Compressed air energy storage straight inclined shaft high-frequency injection-production pipe column and well completion method

Abstract

The invention relates to a compressed air energy storage straight inclined shaft high-frequency injection and production string and a well completion method.The injection and production string is sequentially connected with an underground combined sealing device, an underground annulus flow limiting device and an underground safety valve through oil pipes from bottom to top, and the underground combined sealing device is formed by connecting a preset working barrel and a sealing working barrel in an inserted mode; a sealing insertion barrel seals a sealing insertion barrel sealing cavity of the preset lower outer barrel, a sealing assembly seals a sealing piece sealing cavity of the preset lower outer barrel, and the underground annulus flow limiting device is provided with a leather cup and a center pipe. And the flow limiting plates of the staggered converging flow channels are fixed in the flow limiting plate mounting grooves in the pipe wall of the central pipe, and a seat sealing hole and a seat sealing boosting hole are formed in the pipe wall without the flow limiting plate mounting grooves. The injection-production tubular column provided by the invention has a reverse well flushing function, scales and deposited wax in an oil pipe are cleaned through reverse circulation of well flushing fluid with a cleaning function, maintenance without moving the tubular column is realized, the conventional operation cost and time are reduced, and the working efficiency of a gas storage is improved.

Description

Technical Field

[0001] The present invention relates to the field of gas storage construction and carbon dioxide injection technology in oilfield development in the petroleum industry, and specifically to a high-frequency injection-production string and completion method for a compressed air energy storage vertical-inclined well. Background Art

[0002] Compared with traditional ground storage facilities, underground gas storage has the characteristics of large storage capacity, strong mobility, wide peak shaving range, long service life and high safety factor. The gas storage reservoirs built in the world today are mainly divided into four types according to the characteristics of underground gas storage layers, namely depleted oil and gas reservoir gas storage, aquifer gas storage, salt cavern gas storage, and abandoned mine gas storage. The stored gas is mainly natural gas, and its function is basically the same as that of a natural gas storage reservoir, both of which play the role of temporarily storing energy and regulating supply and demand during peak hours. However, due to different stored energies, the injection-production capabilities required for the injection-production wells in the two are quite different.

[0003] For natural gas storage reservoirs, since the supply and demand peaks of the stored natural gas are usually in the cold winter and spring seasons, injection is mainly carried out for injection-production wells in the hot summer and autumn seasons, and production is mainly carried out in the winter and spring seasons. The injection-production string works in one working state for a long period of time, and the stress alternating frequency is relatively low. Therefore, the working requirements for the packers in the string are relatively low. Conventional airtight packers can meet its working needs. For example, the following patented technologies: "Injection-production string and completion method using the same" disclosed in the authorized announcement number CN112647857B and "A completion string for an injection-production well in an oil and gas reservoir type gas storage" disclosed in the authorized announcement number CN206205797U both use packers for anchoring and sealing.

[0004] At the same time, since the natural gas in the reservoir of the natural gas storage reservoir does not require secondary energy conversion, and both injection and production are natural gas, the requirements for the gas displacement, flow rate, etc. in the injection-production string are also relatively low.

[0005] The energy stored in an air energy storage type gas storage reservoir is electric energy. The peak period of electric energy use is during the day, and the low period is at night. Therefore, it performs one access and storage per day to play the peak shaving function, and the injection-production frequency is relatively high. At the same time, the existing air in the gas storage reservoir is only a transmission medium during the energy conversion and storage process. The air energy storage type gas storage reservoir requires a turbine for secondary energy conversion. Therefore, it has high requirements for the gas purity, flow rate and displacement in the injection-production string.

[0006] The gas storage reservoirs with air storage built in China now are all of the salt cavern type. The underground reservoir is relatively clean and does not produce formation sand, so there is no need to consider the problem of formation sand production, and only the problems of scaling and corrosion of the injection-production string need to be considered.

[0007] If a compressed air energy storage cavern is established in a depleted oil and gas reservoir, the reservoir contains not only air, water vapor, etc., but also sand is more likely to be produced from the formation. If the injection-production string used in a salt cavern energy storage cavern is adopted for production, the problem of sand control in the injection-production wells in the cavern cannot be solved.

[0008] If the injection-production well string in a depleted oil and gas reservoir for storing natural gas conventionally is adopted in a compressed air energy storage cavern, the actual demand for the long-life operation of the injection-production wells in the cavern under the condition of high-frequency stress alternation cannot be met, as described in articles such as "Research on the Dynamic Characteristics of Fluid-Induced Vibration and Buckling of Injection-Production Strings in Energy Storage Caverns" and "Buckling Behavior of Oil Tubes in Energy Storage Caverns under Multi-Cycle Injection-Production Conditions".

[0009] Therefore, a new type of injection-production string is urgently needed to solve the above problems. Summary of the Invention

[0010] To solve the above existing problems, the present invention provides a high-frequency injection-production string and a well completion method for a vertical-inclined well of compressed air energy storage, mainly solving the problem that the injection-production strings used in existing salt cavern and depleted energy storage caverns cannot meet the use requirements of the injection-production string in a compressed air energy storage cavern established in a depleted oil reservoir, and providing an injection-production string applicable to a compressed air energy storage cavern with a high injection-production frequency. The production efficiency of the compressed air energy storage cavern is improved, and the injection-production benefit is increased.

