following two cases:

[0040] If the current working mode is the gas gathering mode of the gas gathering station, the gas gathering situation of the gas gathering station is used to determine whether the target gas well is in a continuous liquid-carrying production state; if so, the gas gathering mode of the gas gathering station is maintained; if not, the working channel of the gas gathering mode of the gas gathering station is closed through the valve control system, the working channel of the auxiliary drainage mode is opened, and a foaming object is injected into the target gas well through the reagent injection system;

[0041] If the current working mode is auxiliary discharge mode, the switching working mode includes the following steps:

[0042] The pressure and gas production information of the corresponding fluid inside the high-pressure closed composite drainage and gas production device are obtained through the pressure measurement system and flow detection device;

[0043] According to the pressure changes, timely adjust the target gas well wellhead flow rate and the opening of the needle valve and ball valve in the valve control system;

[0044] The pressure and gas production information obtained are used to infer whether the target gas well meets the conditions for continuous liquid-carrying production. If so, the valve control system closes the working channel of the auxiliary drainage mode and opens the working channel of the gas gathering station gas gathering mode. If not, the auxiliary drainage mode is maintained.

[0045] Preferably, the process of connecting the device also includes laying out a control circuit, and connecting the temperature measuring device, the pressure measuring system and the flow detection device to the computer console through the control circuit.

[0046] Preferably, during the process of switching the working mode, if the current working mode is the auxiliary drainage mode, the pressure and gas production data of the corresponding fluid inside the high-pressure closed composite drainage and gas production device are remotely obtained through the computer console, and the obtained pressure data and gas production data are converted into coordinate curve graphs respectively using the computer console.

[0047] Preferably, the drainage and gas production work further includes pressure test, adjustment and calibration, and the pressure test, adjustment and calibration includes the following steps:

[0048] S1, sets the trip threshold for the pressure-controlled regulating valve;

[0049] S2, filling water into the high-pressure closed composite drainage and gas production device to make the internal pressure reach 0.8MPa;

[0050] S3, observe whether the pressure-controlled regulating valve has tripped; if so, take remedial measures for the pressure-controlled regulating valve, including repair, replacement, and resetting the trip threshold, and then return to step S2; if not, proceed to step S4;

[0051] S4, wait for 10 minutes and observe whether there is any leakage in the high-pressure sealed composite drainage and gas production device; if there is, repair the leak and return to step S2; if not, go to step S5;

[0052] S5, filling water into the high-pressure closed composite drainage and gas production device until the internal pressure reaches 3 MPa;

[0053] S6, observe whether the pressure-controlled regulating valve trips; if so, take remedial measures for the pressure-controlled regulating valve, including repair, replacement, and resetting the trip threshold, and then return to step S2; if not, proceed to step S7;

[0054] S7, wait for 30 minutes and observe whether there is any leakage in the high-pressure sealed composite drainage and gas production device; if there is, repair the leak and return to step S2; if not, go to step S8;

[0055] S8, filling water into the high-pressure closed composite drainage and gas production device until the internal pressure reaches 6 MPa;

[0056] S9, observe whether the pressure-controlled regulating valve has tripped; if so, take remedial measures for the pressure-controlled regulating valve, including repair, replacement, and resetting the trip threshold, and then return to step S2; if not, proceed to step S10;

[0057] S10, wait for 30 minutes and observe whether the high-pressure sealed composite drainage and gas production device has any leakage; if yes, repair the leakage location and return to step S2; if not, the pressure test adjustment and calibration is completed.

[0058] Beneficial effects brought by this technical solution:

[0059] 1) This technical solution combines the drainage gas production process and sets two working modes. By switching between the two working modes, the auxiliary drainage mode can be used to achieve long-term pressure reduction and drainage at the wellhead. By observing the changes in the gas production of the target gas well, the gas gathering mode of the gas gathering station can be switched in time, which greatly avoids resource waste and reduces environmental pollution.

[0060] 2) The auxiliary drainage mode in this technical solution is combined with the foam drainage gas production process, which can effectively discharge the accumulated liquid in the wellbore, providing great help in activating or restoring the expected production capacity of the gas well; secondly, the gas-liquid cyclone separator is used in combination with the mist collector. The fluid discharged from the gas wellhead is separated once in the gas-liquid cyclone separator, and the mist mixed fluid obtained is subjected to a second fine separation in the mist collector, which can make the gas-liquid separation more thorough, and the natural gas will burn more fully in the flare device, thereby greatly avoiding environmental pollution; thirdly, the use of a steam trap to buffer the liquid phase of the gas-liquid cyclone separator and the mist collector can achieve pressure-free separation and drainage at the tail, avoiding impact damage to the liquid storage tank.

