Long-life-cycle gas well production pipe column and gas production method thereof

Abstract

The invention provides a long-life-cycle gas well production pipe column and a gas production method thereof. The long-life-cycle gas well production pipe column comprises a shaft, a double-pipe oil pipe hanger, a first oil pipe, a second oil pipe, a plurality of subsurface safety valves, a plurality of gas lift valves, a plurality of double-pipe packers, a plurality of production sliding sleeves and a plurality of seating connectors. The first oil pipe and the second oil pipe are hung in a shaft through the double-pipe oil pipe hanger, and the multiple double-pipe packers are used for packing the shaft and fixing the first oil pipe and the second oil pipe; the subsurface safety valves and the gas lift valves are installed on the first oil pipe and the second oil pipe, and the subsurface safety valves and the gas lift valves are all arranged on the upper side, close to the double-pipe oil pipe hanger, of the double-pipe packer. According to the method, long-life-cycle production of the gas well is achieved in the mode of'three-stage relay gas production 'in the initial stage, the middle stage and the later stage, the problem of wellbore liquid accumulation is effectively avoided, and reservoir damage can be reduced to the maximum extent while it is guaranteed that the yield target is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of gas well production in the petroleum industry, and particularly to a gas well production string with a long service life and a gas production method therefor. Background Art

[0002] Gas well production methods at home and abroad, whether on land or at sea, mainly rely on the natural flow method, and generally some liquids will be produced in gas wells. There are two sources of gas well liquids. One is that free water or hydrocarbon condensate in the formation seeps into the wellbore together with the gas, and the other is that natural gas containing water vapor in the formation flows into the wellbore, and condensate water appears due to heat loss. During the initial production period, the gas production volume of the gas well is large, and the liquid is carried to the ground by the gas in the form of liquid droplets, and the gas well maintains continuous production. However, as the production time of the gas well extends, the formation energy gradually decreases, and the gas well production volume decreases accordingly. When the gas production volume of the gas well is not sufficient to carry the liquid in the wellbore to the ground, the liquid will slip from the gas phase to the bottom of the well and form liquid accumulation at the bottom of the well. The liquid accumulation in the gas well leads to an increase in the bottom-hole backpressure, and at the same time causes the water lock effect in the near-wellbore zone, reducing the gas-phase permeability, which will further reduce the gas well production volume and increase the liquid accumulation amount at the bottom of the well. If not discovered and measures taken in time, it will cause a rapid decline in gas production, and in severe cases, lead to the blowout stop of the gas well. Liquid accumulation in gas wells has become one of the most important problems restricting the high-quality development of gas fields.

[0003] To address the problem of liquid accumulation in gas wells, a drainage gas production process is often used to restore gas well production. Commonly used drainage gas production processes include various processes such as gas lift, electric pump, and rapid production string. Different process technologies have their own technical characteristics and application conditions, but the above-mentioned drainage production processes need to carry out corresponding workover operations and change the gas well lifting method in combination with reservoir characteristics, production characteristics, process costs, etc. Carrying out workover operations and changing the gas well lifting method not only increases the operation cost and affects the overall economic benefits of the gas field, but also increases the soaking time of the bottom-hole liquid accumulation in the gas well and expands the near-wellbore pollution zone of the gas well. Even if the gas well production can be restored in time, it will cause irreversible damage to the gas well productivity.

[0004] If the gas well production plan can be well prepared at the initial stage of gas well production, predict the liquid accumulation time of the gas well in advance, convert the production method without moving the production string, avoid or reduce the degree of bottom-hole liquid accumulation, and extend the maintenance-free period of the gas well to the greatest extent, the above two problems can be completely avoided, realizing the safe and efficient production of the gas well with a long service life without moving the production string, and providing guarantee for the sustainable development of the gas field. Therefore, it is necessary to design a gas well production string with a long service life and a gas production method therefor to meet the needs of long-term safe and efficient production of gas wells. Summary of the Invention

[0005] In view of the above-mentioned disadvantages of the prior art, the purpose of the present invention is to provide a gas well production string with a long service life and a gas production method therefor to solve the problems existing in the prior art.