[0011] The technical solution of the present invention is: a vertical and inclined well high-frequency injection and production string for compressed air energy storage, which is provided with a tubing string and a downhole safety valve. Among them: the injection and production string is successively connected with a downhole combined sealing device, a downhole annulus flow-limiting device and a downhole safety valve from bottom to top through the tubing string. The downhole combined sealing device is formed by inserting a preset working barrel and a sealing working barrel; in the preset working barrel, a preset locking ring with a buttress thread is installed between a preset upper outer barrel and a preset lower outer barrel. The preset upper outer barrel is connected to the preset lower outer barrel, and the preset working barrel is pre-lowered into a preset position in the well together with the completion string; the sealing working barrel includes a sealing component mainly composed of a sealing insertion barrel and a sealing assembly and an inner barrel; the inner barrel is provided with a backwashing hole and a backwashing control hole, and the outer circle of the limiting step three in the inner barrel is processed with a buttress thread; the sealing working barrel is connected to the lower end of the injection and production string and lowered into the preset working barrel. The inner barrel is connected to the buttress thread in the preset locking ring. The sealing insertion barrel seals the sealing insertion barrel sealing cavity of the preset lower outer barrel, and the sealing assembly seals the sealing element sealing cavity of the preset lower outer barrel; the downhole annulus flow-limiting device is provided with a cup leather and a central pipe. A flow-limiting plate with an alternating converging flow channel is fixed in a flow-limiting plate installation groove in the pipe wall of the central pipe, and a setting hole and a setting boosting hole are arranged in the pipe wall without a flow-limiting plate installation groove; above the upper pushing barrel limiting step of the central pipe, a flow-limiting device sliding barrel, a cup leather and an upper pushing barrel are successively installed from top to bottom; a flow-limiting device limiting ring with a locking ring installed is installed in the flow-limiting device sliding barrel above the cup leather, and the locking ring is installed in a locking ring groove on the outer circle of the central pipe; the upper pushing barrel is in buttress thread fit with a flow-limiting device locking ring installed in a locking ring installation groove of the central pipe.

[0012] Preferably, the sealing working barrel is further provided with an upper locking ring, a working barrel sliding barrel, a working barrel spring, a disc spring, a middle locking ring and a sealing pressing ring. The upper locking ring, the working barrel sliding barrel and the working barrel spring are successively installed above the limiting step three from top to bottom; the disc spring, the sealing insertion barrel, the middle locking ring, the sealing assembly and the sealing pressing ring are successively installed below the limiting step three from top to bottom.

[0013] Preferably, the top of the ring body of the preset locking ring is provided with a locking ring torque transmission spline, the lower inner circle of the preset locking ring is provided with a buttress thread, and the preset locking ring is an open ring axially provided with a straight or inclined through groove; the preset upper outer barrel is a non-uniform diameter cylindrical body. The upper inner cavity of the preset upper outer barrel is provided with an internal thread for connecting with the completion string, the lower part is a threaded inner cavity, and the middle inner cavity is provided with a locking ring limiting step and an upper outer barrel torque transmission spline is arranged on the inner circle of the locking ring limiting step; the upper outer barrel torque transmission spline can cooperate with the locking ring torque transmission spline at the top of the ring body of the preset locking ring, and after cooperation, the preset locking ring is exactly located in the locking ring installation cavity between the locking ring limiting step and the lower threaded inner cavity.

[0014] Preferably, the preset lower outer cylinder is a non-uniform-diameter cylinder. External threads are provided on the outer circles at both ends of the preset lower outer cylinder, and can be respectively threadedly connected to the internal threads in the threaded inner cavity at the lower part of the preset upper outer cylinder and the lower casing in the completion string; the upper inner cavity of the preset lower outer cylinder is a sealed insertion cylinder sealing cavity, and the lower inner cavity is a seal sealing cavity; the sealed insertion cylinder sealing cavity is a conical cavity.

[0015] Preferably, the sealed insertion cylinder can be made of rubber or polymer materials, soft metal or shape memory alloy. The lower outer circle of the sealed insertion cylinder is a conical outer circle, which cooperates with the sealed insertion cylinder sealing cavity of the preset lower outer cylinder; a disc spring top ring is also installed between the disc spring and the sealed insertion cylinder.

[0016] Preferably, the inner cylinder is a non-uniform-diameter cylinder. Injection-production string connection threads and spare part connection threads are respectively arranged at the upper and lower ends of the inner cylinder; limiting steps one, two, three, four, and five are successively arranged on the outer circle of the inner cylinder from top to bottom. The outer circles of the limiting steps one, two, three, four, and five are all precision-machined outer surfaces.

[0017] Preferably, the backwashing hole and the backwashing control hole are arranged in the limiting step one. The backwashing hole is arranged in the outer circle below the injection-production string connection thread, and sealing ring grooves one and sealing rings are arranged on both the upper and lower sides of the backwashing hole; the backwashing control hole is arranged at the root of the limiting step one, and at least one sealing ring groove two is arranged on the outer circle at the top of the limiting step two; the outer diameter of the limiting step three is the largest, and a buttress thread is machined on this outer circle. A middle locking ring connection thread is arranged at the lower end of the outer circle of the limiting step four; a spare part connection thread is machined at the lower part of the limiting step five.