[0061] 3) This technical solution uses pressure and gas production data as an analysis basis, and the most reasonable working mode can be selected through data analysis. With actual data as support, it can ensure that when switching to the gas gathering station gas gathering mode, the target gas well is in a continuous liquid-carrying production state.

[0062] 4) This technical solution realizes remote communication between the equipment and the computer console by laying out the control circuit. During measurement, the data is directly read into the computer console, completing automatic reading and generating a real-time change curve, which facilitates real-time analysis and adjustment of the work system. At the same time, it avoids the danger of construction workers entering the high-voltage area to read data, and can also avoid errors caused by manual reading.

[0063] 5) This technical solution utilizes a pressure-controlled regulating valve to ensure that when the pressure of the fluid discharged from the target gas wellhead surges above the tripping threshold, the valve senses the pressure and automatically trips. This timely closure ensures that the fluid pressure does not damage the equipment, ensuring the safety of construction personnel. Later, the valve can be slowly opened manually to restore normal equipment operation. Passing the pressure test and calibration ensures the safety and reliability of this technical solution. Furthermore, reaching the maximum operating pressure in three stages prevents excessive pressure fluctuations from turning small leaks into large ones, or even rupturing the equipment and threatening the safety of personnel.

[0064] 6) This technical solution can convert intermittent wells into continuous production wells and resume production of flooded and shut-down wells, achieving a daily gas production increase of more than 1,000 m3 / d. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] The foregoing and following detailed description of the present invention will become more apparent when read in conjunction with the following drawings, in which:

[0066] Figure 1 This is a schematic diagram of the front structure of the equipment used in this technical solution;

[0067] Figure 2 This is a schematic diagram of the top view of the equipment used in this technical solution;

[0068] Figure 3 This is a schematic diagram of the left side structure of the equipment used in this technical solution;

[0069] Figure 4 This is a schematic diagram of the right side structure of the equipment used in this technical solution;

[0070] Figure 5 This is the structural principle diagram of the equipment used in this technical solution.

[0071] In the picture:

[0072] 1. Skid-mounted bracket; 2. Rod ejector; 3. Pressure-controlled regulating valve; 4. Defoaming balance tank; 5. Wellhead Christmas tree; 5.1. Annular injection port; 5.2. Fluid outlet; 6. Pressure relief valve; 7. Gas-liquid cyclone separator; 7.1. Liquid outlet port I; 7.2. Gas-liquid mixed outlet port I; 7.3. Gas-liquid mixed inlet port I; 8. Mist collector; 8.1. Gas-liquid mixed inlet port II; 8.2. Liquid outlet port II; 8.3. Gas outlet port; 9. Steam trap; 9.1. First inlet port; 9.2. Second inlet port; 9.3. Liquid outlet port; 10. Orifice flowmeter; 11. Liquid flowmeter; 12. Water storage Box; 12.1, breathing port; 12.2, sewage outlet; 13, flap level gauge; 14, first safety valve; 15, second safety valve; 16, ball valve; 17, needle valve; 18, first pressure gauge; 19, second pressure gauge; 20, third pressure gauge; 21, fourth pressure gauge; 22, temperature measuring device; 23, computer console; 24, first gate valve; 25, flame arrester; 26, flare device; 26.1, flare head; 26.2, flare base; 27, gas gathering station interface; 28, second gate valve; 29, control circuit; 30, throttling stop valve; 31, connecting pipeline; 32, valve switch. DETAILED DESCRIPTION

[0073] In order to make the purpose, technical solutions and advantages of the invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with the drawings in the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments.

[0074] Therefore, the following detailed description of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort shall fall within the scope of protection of the present invention.

[0075] Example 1

[0076] This embodiment provides a method for depressurizing and draining gas at the wellhead of a gas well. As a preferred implementation scheme of this technical solution, a high-pressure closed composite drainage and gas production device provided by this technical solution is used to perform drainage and gas production work; the drainage and gas production work includes connecting the device, determining the working mode, starting the process and switching the working mode.