[0006] To achieve the above and other related purposes, the present invention provides a production string for a long-life gas well, which includes a wellbore, a dual-tubing hanger, a first tubing, a second tubing, a plurality of downhole safety valves, a plurality of gas lift valves, a plurality of dual-tubing packers, a plurality of production sleeves, and a plurality of setting joints. The first tubing and the second tubing are suspended in the wellbore through the dual-tubing hanger, and a plurality of dual-tubing packers seal the wellbore and fix the first tubing and the second tubing; a plurality of the downhole safety valves and gas lift valves are installed on the first tubing and the second tubing, and a plurality of the downhole safety valves and gas lift valves are arranged on the upper side of the dual-tubing packer close to the dual-tubing hanger; a plurality of the setting joints are installed at the ends of the first tubing and the second tubing away from the dual-tubing hanger, and the setting joints are arranged on the lower side of the dual-tubing packer away from the dual-tubing hanger; a plurality of the production sleeves are installed on the outer circumferential surfaces of the first tubing and the second tubing, and the production sleeves are arranged between two adjacent dual-tubing packers.

[0007] Preferably, the dual-tubing packer includes a top dual-tubing packer and a bottom dual-tubing packer. A plurality of the downhole safety valves and gas lift valves are arranged on the upper side of the top dual-tubing packer, and the downhole safety valves and gas lift valves are respectively installed on the first tubing and the second tubing; the setting joints are arranged on the lower side of the bottom dual-tubing packer, and the setting joints are respectively installed on the first tubing and the second tubing; the production sleeves are arranged between the top dual-tubing packer and the bottom dual-tubing packer, and the production sleeves are respectively installed on the outer circumferential surfaces of the first tubing and the second tubing; the production sleeves and the setting joints both achieve the plugging of the first tubing and the second tubing through wireline operations.

[0008] Preferably, both the first tubing and the second tubing are formed by butt-jointing multiple tubing sections, and both ends of the downhole safety valve, both ends of the gas lift valve, and both ends of the production sleeve are threadedly connected to the tubing sections.

[0009] Preferably, the diameters of the first tubing and the second tubing can be the same or different.

[0010] Preferably, the well deviation angle at the production sleeve and the setting joint does not exceed 55°.

[0011] To achieve the above or other purposes, the present invention also discloses a gas production method for a production string of a long-life gas well, which uses the above production string of a long-life gas well, and the steps are as follows:

[0012] S1: Design the production string of the gas well; determine the size specifications of the first tubing and the second tubing according to the gas production index of the gas well, and design the model and installation depth of the gas lift valve according to the gas production index of the gas well; calculate the conversion time of each stage and the production form of each stage based on the minimum critical gas-carrying capacity formula of the gas well and the reservoir production allocation;

[0013] S2: Suspend the first tubing string and the second tubing string designed in step S1 in the wellbore through a dual-tubing hanger; use several dual-packers to seal the wellbore and fix the first tubing string and the second tubing string; install several downhole safety valves, several gas lift valves, several production sleeves, and several landing nipples at corresponding positions on the first tubing string and the second tubing string respectively.

[0014] S3: In the initial stage of gas well production; open the downhole safety valves on the first tubing string and the second tubing string for blowout induction and production. In the initial stage of production, the formation energy is sufficient, and the first tubing string and the second tubing string carry out gas production by natural flow simultaneously.

[0015] S4: In the middle stage of gas well production; based on the initial time of the gas well calculated in step S1, when the first tubing string and the second tubing string carry out gas production by natural flow simultaneously in step S3 reaches the designed time, the formation energy decreases and the production rate gradually decreases. Convert the production method from the way of the first tubing string and the second tubing string carrying out gas production by natural flow simultaneously to single-tubing natural flow gas production, or dual-tubing gas lift gas production, or a combination of the above two gas production methods until the end of the middle stage of gas production.