[0018] Preferably, the middle locking ring is provided with a central hole and internal threads on its inner circle. After the middle locking ring is sleeved outside the inner cylinder, the internal threads on its inner circle are threadedly connected to the middle locking ring connection thread; the sealing assembly is a combined seal, which at least includes one sealing ring and protective rings made of polytetrafluoroethylene respectively installed on both sides of the sealing ring. The outer diameter of the sealing ring is larger than the inner diameter of the seal sealing cavity in the preset lower outer cylinder; the sealing pressure ring is threadedly connected to the spare part connection thread at the lower part of the limiting step five, and a lower pressure ring and a soluble plug are also connected below the sealing pressure ring.

[0019] Preferably, the inner circle of the working cylinder sliding cylinder is machined with two inner diameters that are smaller at the top and larger at the bottom. The smaller inner diameter section is installed outside the limiting step one of the inner cylinder, and the larger inner diameter section is installed outside the limiting step two; the two inner diameters of the inner circle of the working cylinder sliding cylinder are both precision-machined surfaces; in the normal working state of the working cylinder sliding cylinder, the smaller inner diameter section blocks the backwashing hole, and the larger inner diameter section communicates with the backwashing control hole.

[0020] Preferably, the leather cup is installed inside the sliding cylinder of the flow-limiting device and its lower part is located between the sliding cylinder of the flow-limiting device and the upper pushing cylinder. Sealing elements are installed in the sealing surfaces on the outer circumference of the central pipe; the staggered converging flow channels are composed of a main channel groove processed in the center of the flow-limiting plate and auxiliary channel grooves communicated with the main channel groove; the limiting plate installation grooves provided on the outer wall of the central pipe and the flow-limiting plates are provided in more than one set, and the flow-limiting plates are welded in the limiting plate installation grooves.

[0021] Preferably, the main channel groove is a straight groove directly leading to both ends of the flow-limiting plate body; the auxiliary channel grooves are arranged on both sides of the main channel groove and the flow channel shape is an arc-shaped downward slope type, and the auxiliary channel grooves arranged on both sides are staggeredly connected end to end in the main channel groove.

[0022] Preferably, both the locking ring and the flow-limiting device locking ring are broken rings provided with axial cuts. The cuts provided axially are oblique cuts or vertical cuts and the oblique angle is set between 1 degree and 89 degrees; the inner diameter of the locking ring in the natural state is smaller than the outer diameter of the central pipe section where it is located; the outer circumference of the flow-limiting device locking ring is processed with a buttress thread and can cooperate with the buttress thread processed in the inner circumference of the upper pushing cylinder.

[0023] Preferably, the upper pushing cylinder is a non-uniform diameter cylinder body, provided with an upper cylinder body and a back-off prevention thread arranged in the lower cylinder body. The inner diameter of the upper cylinder body is smaller than the inner diameter of the lower cylinder body. At least one liquid-assisted sealing and passing groove is arranged on the outer wall of the upper cylinder body, and the liquid-assisted sealing and passing groove communicates with the top of the upper cylinder body; the inner circumference of the lower cylinder body of the upper pushing cylinder is provided with a back-off prevention thread, and the back-off prevention thread is a buttress thread type and can cooperate with the buttress thread of the outer circumference of the flow-limiting device locking ring.

[0024] Preferably, a continuous thread is processed on the outer circumference of the central pipe below the limiting step of the upper pushing cylinder, and the washing aid and blowout prevention mechanism can be threadedly connected through this continuous thread.

[0025] Preferably, the washing aid and blowout prevention mechanism is provided with an upper outer cylinder of the flow-limiting device, a lower outer cylinder of the flow-limiting device, a lower pushing cylinder, a flow-limiting device spring and a limiting cylinder. The two ends of the upper outer cylinder of the flow-limiting device are respectively threadedly connected with the continuous thread in the central pipe and the lower outer cylinder of the flow-limiting device. The lower pushing cylinder and the flow-limiting device spring are installed inside the lower outer cylinder of the flow-limiting device. The limiting cylinder is installed below the flow-limiting device spring and is threadedly connected with the lower outer cylinder of the flow-limiting device; at least one washing aid and blowout prevention passing groove is arranged in the limiting cylinder.

[0026] Preferably, the inner circumference of the lower outer cylinder of the flow-limiting device is a non-uniform diameter inner circumference, and the internal threads at both ends are respectively threadedly connected with the upper outer cylinder of the flow-limiting device and the limiting cylinder; an inner cone mating surface is arranged between the two non-uniform diameter inner circumferences of the lower outer cylinder of the flow-limiting device, and the inner cone mating surface is a lower inclined surface.

[0027] Preferably, the lower push cylinder is a non-uniform diameter cylinder. The outer wall of the upper part of the lower push cylinder is an outer cone mating surface, which is an upper inclined surface and can cooperate with the inner cone mating surface in the lower outer cylinder of the flow limiting device. At least one sealing ring groove is machined in the outer cone mating surface; the flow limiting device spring is installed in the inner cavity below the spring limiting step in the lower push cylinder.