[0077] Connect the device, close the valve control system of the high-pressure, sealed, composite drainage gas production device, connect the chemical injection system to the target gas well (the currently operating gas well), and connect the gas gathering station connection structure to the gas gathering station. Specifically, close the pressure-controlled regulating valve 3, pressure relief valve 6, first safety valve 14, second safety valve 15, ball valve 16, needle valve 17, first gate valve 24, second gate valve 28, throttling stop valve 30, and valve switch 32 in the valve control system; connect the wellhead Christmas tree 5 in the chemical injection system to the wellhead of the target gas well; and connect to the gas gathering station through the gas gathering station interface 27 in the gas gathering station connection structure.

[0078] Determine the operating mode and, based on the target gas well's gas production conditions, select either the auxiliary liquid drainage mode or the gas gathering station gas gathering mode. Specifically, if the target gas well meets the conditions for continuous liquid-carrying production, the gas gathering station gas gathering mode is selected; if the target gas well does not meet the conditions for continuous liquid-carrying production, the auxiliary liquid drainage mode is selected.

[0079] The startup process opens the corresponding working channel through the valve control system based on the determined working mode, and operates the high-pressure closed composite drainage and gas production device according to the determined working mode; among them, the working channel of the auxiliary drainage mode is from the reagent injection system, through the gas-liquid separation and drainage system, to the blowdown ignition system; the working channel of the gas gathering station gas gathering mode is from the reagent injection system to the gas gathering station.

[0080] Switch the working mode. Based on the current working mode, observe the gas production of the target gas well. According to the gas production, switch between the auxiliary drainage mode and the gas gathering station gas gathering mode through the valve control system.

[0081] This technical solution combines the drainage gas production process and sets up two working modes. By switching between the two working modes, the auxiliary drainage mode can be used to achieve long-term pressure reduction and drainage at the wellhead. By observing the changes in the gas production of the target gas well, the gas gathering mode of the gas gathering station can be switched in time, thereby greatly avoiding resource waste and reducing environmental pollution.

[0082] Example 2

[0083] This embodiment provides a method for gas production by closed pressure reduction and water drainage at the wellhead of a gas well, which is a preferred implementation scheme of the present technical solution. That is, in Example 1, when the determined working mode is the gas gathering station gas gathering mode, the startup process is to open the pressure-controlled regulating valve 3 and the second gate valve 28 in the valve control system, so that the fluid flowing through the wellhead oil production tree 5 directly enters the gas gathering station.

[0084] Furthermore, when the determined working mode is the auxiliary drainage mode, the startup process includes the following steps:

[0085] S1, injecting a foaming object into the target gas well through the agent injection system; further, the foaming object is a foaming rod injected through the rod injector 2 and / or a foaming agent injected through the annulus injection port 5.1, and the type of foaming object used can be selected according to the internal environment of the target gas well;

[0086] S2: Open the working channel of the auxiliary drainage mode through the valve control system, specifically opening the pressure-controlled regulating valve 3, the first safety valve 14, the second safety valve 15, the ball valve 16, the needle valve 17, and the first gate valve 24 in the valve control system; the fluid in the target gas well enters the gas-liquid separation drainage system from the reagent injection system. During this period, the defoaming balance tank 4 in the reagent injection system is used to defoam the passing fluid to eliminate the impact of foam on the separation effect;

[0087] S3, using the gas-liquid separation and drainage system to perform gas-liquid separation on the fluid. During this process, further, using the gas-liquid cyclone separator 7 in the gas-liquid separation and drainage system to perform preliminary gas-liquid separation on the inflowing fluid, using the mist catcher 8 in the gas-liquid separation and drainage system to perform secondary gas-liquid fine separation on the gas phase of the gas-liquid cyclone separator 7, and using the steam trap 9 in the gas-liquid separation and drainage system to buffer the liquid phases of the gas-liquid cyclone separator 7 and the mist catcher 8;

[0088] S4, using the liquid storage device in the gas-liquid separation and drainage system to collect the liquid obtained by gas-liquid separation; further, the liquid level inside the water storage tank 12 can be observed by the flap level gauge 13 in the liquid storage device. When the liquid level reaches a certain level, the liquid can be discharged through the sewage outlet 12.2 for centralized treatment, so that the equipment can continue to operate while avoiding pollution;

[0089] S5, uses the blowdown ignition system to burn the gas obtained from gas-liquid separation, greatly reducing environmental pollution.