[0016] S5: In the late stage of gas well production; based on the middle time of the gas well calculated in step S1, when the single-tubing natural flow gas production, or dual-tubing gas lift gas production, or a combination of the above two gas production methods in step S4 reaches the designed time, the formation energy further decreases. Convert the production method from the single-tubing natural flow gas production, or dual-tubing gas lift gas production, or a combination of the above two gas production methods to single-tubing gas lift gas production until the end of the late stage of gas production.

[0017] Preferably, when using the combination of the above two gas production methods in step S4, the dual-tubing gas lift method can be adopted first, and then the single-tubing natural flow gas production method; or the single-tubing natural flow gas production method can be adopted first, and then the dual-tubing gas lift method.

[0018] Preferably, the diameters of the first tubing string and the second tubing string in step S1 can be the same or different; when the diameters of the first tubing string and the second tubing string are different, in the middle stage of gas production in step S4, when adopting the single-tubing natural flow gas production method, the tubing string with a larger diameter can be used for natural flow first, and then the tubing string with a smaller diameter.

[0019] Preferably, in step S4 and step S5, when the productivity of a certain production layer in the reservoir is low or the water production is serious, the production sleeve or the landing nipple of the corresponding production layer can be closed through wireline operation to reduce the risk of liquid accumulation.

[0020] As described above, the gas production method of the production string for long-life gas wells of the present invention has the following beneficial effects:

[0021] 1. The present invention can ensure production volume and reduce damage to the gas field reservoir. By adopting the "three-stage relay gas production" method in the initial, middle, and late stages, long-life production of gas wells is achieved, effectively avoiding the problem of liquid accumulation in the wellbore. While ensuring the achievement of production volume targets, it can also minimize reservoir damage to the greatest extent.

[0022] 2. The present invention is easy to operate and convenient for on-site management. The conversion of the production method in the present invention is completed on the ground, which is convenient and fast to operate. The production volume of each tubing is adjusted through the surface choke, facilitating the allocation of layered production volume.

[0023] 3. The present invention reduces operations and saves workover costs. Compared with the conventional single-tubing string, the present invention reduces the frequency of workover operations and saves operation costs, which is particularly obvious for offshore gas wells.

[0024] 4. In the present invention, layer adjustment is flexible and suitable for different production requirements. The present invention can achieve dual-tubing layered control. For layer adjustment needs, production sleeves and setting joints are reserved on the first tubing and the second tubing. When layer adjustment is required, the production sleeve is switched or the setting joint is set through wireline operation. The number of production layers is not limited. At the same time, a dual-tubing Christmas tree is configured on the ground, and wireline operation on the dual tubing can be implemented separately.

[0025] 5. The present invention is flexibly designed to meet different production allocation requirements: The sizes of the first tubing and the second tubing can be flexibly designed according to the production allocation requirements of the reservoir. The minimum critical liquid-carrying gas volume in each production stage is calculated according to the critical liquid-carrying flow formula of the gas well, and the sizes of the dual tubing are designed and selected (which can be tubings with different sizes or tubings of the same size, etc.). At the same time, the parameters of the gas lift valve (the number of gas lift valve stages and the setting depth) are optimized to ensure continuous production of the gas well in each stage without liquid accumulation in the wellbore.

[0026] 6. The present invention is applicable to a wide range of well types. The present invention is applicable to vertical wells, directional wells, and horizontal wells. Due to wireline operation for layer adjustment, the maximum well deviation angle at the production sleeve and the setting joint does not exceed 55°, and most gas well types can be applicable. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic structural diagram of the production string for a long-life gas well of the present invention.