[0028] Preferably, the upper outer circle of the limiting cylinder is provided with an external thread and can be threadedly connected to the lower outer cylinder of the flow limiting device; the washing aid anti-spray overflow groove provided on the outer wall of the limiting cylinder is a vertically through groove and at least one is provided; the upper outer cylinder of the flow limiting device is a non-uniform diameter cylinder, and the internal and external threads in the cylinders at the upper and lower ends can be threadedly connected to the continuation thread of the central pipe and the lower outer cylinder of the flow limiting device respectively. The lower inner cavity of the upper outer cylinder of the flow limiting device after being connected to the central pipe is communicated with the limiting plate installation groove.

[0029] Preferably, centralizers are connected in the straight and inclined well high-frequency injection and production pipe string on both the upper and lower sides of the downhole annulus flow limiting device, and flow nipples are connected in the straight and inclined well high-frequency injection and production pipe string on both the upper and lower sides of the downhole safety valve; the tubing includes small-diameter tubing and large-diameter tubing. The centralizers and the downhole annulus flow limiting device are connected in series in the small-diameter tubing, and the downhole safety valve and the flow nipples are connected in series in the large-diameter tubing.

[0030] The completion method applied to the above-mentioned compressed air energy storage straight and inclined well high-frequency injection and production pipe string includes the following steps: A. Connect the preset working cylinder in the downhole combined sealing device in series at a predetermined position in the completion string and lower it into the well for completion; B. Connect the sealing working cylinder to the lower end of the injection and production string, lower it into the well, and press down the sealing working cylinder through the injection and production string to realize the anchoring and sealing of the injection and production string and the completion string; C. Pressurize positively to set the downhole annulus flow limiting device, and at the same time test whether the injection and production string leaks; D. If there is no leakage in the injection and production string during the pressure test, start the downhole annulus flow limiting device; E. After starting the downhole annulus flow limiting device, continue to pressurize for backwashing the well and verify whether the downhole combined sealing device works properly; F. After verifying that the downhole combined sealing device works properly, inject casing protection fluid; G. Reverse the well washing pipeline to the normal well washing process, let it stand for a period of time, then apply ground pressure to break the soluble plug in the downhole combined sealing device to complete the completion of the straight and inclined well high-frequency injection and production pipe string.

[0031] Compared with the prior art, the present invention has the following advantages: (1) The injection-production string provided by the present invention realizes the efficient anchoring of the injection-production string by adopting a downhole combined sealing device, solving the problem that the slips in the previous packer anchoring are prone to looseness and failure under the condition of high-frequency injection-production stress alternation. At the same time, the injection-production string provided by the present invention can also be used in wells for injecting carbon dioxide.

[0032] (2) The injection-production string provided by the present invention has a backwashing function. After the normal injection-production cycle ends, the scale and wax in the tubing can be cleaned by back-circulating the washing fluid with a cleaning function, realizing maintenance without pulling the string, reducing the conventional operation cost and time, prolonging the service life of the injection-production string, and improving the working efficiency of the gas storage reservoir.

[0033] (3) The inner cylinder of the sealing working barrel in the present invention has a backwashing function by itself. When a blowout occurs, it is easier to kill the well by back-circulation, effectively reducing the difficulty of killing the well during a blowout and improving the safety factor of the injection-production well in terms of process principle.

[0034] (4) Compared with the packer used in the existing string, the working principle of the downhole combined sealing device in the present invention is simple and reliable. While improving the anchoring and sealing ability, it enhances the safety of the entire string and tools. The provided backwashing process channel significantly reduces the probability of downhole accidents caused by scale blockage or wax blockage in the string after the injection-production well is put into production.

[0035] (5) The injection-production string provided by the present invention realizes the requirement of blowout prevention in the casing-tubing annulus while ensuring the smoothness of the backwashing channel of the injection-production string by adopting a downhole annulus flow-limiting device, improving the safety of the entire injection-production string.

[0036] (6) Through the backwashing process channel of the present invention, it becomes possible to inject and replace the casing protection fluid infinitely, which can well prevent corrosion in the casing-tubing annulus of the well, reduce the requirement for the material of the completion casing, and greatly save the completion cost.

[0037] (7) The completion method provided by the present invention can test the reliability of the injection-production string in each step of the completion process, preventing the injection-production string with potential hazards from entering the well.

[0038] In summary, while improving the safety of the entire string, the present invention provides a backwashing process channel, significantly reducing the probability of downhole accidents caused by scale blockage in the tubing and the requirement for the material of the casing, prolonging the service life of the injection-production string, and improving the working efficiency of the gas storage reservoir. It has good economic and social benefits and has great promotion potential. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The accompanying drawings are used to provide a further understanding of the present invention, and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation to the present invention. In the drawings: Figure 1 It is a schematic diagram of the overall structure of the injection-production string in the present invention.

[0040] Figure 2 It is a schematic diagram of the structure of the preset working barrel in the present invention.

[0041] Figure 3 is Figure 2 a schematic diagram of the structure of the upper outer barrel in

[0042] Figure 4 is Figure 2 a schematic diagram of the structure of the locking ring in

[0043] Figure 5 It is a schematic diagram of the structure of the sealing working barrel in the present invention.