[0090] The auxiliary drainage mode in this technical solution is combined with the foam drainage gas production process, which can effectively discharge the accumulated liquid in the wellbore, and provides great help for activating or restoring the expected production capacity of the gas well; secondly, the gas-liquid cyclone separator 7 and the mist catcher 8 are used in combination, and the fluid discharged from the gas wellhead is separated once in the gas-liquid cyclone separator 7, and the mist mixed fluid obtained is subjected to a secondary fine separation in the mist catcher 8, which can make the gas-liquid separation more thorough, and the natural gas will burn more fully in the flare device 26, thereby avoiding environmental pollution to the greatest extent; furthermore, the steam trap 9 is used to buffer the liquid phase of the gas-liquid cyclone separator 7 and the mist catcher 8, which can realize pressure-free separation and drainage at the tail, and avoid impact damage to the liquid storage tank.

[0091] Example 3

[0092] This embodiment provides a method for gas production by depressurizing and draining water at the wellhead of a gas well, which is a preferred implementation scheme of this technical solution. In Example 1, the switching working mode includes the following two situations:

[0093] The first is switching from the gas gathering station's gas gathering mode to the auxiliary drainage mode. Specifically, if the current operating mode is the gas gathering station's gas gathering mode, the system determines whether the target gas well is in continuous liquid-carrying production based on the station's gas gathering status. If so, the station maintains the gas gathering mode. If not, the valve control system closes the station's gas gathering mode operating channel, opens the auxiliary drainage mode operating channel, and injects a foaming agent into the target gas well via the reagent injection system.

[0094] The second is to switch from auxiliary drainage mode to gas gathering station mode. That is, if the current working mode is auxiliary drainage mode, switching the working mode includes the following steps:

[0095] The pressure and gas production information of the corresponding fluid inside the high-pressure closed composite drainage and gas production device are obtained through the pressure measurement system and the flow detection device. Specifically, it is necessary to obtain the pressures measured by the first pressure gauge 18, the second pressure gauge 19, the third pressure gauge 20, and the fourth pressure gauge 21, as well as the flow information (corresponding to the gas production information) measured by the orifice flowmeter 10 and the liquid flowmeter 11 respectively.

[0096] According to pressure changes, the target gas wellhead flow rate and the opening of the needle valve 17 and ball valve 16 in the valve control system are adjusted in a timely manner. For example, when the fluid pressure inside the equipment increases, it is very likely that the fluid pressure in the target gas well has increased. In this case, the target gas wellhead flow rate and the opening of the needle valve 17 and ball valve 16 need to be increased to adapt to the change in the fluid pressure inside the target gas well while ensuring that the equipment operates within a safe pressure range.

[0097] The pressure and gas production information obtained are used to infer whether the target gas well meets the conditions for continuous liquid-carrying production. If so, the valve control system closes the working channel of the auxiliary drainage mode and opens the working channel of the gas gathering station gas gathering mode. If not, the auxiliary drainage mode is maintained.

[0098] This technical solution uses pressure and gas production data as an analysis basis, and can select the most reasonable working mode through data analysis. With actual data as support, it can ensure that when switching to the gas gathering station gas gathering mode, the target gas well is in a continuous liquid-carrying production state.

[0099] Example 4

[0100] This embodiment provides a method for gas production by depressurizing and draining gas at the wellhead of a gas well. As a preferred embodiment of this technical solution, in Example 3, the connection device further includes a control circuit 29, and the temperature measuring device 22, the pressure measuring system, and the flow detection device are communicatively connected to the computer console 23 via the control circuit 29. Furthermore, during the switching of operating modes, if the current operating mode is the auxiliary liquid drainage mode, the pressure and gas production data of the corresponding fluid within the high-pressure, sealed composite drainage and gas production device are remotely obtained via the computer console 23, and the obtained pressure data and gas production data are converted into coordinate curve graphs by the computer console 23.

[0101] This technical solution realizes remote communication between the equipment and the computer console 23 by laying out the control circuit 29. During measurement, the data is directly read into the computer console 23, automatic reading is completed and a real-time change curve is generated, which facilitates real-time analysis and adjustment of the work system. At the same time, it avoids the danger caused by construction personnel entering the high-voltage area to read data, and can also avoid errors caused by manual reading.

[0102] In addition, in actual use, the temperature range that the equipment can withstand is generally 10~60℃. Therefore, the safe operating temperature range of the equipment is 5~85℃. Based on the temperature measuring device 22, the equipment temperature is detected through the computer console 23. When the temperature exceeds the safe range, the construction should be stopped in time.