[0028] DESCRIPTION OF THE REFERENCE NUMERALS:

[0029] 1. Dual-tubing hanger; 2. Downhole safety valve; 3. First tubing; 4. Second tubing; 5. Gas lift valve; 6. Top dual-tubing packer; 7. Production sleeve; 8. Bottom dual-tubing packer; 9. Setting joint; 10. Wellbore. DETAILED DESCRIPTION OF THE INVENTION

[0030] The following specific embodiments illustrate the implementation manners of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification.

[0031] It should be noted that the structures, ratios, sizes, etc. shown in the drawings of this specification are only used to cooperate with the content disclosed in the specification for those skilled in the art to understand and read, and are not used to limit the limiting conditions for the implementation of the present invention. Therefore, they do not have substantial technical significance. Any modification of the structure, change of the proportional relationship, or adjustment of the size, without affecting the effects that the present invention can produce and the purposes that can be achieved, should still fall within the scope covered by the technical content disclosed in the present invention. At the same time, the terms such as "upper", "lower", "left", "right", "middle", and "one" cited in this specification are only for the convenience of clear description and are not used to limit the scope for the implementation of the present invention. The change or adjustment of their relative relationships, without substantial change in the technical content, should also be regarded as the scope for the implementation of the present invention.

[0032] As Figure 1 shown, the present invention provides a production string for a long-life gas well, which includes a wellbore 10, a dual-tubing hanger 1, a first tubing 3, a second tubing 4, a plurality of downhole safety valves 2, a plurality of gas lift valves 5, a plurality of dual-tubing packers, a plurality of production sleeves 7, and a plurality of landing joints 9. The first tubing 3 and the second tubing 4 are suspended in the wellbore 10 through the dual-tubing hanger 1. The plurality of dual-tubing packers seal off the wellbore 10 and fix the first tubing 3 and the second tubing 4; the plurality of downhole safety valves 2 and gas lift valves 5 are installed on the first tubing 3 and the second tubing 4, and the plurality of downhole safety valves 2 and gas lift valves 5 are all arranged on the upper side of the dual-tubing packer close to the dual-tubing hanger 1; the plurality of landing joints 9 are installed at the ends of the first tubing 3 and the second tubing 4 away from the dual-tubing hanger 1, and the landing joints 9 are arranged on the lower side of the dual-tubing packer away from the dual-tubing hanger 1; the plurality of production sleeves 7 are installed on the outer circumferential surfaces of the first tubing 3 and the second tubing 4, and the production sleeves 7 are arranged in the middle of two adjacent dual-tubing packers.

[0033] The production string for a long-life gas well involved in the present invention is provided with a first tubing 3 and a second tubing 4 at the same time, and can flexibly adjust the gas production methods in different stages according to the initial, middle, and late stages of gas field development, can meet different production allocation requirements, ensure the continuous production of gas wells in each stage, and prevent liquid accumulation in the wellbore 10. The production sleeves 7 and landing joints 9 are provided in the present invention. By operating the production sleeves 7 and landing joints 9 with wireline operations, the number of production layers in the gas field can be reasonably adjusted, the number of production layers is not limited, and different production requirements can be met.

[0034] Preferably, as Figure 1As shown in the figure, the dual-tubing packer includes a top dual-tubing packer 6 and a bottom dual-tubing packer 8. A number of downhole safety valves 2 and gas lift valves 5 are arranged above the top dual-tubing packer 6, and the downhole safety valves 2 and gas lift valves 5 are respectively installed on the first tubing 3 and the second tubing 4; the landing nipple 9 is arranged below the bottom dual-tubing packer 8, and the landing nipple 9 is respectively installed on the first tubing 3 and the second tubing 4; the production sliding sleeve 7 is arranged between the top dual-tubing packer 6 and the bottom dual-tubing packer 8, and the production sliding sleeve 7 is respectively installed on the outer circumferential surfaces of the first tubing 3 and the second tubing 4; the production sliding sleeve 7 and the landing nipple 9 both achieve the plugging of the first tubing 3 and the second tubing 4 through wireline operations.