[0044] Figure 6 is Figure 5 a schematic diagram of the structure of the inner barrel in

[0045] Figure 7 is Figure 1 a schematic diagram of the structure of the oil-casing annulus flow-limiting device in

[0046] Figure 8 is Figure 7 a schematic diagram of the structure of the central pipe in

[0047] Figure 9 is Figure 7 a schematic diagram of the structure of the upper push barrel in

[0048] Figure 10 is Figure 7 a schematic diagram of the structure of the flow-limiting plate in

[0049] Figure 11 is Figure 7 a schematic diagram of the structure of the lower outer barrel in

[0050] Figure 12 is Figure 7 a schematic diagram of the structure of the lower push barrel in

[0051] Figure 13 is Figure 7 a schematic diagram of the structure of the limiting barrel in

[0052] In the figure: Preset working barrel 1, sealing working barrel 2, small-diameter oil pipe 3, downhole annulus flow-limiting device 4, large-diameter oil pipe 5, downhole safety valve 6, flow short joint 7, centralizer 8; Prefabricated working barrel 1: Prefabricate upper outer barrel 1-1 and upper outer barrel torque transmission spline 1-11; Prefabricate locking ring 1-2 and locking ring torque transmission spline 1-21; Prefabricate lower outer barrel 1-3.

[0053] Sealing working barrel 2: Inner barrel 2-1, backwashing hole 2-101, sealing ring groove 1 2-102, limiting step 1 2-103, backwashing control hole 2-104, sealing ring groove 2 2-105, limiting step 2 2-106, limiting step 3 2-107, limiting step 4 2-108, middle locking ring connection thread 2-109, limiting step 5 2-110; Upper locking ring 2-2, working barrel sliding barrel 2-3, working barrel spring 2-4, disc spring 2-5, disc spring top ring 2-6, sealing insertion barrel 2-7, middle locking ring 2-8, working barrel limiting ring 2-9, sealing assembly 2-10, sealing pressing ring 2-11, lower pressing ring 2-12; Downhole annulus flow-limiting device 4, upper joint 4-1, central tube 4-2, limiting plate installation groove 4-2-1, setting packer hole 4-2-2, locking ring groove 4-2-3, setting packer boosting hole 4-2-4, locking ring installation groove 4-2-5, upper push barrel limiting step 4-2-6, continuous connection thread 4-2-7, flow-limiting device sliding barrel 4-3, locking ring 4-4, flow-limiting device limiting ring 4-5, leather cup 4-6, upper push barrel 4-7, anti-backoff thread 4-7-1, upper cylinder body 4-7-2, assisting setting packer liquid passing groove 4-7-3, flow-limiting device locking ring 4-8, flow-limiting device upper outer barrel 4-9, flow-limiting plate 4-10, main channel groove 4-10-1, auxiliary channel groove 4-10-2, flow-limiting device lower outer barrel 4-11, inner cone mating surface 4-11-1, lower push barrel 4-12, outer cone mating surface 4-12-1, flow-limiting device spring 4-13, limiting cylinder 4-14, assisting washing and blowout prevention liquid passing groove 4-14-1. Detailed implementation manners

[0054] The attached drawings are only for reference and illustration purposes and are not intended to limit the protection scope of the present invention. The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the attached drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0055] In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the attached drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention and are not used to limit the present invention.

[0056] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention. In addition, in the description of the present invention, the meaning of "a plurality of" is two or more, unless otherwise specifically defined.

[0057] See Figures 1-13 , a vertical and inclined well high-frequency injection and production string for compressed air energy storage, which is provided with an oil pipe and a downhole safety valve 6. Among them: the injection and production string is successively connected with a downhole combined sealing device, a downhole annulus flow-limiting device 4 and a downhole safety valve 6 from bottom to top through the oil pipe. The downhole combined sealing device is formed by inserting a preset working cylinder 1 and a sealing working cylinder 2; in the preset working cylinder 1, a preset locking ring 1-2 with a buttress thread is installed between a preset upper outer cylinder 1-1 and a preset lower outer cylinder 1-3. The preset upper outer cylinder 1-1 is connected to the preset lower outer cylinder 1-3, and the preset working cylinder 1 is pre-lowered into a preset position in the well together with the completion string; the sealing working cylinder 2 includes a sealing component mainly composed of a sealing insertion cylinder 2-7 and a sealing assembly 2-10 and an inner cylinder 2-1; the inner cylinder 2-1 is provided with a backwashing hole 2-101 and a backwashing control hole 2-104, and the outer circle of the limiting step three 2-107 in the inner cylinder 2-1 is machined with a buttress thread; the sealing working cylinder 2 is connected to the lower end of the injection and production string and lowered into the preset working cylinder 1. The inner cylinder 2-1 cooperates with the buttress thread in the preset locking ring 1-2. The sealing insertion cylinder 2-7 seals the sealing insertion cavity of the preset lower outer cylinder 1-3, and the sealing assembly 2-10 seals the sealing cavity of the seal of the preset lower outer cylinder 1-3; the downhole annulus flow-limiting device 4 is provided with a cup leather 4-6 and a central tube 4-2. A flow-limiting plate 4-10 with an interleaved converging flow channel is fixed in a flow-limiting plate installation groove 4-2-1 in the wall of the central tube 4-2, and a setting hole 4-2-2 and a setting boosting hole 4-2-4 are arranged in the wall without the flow-limiting plate installation groove 4-2-1; above the upper pushing cylinder limiting step 4-2-6 of the central tube 4-2, a flow-limiting device sliding cylinder 4-3, a cup leather 4-6 and an upper pushing cylinder 4-7 are successively installed from top to bottom; a flow-limiting device limiting ring 4-5 with a locking ring 4-4 installed is installed in the flow-limiting device sliding cylinder 4-3 above the cup leather 4-6, and the locking ring 4-4 is installed in a locking ring groove 4-2-3 on the outer circle of the central tube 4-2; the upper pushing cylinder 4-7 is in buttress thread cooperation with a flow-limiting device locking ring 4-8 installed in a locking ring installation groove 4-2-5 of the central tube 4-2.