[0103] Example 5

[0104] This embodiment provides a method for gas production by depressurizing and draining water at the wellhead of a gas well, which is a preferred embodiment of the present technical solution. In Example 1, the drainage and gas production work also includes pressure test, adjustment and calibration, and the pressure test, adjustment and calibration includes the following steps:

[0105] S1, sets the tripping threshold for the pressure-controlled regulating valve 3;

[0106] S2, filling water into the high-pressure closed composite drainage and gas production device to make the internal pressure reach 0.8MPa;

[0107] S3, observe whether the pressure-controlled regulating valve 3 trips; if so, take remedial measures for the pressure-controlled regulating valve 3, including repair, replacement, and resetting the trip threshold, and then return to step S2; if not, proceed to step S4;

[0108] S4, wait for 10 minutes and observe whether there is any leakage in the high-pressure sealed composite drainage and gas production device; if there is, repair the leak and return to step S2; if not, go to step S5;

[0109] S5, filling water into the high-pressure closed composite drainage and gas production device until the internal pressure reaches 3 MPa;

[0110] S6, observe whether the pressure-controlled regulating valve 3 trips; if so, take remedial measures for the pressure-controlled regulating valve 3, including repair, replacement, and resetting the trip threshold, and then return to step S2; if not, proceed to step S7;

[0111] S7, wait for 30 minutes and observe whether there is any leakage in the high-pressure sealed composite drainage and gas production device; if there is, repair the leak and return to step S2; if not, go to step S8;

[0112] S8, filling water into the high-pressure closed composite drainage and gas production device until the internal pressure reaches 6 MPa;

[0113] S9, observe whether the pressure-controlled regulating valve 3 trips; if so, take remedial measures for the pressure-controlled regulating valve 3, including repair, replacement, and resetting the trip threshold, and then return to step S2; if not, proceed to step S10;

[0114] S10, wait for 30 minutes and observe whether the high-pressure sealed composite drainage and gas production device has any leakage; if yes, repair the leakage location and return to step S2; if not, the pressure test adjustment and calibration is completed.

[0115] In actual use, the maximum pressure that the equipment can withstand is 6.3Mpa. Based on this, the safe operating pressure of the equipment is set to 0.1~6MPa. Therefore, during the pressure test, adjustment and calibration process, the equipment needs to be able to withstand a maximum pressure of 6MPa. Therefore, the tripping threshold of the pressure-controlled regulating valve 3 is set to 6MPa. That is, when the pressure of the fluid discharged from the wellhead of the target gas well increases sharply by more than 6MPa, the pressure-controlled regulating valve 3 senses the pressure and automatically trips. By closing it in time, it ensures that the fluid pressure will not cause damage to the equipment and the safety of the construction personnel. Later, by manually slowly opening the pressure-controlled regulating valve 3, the equipment can be put into normal operation. Passing the pressure test, adjustment and calibration can ensure the safety and reliability of the implementation of this technical solution; further, gradually reaching 6MPa in three stages can avoid the pressure change span being too large, turning small leaks in the equipment into large leaks, or even breaking through the equipment and threatening the safety of the personnel.

[0116] Example 6

[0117] This embodiment takes a spaced gas well as an example to provide a method for producing gas by sealing, depressurizing, and draining water at the wellhead of a gas well, which is a preferred implementation scheme of this technical solution and includes the following steps:

[0118] S1, connecting device;

[0119] S2, setting a tripping threshold for the pressure-controlled regulating valve 3, and opening the pressure-controlled regulating valve 3, the first safety valve 14, the second safety valve 15, the ball valve 16 and the needle valve 17;

[0120] S3, filling water into the high-pressure closed composite drainage and gas production device until the internal pressure reaches 0.8 MPa;

[0121] S4, observe whether the pressure-controlled regulating valve 3 trips; if so, take remedial measures for the pressure-controlled regulating valve 3, including repair, replacement, and resetting the trip threshold, and then return to step S2; if not, proceed to step S4;

[0122] S5, wait for 10 minutes and observe whether there is any leakage in the high-pressure sealed composite drainage and gas production device; if there is, repair the leak and return to step S2; if not, go to step S5;

[0123] S6, filling water into the high-pressure closed composite drainage and gas production device until the internal pressure reaches 3 MPa;

[0124] S7, observe whether the pressure-controlled regulating valve 3 trips; if so, take remedial measures for the pressure-controlled regulating valve 3, including repair, replacement, and resetting the trip threshold, and then return to step S2; if not, proceed to step S7;