[0035] Preferably, both the first tubing 3 and the second tubing 4 are formed by butt-jointing multiple tubing sections, and both ends of the downhole safety valve 2, both ends of the gas lift valve 5, and both ends of the production sliding sleeve 7 are threadedly connected to the tubing sections separately.

[0036] In this embodiment, the number of downhole safety valves 2 is two, which are respectively installed on the first tubing 3 and the second tubing 4. The number of gas lift valves 5 is several, which are arranged on the first tubing 3 and the second tubing 4 in the vertical direction. The number of landing nipples 9 is two, which are respectively arranged at the bottom ends of the first tubing 3 and the second tubing 4.

[0037] Furthermore, in this embodiment, the number of dual-tubing packers is two, namely the top dual-tubing packer 6 and the bottom dual-tubing packer 8. The production sliding sleeve 7 is located between the top dual-tubing packer 6 and the bottom dual-tubing packer 8, and is used to control whether the inside of the first tubing 3 and the second tubing 4 is connected to the production layer. Therefore, in other embodiments, the number of dual-tubing packers can also be multiple, dividing the wellbore 10 into multiple production layers, and a production sliding sleeve 7 is arranged between each production layer, so as to realize flexible adjustment of different production layers. The production sliding sleeve 7 closes or connects the channel between the first tubing 3, the second tubing 4 and the wellbore 10 space by moving the inner sleeve; when the hole of the inner sleeve faces the channel of the production sliding sleeve 7 body, the production sliding sleeve 7 is in the open state; when the two are staggered, the production sliding sleeve 7 is in the closed state.

[0038] Preferably, in this embodiment, the diameters of the first tubing 3 and the second tubing 4 can be the same or different.

[0039] Preferably, in this embodiment, the well deviation angle at the production sliding sleeve 7 and the landing nipple 9 does not exceed 55°.

[0040] Furthermore, in this embodiment, a parallel dual-tubing Christmas tree is also provided at the top of the first tubing 3 and the second tubing 4.

[0041] To achieve the above or other purposes, the present invention also discloses a gas production method for a gas well production string with a long service life. Using the above-mentioned gas well production string with a long service life, the steps are as follows:

[0042] A1: Design the gas well production string; determine the length specifications and diameter specifications of the first tubing 3 and the second tubing 4 according to the gas well production allocation index, and design the model and installation depth of the gas lift valve 5 according to the gas well production allocation index; calculate the conversion time of each stage and the production form of each stage based on the minimum critical gas-carrying capacity formula of the gas well and the reservoir production allocation.

[0043] A2: Hang the first tubing 3 and the second tubing 4 designed in step A1 in the wellbore 10 through the dual tubing hanger 1; use the top dual-packer 6 and the bottom dual-packer 8 to seal off the wellbore 10 respectively to fix the first tubing 3 and the second tubing 4; install two downhole safety valves 2 on the first tubing 3 and the second tubing 4 respectively; install a number of gas lift valves 5 on the first tubing 3 and the second tubing 4 respectively; install a number of production sleeves 7 on the outer peripheral surfaces of the first tubing 3 and the second tubing 4 between the top dual-packer 6 and the bottom dual-packer 8; install two landing joints 9 at the bottom end faces of the first tubing 3 and the second tubing 4 respectively.

[0044] A3: In the initial stage of gas well production; open the downhole safety valves 2 on the first tubing 3 and the second tubing 4 for blowout production. In the initial stage of production, the formation energy is sufficient, and the first tubing 3 and the second tubing 4 carry out gas production by natural flow simultaneously; at this time, the gas production method is dual-tubing natural flow until the end of the initial production stage; the dual-tubing natural flow method can increase the flow channel, minimize the flow resistance, reduce the frictional loss on the inner wall of the wellbore 10, and achieve efficient production in the initial stage.