[0058] The downhole combined sealing device in the present invention consists of two parts, namely a preset working cylinder 1 and a sealing working cylinder 2, which are used in cooperation. The inner wall of the preset locking ring 1-2 in the preset working cylinder 1 is machined with a buttress thread, and the upper end is also machined with a locking ring torque transmission spline 1-21 that matches the upper outer cylinder torque transmission spline 1-11 in the preset upper outer cylinder 1-1. The two achieve the torque transmission function through spline fitting. The buttress thread on the inner wall of the preset locking ring 1-2 is closely fitted with the buttress thread in the inner cylinder 2-1 to achieve the axial one-way locking function.

[0059] According to the technological requirements, when the cup 4-6 in the downhole annulus flow-limiting device 4 is set, when the liquid flow passes through the setting hole 4-2-2 in the tubing and enters the gap between the flow-limiting device sliding cylinder 4-3 and the flow-limiting device limiting ring 4-5, after pushing the flow-limiting device sliding cylinder 4-3 to move upward, the cup 4-6 is released from the flow-limiting device sliding cylinder 4-3; as the liquid entering through the setting boosting hole 4-2-4 makes the upper pushing cylinder 4-7 move upward and presses the cup 4-6 tightly in the tubing-casing annulus, the sealing between the flow-limiting device sliding cylinder 4-3 and the casing is achieved. At this time, the backwashing operation can be carried out through the staggered converging flow channels in the flow-limiting plate 4-10.

[0060] When the bottom-hole pressure rises and a blowout occurs, the well fluid surges upward through the staggered converging flow channels in the flow-limiting plate 4-10 below the device of the present invention and is blocked, effectively slowing down the flow velocity of the well fluid and weakening the intensity of the blowout, thus winning precious time for the blowout control work on the ground.

[0061] The flow-limiting plate 4-10 in the device is provided with staggered converging flow channels and is fixed in the flow-limiting plate installation groove 4-2-1 in the wall of the central tube 4-2. The setting hole 4-2-2 and the setting boosting hole 4-2-4 are arranged in the wall of the central tube 4-2 without the flow-limiting plate installation groove 4-2-1.

[0062] The cup 4-6 is installed in the flow-limiting device sliding cylinder 4-3 and the lower part is located between the flow-limiting device sliding cylinder 4-3 and the upper pushing cylinder 4-7. The flow-limiting device limiting ring 4-5 installed with the locking ring 4-4 is installed in the flow-limiting device sliding cylinder 4-3 above the cup 4-6; the locking ring 4-4 installed in the locking ring groove 4-2-3 on the outer circle of the central tube 4-2 locks the flow-limiting device limiting ring 4-5 at the inner top end of the flow-limiting device sliding cylinder 4-3 outside the central tube 4-2; the flow-limiting device locking ring 4-8 is installed in the locking ring installation groove 4-2-5 of the central tube 4-2 and is in buttress thread fit with the upper pushing cylinder 4-7. The flow-limiting device locking ring 4-8 is fixed in the locking ring installation groove 4-2-5 and cannot move axially. The upper pushing cylinder 4-7 can move upward along the flow-limiting device locking ring 4-8 to expand the cup 4-6 and seal the annulus between the flow-limiting device sliding cylinder 4-3 and the casing.

[0063] The downhole annulus flow-limiting device 4 can not only backwash the well while using the cup packing 4-6 to seal the oil casing annulus, but also throttle and limit the flow of the upwelling well fluid through the flow-limiting plate 4-10. It is connected to the injection-production string through the upper sub 4-1. This device has both the function of backwashing the well and the function of limiting the blowout and throttling.

[0064] When a blowout occurs in the downhole string of the gas storage injection-production well, the downhole annulus flow-limiting device 4 can gain time for controlling the blowout of the gas storage injection-production well, add a safety guarantee, avoid the adverse consequences brought by the blowout, improve the economic benefits, and has remarkable use effects. The present invention can also be used in conventional oil production wells.