[0125] S8, wait for 30 minutes and observe whether there is any leakage in the high-pressure sealed composite drainage and gas production device; if there is, repair the leak and return to step S2; if not, go to step S8;

[0126] S9, filling water into the high-pressure closed composite drainage and gas production device until the internal pressure reaches 6 MPa;

[0127] S10, observe whether the pressure-controlled regulating valve 3 trips; if so, take remedial measures for the pressure-controlled regulating valve 3, including repair, replacement, and resetting the trip threshold, and then return to step S2; if not, proceed to step S10;

[0128] S11, wait for 30 minutes and observe whether the high-pressure sealed composite drainage and gas production device has any leakage; if yes, repair the leakage location and return to step S2; if not, the pressure test adjustment and calibration is completed.

[0129] S12, open the first gate valve 24 and the breathing port 12.1 on the air storage tank;

[0130] S13, using the computer console 23 to monitor the flow rate change curves of the liquid flow meter 11 and the orifice flow meter 10 in real time, and simultaneously monitor the pressure change curves of the first pressure gauge 18, the second pressure gauge 19, the third pressure gauge 20, and the fourth pressure gauge 21. The wellhead liquid flow rate and the openings of the needle valve 17 and the ball valve 16 are adjusted in a timely manner according to the pressure changes, and an appropriate operating mode is selected according to the gas flow rate.

[0131] S14, real-time monitoring of the liquid level gauge 13 provided on the side of the liquid storage tank. When the water level exceeds a certain level, the liquid is promptly drained through the sewage outlet so that the operation can continue;

[0132] S15: If the intermittent gas well fails to achieve autonomous continuous liquid production, a foam rod is inserted into the tubing via the rod ejector 2, and the defoaming balance tank 4 is opened to inject defoaming agent to eliminate the impact of foam on the separation effect. At the same time, depending on the construction situation, it is considered whether to inject a foaming agent via the annular injection port 5.1;

[0133] S16. After the construction is completed, first close the reagent injection system, wait until the torch device 26 is extinguished, no liquid flows into the liquid outlet box, and the equipment is depressurized before disassembly.

[0134] Example 7

[0135] This embodiment takes a flooded and shut-down gas well as an example to provide a method for gas production by sealing, depressurizing, and draining water at the wellhead. As a preferred implementation scheme of this technical solution, the method includes the following steps:

[0136] S1, before construction, first throw the foaming rod into the oil pipe by throwing the rod, and inject the foaming agent through the annular injection port 5.1;

[0137] S2, connecting device;

[0138] S3, perform pressure test adjustment and calibration;

[0139] S4, open the first gate valve 24 and the breathing port 12.1 on the air storage tank;

[0140] S5, open the wellhead Christmas tree 5 to allow the discharged fluid to enter the agent injection system, and at the same time open the defoaming balance tank 4 to inject the defoaming agent;

[0141] S6, using the computer console 23 to observe the flow rate change curves of the liquid flow meter 11 and the orifice flow meter 10 in real time, and simultaneously observe the pressure change curves of the first pressure gauge 18, the second pressure gauge 19, the third pressure gauge 20, and the fourth pressure gauge 21. According to the pressure changes, the agent injection system, the liquid flow rate, the opening of the needle valve 17 and the ball valve 16 are adjusted in a timely manner, and the appropriate working mode is selected according to the gas flow rate;

[0142] S7, real-time monitoring of the liquid level gauge 13 provided on the side of the liquid storage tank. When the water level exceeds a certain level, the liquid is promptly drained through the sewage outlet so that the operation can continue;

[0143] S8, after the construction is completed, first close the reagent injection system, wait until the torch device 26 is extinguished, no liquid flows into the liquid outlet box, and the equipment is depressurized before it can be disassembled.

[0144] Example 7

[0145] In the Sulige gas field in the Ordos Basin, a typical gas well, Su 5-X1, was tested using a wellhead-sealed depressurization and water drainage process and method provided by the present invention. This method achieved significant production increases. Results showed that the well's casing pressure differential decreased by 2.1 MPa, and the average daily gas production increased from 0.15 × 10⁴ m³ / d before the test to 0.45 × 10⁴ m³ / d afterward. The average daily water production also increased from 0.2 m³ / d to 0.5 m³ / d, a 250% increase. This demonstrates that the wellhead-sealed depressurization and water drainage gas production method provided by the present invention is well-designed, safe, and reliable, and possesses practical application value.