[0045] A4: In the middle stage of gas well production; based on the initial time of the gas well calculated in step A1, when the simultaneous gas production mode of the first tubing 3 and the second tubing 4 in step A3 reaches the designed time, the formation energy decreases and the production gradually decreases. Convert the production mode from the simultaneous natural flow gas production of the first tubing 3 and the second tubing 4 to single-tubing natural flow gas production, or dual-tubing gas lift gas production, or a combination of the above two gas production methods until the end of the middle stage of gas production; in the middle stage of gas production, stable liquid carrying is achieved, avoiding liquid accumulation in the wellbore 10 and ensuring continuous and stable production in the middle stage.

[0046] A5: The late stage of gas production from a gas well; based on the mid-term time of the gas well calculated in step A1, when the single-tubing natural flow gas production, or the double-tubing gas lift gas production, or the combination of the above two gas production methods in step A4 reaches the designed time, the formation energy further decreases. The production method is converted from the single-tubing natural flow gas production, or the double-tubing gas lift gas production, or the combination of the above two gas production methods to the single-tubing gas lift gas production method until the end of the late stage of gas production. In the late stage of gas production, the continuous production time of the gas well is maximally extended without pulling the tubing string, while reducing the frequency of tubing string operation, decreasing the workover cost per well, achieving the purpose of stable production of the gas well with a long life cycle, and enhancing the final economic benefit per well.

[0047] Preferably, when the above two gas production combination methods are used in step A4, the double-tubing gas lift method can be adopted first, and then the single-tubing natural flow gas production method; or the single-tubing natural flow gas production method can be adopted first, and then the double-tubing gas lift method. In this embodiment, the double-tubing gas lift method is that both the first tubing 3 and the second tubing 4 are connected, and gas is injected into the wellbore 10 through a gas pump. The gas enters the first tubing 3 and the second tubing 4 through the gas lift valve 5, and continuous gas production of the gas well is realized according to the principle of fluid mechanics. The single-tubing natural flow method is that the first tubing 3 or the second tubing 4 is connected.

[0048] Preferably, the diameters of the first tubing 3 and the second tubing 4 in step A1 can be the same or different; when the diameters of the first tubing 3 and the second tubing 4 are different, in the mid-term stage of gas production in step A4, the single-tubing natural flow gas production method can first use the tubing with a larger diameter for natural flow, and then use the tubing with a smaller diameter for natural flow. Further, in other embodiments, in the mid-term stage of gas production, the well can also use the tubing with a larger diameter for natural flow first, then the tubing with a smaller diameter for natural flow, and then the tubing with a larger diameter for gas lift. In the late stage of gas production, the tubing with a smaller diameter can be used for gas lift; of course, there are other gas production methods, which are not elaborated here in this embodiment. The adjustment of the gas production method in the present invention is more flexible and there are more options.

[0049] Preferably, in steps A4 and A5, when the productivity of a certain producing formation in the reservoir is low or the water production is serious, the production sliding sleeve 7 or the setting joint 9 of the corresponding producing formation can be closed through wireline operation to reduce the risk of liquid accumulation. In this embodiment, the number of double-tubing packers can be multiple, and the number of production sliding sleeves 7 can be multiple, so that the reservoir can be divided into several producing formations. When the production of a certain producing formation is insufficient or there is too much accumulated water and it is not suitable for gas production, the production sliding sleeve 7 of this producing formation can be closed through wireline operation, thereby flexibly adjusting the producing formation.

[0050] The gas production method of the long-life cycle gas well production tubing string involved in the present invention has the following beneficial effects:

[0051] 1. The present invention realizes the long-life production of gas wells through the "three-stage relay gas production" method, effectively avoiding the problem of liquid accumulation in wellbore 10. While ensuring the achievement of production targets, it minimizes reservoir damage to the greatest extent.

[0052] 2. In the present invention, the conversion of the production methods in the initial, middle, and late stages is completed on the ground. The operation is convenient and fast, and the production of each tubing can be adjusted through the surface choke, facilitating the allocation of stratified production.