[0065] Based on the above-mentioned first embodiment, the present invention also has the following embodiments: A preferred embodiment: The sealing working barrel 2 is further provided with an upper locking ring 2-2, a working barrel sliding barrel 2-3, a working barrel spring 2-4, a disc spring 2-5, a middle locking ring 2-8 and a sealing pressing ring 2-11. The upper locking ring 2-2, the working barrel sliding barrel 2-3 and the working barrel spring 2-4 are sequentially installed above the third limiting step 2-107 from top to bottom; the disc spring 2-5, the sealing insertion barrel 2-7, the middle locking ring 2-8, the sealing assembly 2-10 and the sealing pressing ring 2-11 are sequentially installed below the third limiting step 2-107 from top to bottom. After being connected to the preset working barrel 1, the sealing working barrel 2 is provided with a disc spring 2-5 and a disc spring top ring 2-6 below the third limiting step 2-107 which is tightly connected with the buttress thread. When the injection-production string is pressed down, due to the limitation of the preset working barrel 1, the disc spring top ring 2-6 can effectively transmit the axial pressure, compress the disc spring 2-5, store a certain tonnage of pressure, and prevent the buttress thread between the preset working barrel 1 and the sealing working barrel 2 from creeping within the range of one pitch. A middle locking ring 2-8 threadedly connected to the inner barrel 2-1 is further arranged below the sealing insertion barrel 2-7 to limit and tightly press the sealing insertion barrel 2-7.

[0066] A preferred embodiment: The top of the ring body of the preset locking ring 1-2 is provided with a locking ring torque transmission spline 1-21. The lower inner circle of the preset locking ring 1-2 is provided with a buttress thread. The preset locking ring 1-2 is an open ring axially provided with a straight or inclined through groove; the preset upper outer barrel 1-1 is a non-uniform diameter cylindrical body. The upper inner cavity of the preset upper outer barrel 1-1 is provided with an internal thread for connecting with the completion string, the lower part is a threaded inner cavity, and the middle inner cavity is provided with a locking ring limiting step and an upper outer barrel torque transmission spline 1-11 is arranged on the inner circle of the locking ring limiting step; the upper outer barrel torque transmission spline 1-11 can cooperate with the locking ring torque transmission spline 1-21 at the top of the ring body of the preset locking ring 1-2, and after the cooperation, the preset locking ring 1-2 is exactly located in the locking ring installation cavity between the locking ring limiting step and the lower threaded inner cavity.

[0067] A preferred embodiment: The preset lower outer cylinder 1-3 is a non-uniform diameter cylinder, and external threads are provided on the outer circles at both ends of the preset lower outer cylinder 1-3, and can be threadedly connected to the internal threads in the threaded inner cavity of the lower part of the preset upper outer cylinder 1-1 and the lower casing in the completion string respectively; the upper inner cavity of the preset lower outer cylinder 1-3 is a sealed insertion cylinder sealing cavity, and the lower inner cavity is a seal sealing cavity; the sealed insertion cylinder sealing cavity is a conical cavity.

[0068] A preferred embodiment: The sealed insertion cylinder 2-7 can be made of rubber or polymer material, soft metal or shape memory alloy. The lower outer circle of the sealed insertion cylinder 2-7 is a conical outer circle, and this conical outer circle cooperates with the sealed insertion cylinder sealing cavity of the preset lower outer cylinder 1-3; a disc spring top ring 2-6 is also installed between the disc spring 2-5 and the sealed insertion cylinder 2-7. Polymer materials include engineering resins and engineering plastics, and soft metals include copper and lead. The disc spring top ring 2-6 can provide protection for the top end of the sealed insertion cylinder 2-7, and during operation, the disc spring top ring 2-6 can provide a loosening-preventing tightening force for the bayonet joint, improving and strengthening the tightening effect of the disc spring 2-5 on the sealed insertion cylinder 2-7, and further improving the sealing effect.

[0069] A preferred embodiment: The inner cylinder 2-1 is a non-uniform diameter cylinder, and injection-production string connection threads and spare part connection threads are respectively arranged at the upper and lower ends of the inner cylinder 2-1; limiting steps one 2-103, limiting steps two 2-106, limiting steps three 2-107, limiting steps four 2-108 and limiting steps five 2-110 are sequentially arranged on the outer circle of the inner cylinder 2-1 from top to bottom, and the outer circles of the limiting steps one 2-103, limiting steps two 2-106, limiting steps three 2-107, limiting steps four 2-108 and limiting steps five 2-110 are all precision-machined outer circle surfaces.

[0070] A preferred embodiment: The backwashing hole 2-101 and the backwashing control hole 2-104 are arranged in the limiting step one 2-103. The backwashing hole 2-101 is arranged in the outer circle below the injection-production string connection thread, and sealing ring grooves one and sealing rings are arranged on both the upper and lower sides of the backwashing hole 2-101; the backwashing control hole 2-104 is arranged at the root of the limiting step one 2-103, and at least one sealing ring groove two 2-105 is arranged on the outer circle at the top of the limiting step two 2-106; the outer diameter of the limiting step three 2-107 is the largest, and bayonet joints are machined on this outer circle. A middle lock ring connection thread 2-109 is arranged at the lower end of the outer circle of the limiting step four 2-108; spare part connection threads are machined at the lower part of the limiting step five 2-110.