Claims

1. A method for producing gas by depressurizing and draining water from a closed gas wellhead, characterized by: A high-pressure sealed composite drainage and gas production device is used to carry out drainage and gas production work; the high-pressure sealed composite drainage and gas production device includes a reagent injection system, a gas-liquid separation and drainage system and a blowdown ignition system which are connected in sequence through a pipeline system, and a temperature measuring device (22), a valve control system, a pressure measuring system and a flow detection device are connected in the pipeline system; a gas collection station connection structure is connected between the reagent injection system and the gas-liquid separation and drainage system; the gas-liquid separation and drainage system includes a gas-liquid cyclone separator, a mist catcher, a water trap and a water storage device which are connected through a connecting pipeline; the gas-liquid mixing device of the gas-liquid cyclone separator is connected to the gas-liquid mixing device of the gas-liquid mixing device. The outlet end I is sealed and connected to the gas-liquid mixed inlet end II of the mist collector, and the liquid outlet end I of the gas-liquid cyclone separator is sealed and connected to the first inlet end of the steam trap; the liquid outlet end II of the mist collector is sealed and connected to the second inlet end of the steam trap; the flow detection device includes an orifice flow meter connected between the mist collector and the blowdown ignition system; the valve control system includes a ball valve (16) connected between the mist collector and the steam trap and a needle valve (17) connected between the mist collector and the orifice flow meter; the drainage and gas production work includes connecting the device, determining the working mode, starting the process and switching the working mode; The connecting device closes the valve control system of the high-pressure closed composite drainage gas production device, connects the reagent injection system to the target gas well, and connects the gas gathering station connection structure to the gas gathering station; The working mode is determined by selecting the auxiliary liquid drainage mode or the gas gathering station gas gathering mode according to the gas production conditions of the target gas well; The startup process, based on the determined working mode, opens the corresponding working channel through the valve control system and operates the high-pressure closed composite drainage and gas production device according to the determined working mode; wherein, the working channel of the auxiliary drainage mode is from the reagent injection system, through the gas-liquid separation and drainage system, to the blowdown ignition system; the working channel of the gas gathering station mode is from the reagent injection system to the gas gathering station; The switching working mode is based on the current working mode, observing the gas production of the target gas well, and switching between the auxiliary liquid drainage mode and the gas gathering station gas gathering mode through the valve control system according to the gas production situation; wherein, the switching working mode includes the following two situations: If the current working mode is the gas gathering mode of the gas gathering station, the gas gathering situation of the gas gathering station is used to determine whether the target gas well is in a continuous liquid-carrying production state; if so, the gas gathering mode of the gas gathering station is maintained; if not, the working channel of the gas gathering mode of the gas gathering station is closed through the valve control system, the working channel of the auxiliary drainage mode is opened, and a foaming object is injected into the target gas well through the reagent injection system; If the current working mode is the auxiliary drainage mode, switching the working mode includes the following steps: obtaining the pressure and gas production information of the corresponding fluid inside the high-pressure closed composite drainage and gas production device through the pressure measuring system and the flow detection device; adjusting the flow rate at the wellhead of the target gas well and the opening of the needle valve (17) and the ball valve (16) in the valve control system in a timely manner according to the pressure change; inferring whether the target gas well meets the conditions for continuous liquid production through the obtained pressure and gas production information; if so, closing the working channel of the auxiliary drainage mode through the valve control system and opening the working channel of the gas gathering mode of the gas gathering station; if not, maintaining the auxiliary drainage mode.

2. A method for producing gas at a gas wellhead by sealing, depressurizing, and draining water as claimed in claim 1, characterized in that: In the process of determining the working mode, if the target gas well meets the conditions for continuous liquid-carrying production, the gas gathering station gas gathering mode is selected; if the target gas well does not meet the conditions for continuous liquid-carrying production, the auxiliary liquid drainage mode is selected.

3. A method for producing gas by sealing, depressurizing and draining water at the wellhead of a gas well as claimed in claim 1, characterized in that: When the determined working mode is the auxiliary discharge mode, the startup process includes the following steps: Throwing foaming objects into the target gas well through the reagent injection system; The working channel of the auxiliary drainage mode is opened through the valve control system, so that the fluid in the target gas well enters the gas-liquid separation drainage system from the reagent injection system. During this period, the defoaming balance tank (4) in the reagent injection system is used to defoam the passing fluid; Use the gas-liquid separation and drainage system to separate the fluid into gas and liquid; The liquid obtained by gas-liquid separation is collected by using a liquid storage device in the gas-liquid separation and drainage system; The gas obtained from gas-liquid separation is burned using a blowdown ignition system.