[0053] 3. Compared with the conventional single-tubing string, the present invention reduces the frequency of workover operations and saves the cost of workover operations, which is particularly obvious for offshore gas wells.

[0054] 4. In the present invention, layer adjustment is flexible and suitable for different production requirements. The present invention can achieve dual-tubing stratified control. For layer adjustment needs, production sleeves 7 and setting joints 9 are reserved on the first tubing 3 and the second tubing 4. Stratified control of production layers can be achieved through wireline operations on each tubing. At the same time, the number of layers that can be stratified mined is not limited, realizing fine stratified control. For example, according to the results of productivity profile testing, if the productivity of a certain production layer is low or the water production is serious, the production channel can be closed in time through wireline operations to reduce the risk of liquid accumulation, achieve balanced production of each layer, and achieve the purpose of production optimization.

[0055] 5. The maximum well deviation angle at the production sleeve 7 and the setting joint 9 of the present invention does not exceed 55°, and most gas well types can be used, such as vertical wells, directional wells, and horizontal wells, etc., with a wide range of applications.

[0056] 6. In the present invention, the production plan of the gas well is made at the initial stage of gas well production, the liquid accumulation time of the gas well is predicted in advance, and the production method is converted without moving the tubing string, avoiding or reducing the degree of bottom-hole liquid accumulation, and extending the workover-free period of the gas well to the greatest extent. The above two problems can be completely avoided, realizing the safe and efficient production of gas wells with a long-life cycle without moving the tubing string, providing a guarantee for the sustainable development of gas fields.

[0057] Therefore, the present invention effectively overcomes various disadvantages in the prior art and has high industrial utilization value.

[0058] The above embodiments are only illustrative of the principles and effects of the present invention, and are not used to limit the present invention. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes completed by those with ordinary knowledge in the technical field without departing from the spirit and technical ideas disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. A production string for a long-life gas well, characterized in that: It includes a wellbore (10), a dual - tubing hanger (1), a first tubing string (3), a second tubing string (4), several downhole safety valves (2), several gas lift valves (5), several dual - tubing packers, several production sleeves (7), and several landing joints (9). The first tubing string (3) and the second tubing string (4) are suspended in the wellbore (10) through the dual - tubing hanger (1). Several dual - tubing packers isolate the wellbore (10) and fix the first tubing string (3) and the second tubing string (4). Several of the downhole safety valves (2) and gas lift valves (5) are installed on the first tubing string (3) and the second tubing string (4), and several of the downhole safety valves (2) and gas lift valves (5) are both arranged above the dual - tubing packer close to the dual - tubing hanger (1). Several of the landing joints (9) are installed at the ends of the first tubing string (3) and the second tubing string (4) away from the dual - tubing hanger (1), and the landing joints (9) are arranged below the dual - tubing packer away from the dual - tubing hanger (1). Several of the production sleeves (7) are installed on the outer circumferential surfaces of the first tubing string (3) and the second tubing string (4), and the production sleeves (7) are arranged between adjacent dual - tubing packers.

2. The long-life gas well production string according to claim 1, wherein: The dual - tubing packer includes a top dual - tubing packer (6) and a bottom dual - tubing packer (8). Several of the downhole safety valves (2) and gas lift valves (5) are both arranged above the top dual - tubing packer (6), and the downhole safety valves (2) and gas lift valves (5) are respectively installed on the first tubing string (3) and the second tubing string (4). The landing joint (9) is arranged below the bottom dual - tubing packer (8), and the landing joint (9) is respectively installed on the first tubing string (3) and the second tubing string (4). The production sleeve (7) is arranged between the top dual - tubing packer (6) and the bottom dual - tubing packer (8), and the production sleeve (7) is respectively installed on the outer circumferential surfaces of the first tubing string (3) and the second tubing string (4). The production sleeve (7) and the landing joint (9) both achieve the plugging of the first tubing string (3) and the second tubing string (4) through wireline operations.

3. The production string for a long-life gas well according to claim 1, wherein: Both the first tubing string (3) and the second tubing string (4) are formed by butt - joining multiple tubing sections. Both ends of the downhole safety valve (2), both ends of the gas lift valve (5), and both ends of the production sleeve (7) are thread - connected to the tubing sections.

4. The long-life gas well production string according to claim 1, characterized in that: The diameters of the first tubing string (3) and the second tubing string (4) can be the same or different.

5. The production string for a long-life gas well according to claim 1, characterized in that: The well deviation angle at the production sleeve (7) and the landing joint (9) does not exceed 55°.

6. A gas production method for a gas well production string with a long service life, using the gas well production string with a long service life described in any one of claims 1-5, characterized in that: The steps are as follows: S1: Design the gas well production string; determine the size specifications of the first tubing string (3) and the second tubing string (4) according to the gas well production allocation index, design the model and installation depth of the gas lift valve (5) according to the gas well production allocation index; calculate the conversion time of each stage and the exploitation form of each stage based on the minimum critical gas - carrying capacity formula of the gas well and the reservoir production allocation. S2: Suspend the first tubing string (3) and the second tubing string (4) designed in step S1 in the wellbore (10) through a dual-tubing hanger (1); use a number of dual-packers to isolate the wellbore (10) and fix the first tubing string (3) and the second tubing string (4); install a number of downhole safety valves (2), a number of gas lift valves (5), a number of production sleeves (7), and a number of landing joints (9) at corresponding positions on the first tubing string (3) and the second tubing string (4). S3: In the initial stage of gas well production; open the downhole safety valves (2) on the first tubing string (3) and the second tubing string (4) for blowout production. In the initial stage of production, the formation energy is sufficient, and the first tubing string (3) and the second tubing string (4) carry out gas production by natural flow simultaneously. S4: In the middle stage of gas well production; based on the initial time of the gas well calculated in step S1, when the first tubing string (3) and the second tubing string (4) produce gas simultaneously in step S3 reaches the designed time, the formation energy drops and the production rate gradually decreases. Convert the production mode from the first tubing string (3) and the second tubing string (4) producing gas by natural flow simultaneously to single-tubing natural flow gas production, or dual-tubing gas lift gas production, or a combination of the above two gas production methods until the end of the middle stage of gas production. S5: In the late stage of gas well production; based on the middle time of the gas well calculated in step S1, when the single-tubing natural flow gas production, or dual-tubing gas lift gas production, or a combination of the above two gas production methods in step S4 reaches the designed time, the formation energy further drops. Convert the production mode from the single-tubing natural flow gas production, or dual-tubing gas lift gas production, or a combination of the above two gas production methods to single-tubing gas lift gas production until the end of the late stage of gas production.

7. The gas production method of the gas production string for long-life gas wells according to claim 6, characterized in that: When using the combination of the above two gas production methods in step S4, the dual-tubing gas lift method can be used first, and then the single-tubing natural flow gas production method; or the single-tubing natural flow gas production method can be used first, and then the dual-tubing gas lift method.

8. The gas production method of the gas production string for long-life gas wells according to claim 7, characterized in that: The diameters of the first tubing string (3) and the second tubing string (4) in step S1 can be the same or different; when the diameters of the first tubing string (3) and the second tubing string (4) are different, in the middle stage of gas production in step S4, when using the single-tubing natural flow gas production method, the tubing string with a larger diameter can be used for natural flow first, and then the tubing string with a smaller diameter.

9. The gas production method of the gas production string for a long-life gas well according to claim 6, characterized in that: In steps S4 and S5, when the productivity of a certain producing formation in the reservoir is low or the water production is severe, the production sleeve (7) or the landing joint (9) of the corresponding formation can be closed by wireline operation to reduce the risk of liquid accumulation.

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