4. A method for producing gas at a gas wellhead by sealing, depressurizing, and draining water as claimed in claim 3, characterized in that: The reagent injection system includes a rod thrower, a defoaming balance tank and a wellhead oil production tree; the blowout ignition system includes a first gate valve; the valve control system also includes a pressure-controlled regulating valve connected between the wellhead oil production tree and the defoaming balance tank, a first safety valve connected between the gas-liquid cyclone separator and the mist collector, and a second safety valve connected between the gas-liquid cyclone separator and the steam trap; then, the working channel for opening the auxiliary discharge mode includes opening the pressure-controlled regulating valve (3), the first safety valve (14), the second safety valve (15), the ball valve (16) and the needle valve (17) in the valve control system and the first gate valve (24) in the blowout ignition system.

5. A method for producing gas by depressurizing and draining water at a gas wellhead in a sealed manner as claimed in claim 3, characterized in that: The foaming object is a foaming rod and / or a foaming agent.

6. A method for producing gas by depressurizing and draining water at a gas wellhead in a sealed manner as claimed in claim 3, characterized in that: During the gas-liquid separation process, the gas-liquid cyclone separator (7) in the gas-liquid separation and drainage system is used to perform preliminary gas-liquid separation on the inflowing fluid, the mist collector (8) in the gas-liquid separation and drainage system is used to perform secondary gas-liquid fine separation on the gas phase of the gas-liquid cyclone separator (7), and the steam trap (9) in the gas-liquid separation and drainage system is used to buffer the liquid phases of the gas-liquid cyclone separator (7) and the mist collector (8).

7. A method for producing gas at a gas wellhead by sealing, depressurizing, and draining water as claimed in claim 1, characterized in that: The process of connecting the device also includes laying out a control circuit (29), and enabling the temperature measuring device (22), the pressure measuring system and the flow detection device to communicate with the computer console (23) through the control circuit (29).

8. A method for producing gas at a gas wellhead by sealing, depressurizing, and draining water as claimed in claim 7, characterized in that: During the switching of the working modes, if the current working mode is the auxiliary drainage mode, the pressure and gas production data of the corresponding fluid inside the high-pressure closed composite drainage and gas production device are remotely obtained through the computer console (23), and the obtained pressure data and gas production data are converted into coordinate curve graphs respectively using the computer console (23).

9. A method for producing gas by sealing, depressurizing and draining water at the wellhead of a gas well as claimed in claim 1, characterized in that: The drainage and gas production work also includes pressure test, adjustment and calibration, and the pressure test, adjustment and calibration includes the following steps: S1, sets the tripping threshold for the pressure-controlled regulating valve (3); S2, filling water into the high-pressure closed composite drainage and gas production device to make the internal pressure reach 0.8MPa; S3, observe whether the pressure-controlled regulating valve (3) trips; if so, take remedial measures for the pressure-controlled regulating valve (3), including repair, replacement, and resetting the trip threshold, and then return to step S2; if not, proceed to step S4; S4, wait for 10 minutes and observe whether there is any leakage in the high-pressure sealed composite drainage and gas production device; if there is, repair the leak and return to step S2; if not, go to step S5; S5, filling water into the high-pressure closed composite drainage and gas production device until the internal pressure reaches 3 MPa; S6, observe whether the pressure-controlled regulating valve (3) trips; if so, take remedial measures for the pressure-controlled regulating valve (3), including repair, replacement, and resetting the trip threshold, and then return to step S2; if not, proceed to step S7; S7, wait for 30 minutes and observe whether there is any leakage in the high-pressure sealed composite drainage and gas production device; if there is, repair the leak and return to step S2; if not, go to step S8; S8, filling water into the high-pressure closed composite drainage and gas production device until the internal pressure reaches 6 MPa; S9, observe whether the pressure-controlled regulating valve (3) trips; if so, take remedial measures for the pressure-controlled regulating valve (3), including repair, replacement, and resetting the trip threshold, and then return to step S2; if not, proceed to step S10; S10, wait for 30 minutes and observe whether the high-pressure sealed composite drainage and gas production device has any leakage; if yes, repair the leakage location and return to step S2; if not, the pressure test adjustment and calibration is completed.

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