[0071] A preferred embodiment: The middle locking ring 2-8 is provided with a central hole and internal threads on its inner circle. After the middle locking ring 2-8 is sleeved outside the inner cylinder 2-1, the internal threads on its inner circle are threadedly connected to the connecting threads 2-109 of the middle locking ring, providing support for the sealing insertion cylinder 2-7; The sealing assembly 2-10 is a combined seal, which at least includes a sealing ring and protective rings made of polytetrafluoroethylene respectively installed on both sides of the sealing ring. The outer diameter of the sealing ring is greater than the inner diameter of the sealing cavity of the sealing member in the preset lower outer cylinder 1-3; The sealing pressure ring 2-11 is threadedly connected to the connecting threads of the spare parts at the lower part of the limiting step five 2-110, and a lower pressure ring 2-12 and a soluble plug are also connected below the sealing pressure ring 2-11. It further provides a pressing and locking force for the sealing assembly 2-10 and the sealing pressure ring 2-11 and prevents the sealing pressure ring 2-11 from loosening.

[0072] A preferred embodiment: The inner circle of the working cylinder sliding cylinder 2-3 is processed with two inner diameters that are smaller at the top and larger at the bottom. The small inner diameter section is installed outside the limiting step one 2-103 of the inner cylinder 2-1, and the large inner diameter section is installed outside the limiting step two 2-106; Both inner diameters of the inner circle of the working cylinder sliding cylinder 2-3 are precision machined surfaces; In the normal working state of the working cylinder sliding cylinder 2-3, the small inner diameter section blocks the backwashing hole 2-101, and the large inner diameter section communicates with the backwashing control hole 2-104. During the processes of backwashing the well, pumping casing protection fluid into the annulus between the casing and the tubing, and reverse circulation killing the well, under the action of pressure difference, the working cylinder sliding cylinder 2-3 moves downward to expose the backwashing hole 2-101, forming a backwashing channel; The backwashing control hole 2-104 discharges the liquid in the inner cavity of the working cylinder sliding cylinder 2-3 into the tubing to prevent the formation of a dead cavity when the working cylinder sliding cylinder 2-3 moves downward and hinder the downward movement of the working cylinder sliding cylinder 2-3. After the backwashing operation is completed, under the pushing force of the working cylinder spring 2-4, the working cylinder sliding cylinder 2-3 moves upward and closes the backwashing hole 2-101, closing the oil-casing communication channel.

[0073] In the downhole combined sealing device, in addition to the sealing insertion cylinder 2-7 being able to achieve sealing between the preset working cylinder 1 and the sealing working cylinder 2, a sealing assembly 2-10 is also provided below it, which at least has a sealing ring and two protective rings, adding another sealing barrier to this device, ensuring the sealing effect of this device, extending the service life of this sealing tool and the injection-production string, and reducing the production cost.

[0074] The working principle of the downhole combined sealing device is that first, the preset working cylinder 1 is fixed downhole, and then the sealing working cylinder 2 is connected to the lowest end of the injection-production string and lowered into the well by the injection-production string.

[0075] After the sealing working barrel 2 is inserted into the preset working barrel 1, the sealing insert barrel 2-7 and the sealing assembly 2-10 cooperate with the corresponding sealing surfaces in the preset working barrel 1 to achieve the sealing of the annulus between the tubing and the casing. At the same time, the buttress threads on the outer wall of the limiting step three 2-107 of the inner barrel 2-1 in the sealing working barrel 2 cooperate with the preset locking ring 1-2 in the preset working barrel 1 to achieve axial anti-retreat locking. In addition, a part of the pressing tonnage of the injection-production string is transmitted to the disc spring 2-5 through the sealing insert barrel 2-7. The disc spring 2-5 compresses and stores a certain tonnage of pressure to prevent the buttress threads from creeping within the range of one pitch.

[0076] The disc spring 2-5 stores energy due to the downward pressure of the injection-production string, which can always ensure the tension force of the cooperation between the buttress threads in the preset working barrel 1 and the sealing working barrel 2, and reduce the damage of the sealing assembly 2-10 caused by the creeping of the injection-production string. The sliding sleeve 2-3 is in a closed state during normal operation. When the injection-production string needs to conduct reverse circulation well washing, pump in casing protection fluid or encounter downhole overflow accidents, washing fluid or kill fluid can be pumped into the annulus between the tubing and the casing to provide a process channel for the cleaning or kill operation of the injection-production string.

[0077] A preferred embodiment: see Figure 7 、 Figure 8 and Figure 10 , the cup leather 4-6 is installed in the flow-limiting device sliding barrel 4-3 and the lower part is located between the flow-limiting device sliding barrel 4-3 and the upper pushing barrel 4-7. Sealing elements are installed in the sealing surfaces of the outer circle of the central tube 4-2; the staggered converging flow channel is composed of a main channel groove 4-10-1 processed in the center of the flow-limiting plate 4-10 and auxiliary channel grooves 4-10-2 communicated with the main channel groove 4-10-1; the limiting plate installation grooves 4-2-1 provided on the outer wall of the central tube 4-2 and the flow-limiting plates 4-10 are provided in more than one set, and the flow-limiting plates 4-10 are welded in the limiting plate installation grooves 4-2-1.

[0078] A preferred embodiment: the main channel groove 4-10-1 is a straight groove directly leading to both ends of the plate body of the flow-limiting plate 4-10; the auxiliary channel grooves 4-10-2 are arranged on both sides of the main channel groove 4-10-1 and the flow channel shape is arc-shaped and inclined downward, and the auxiliary channel grooves 4-10-2 arranged on both sides are staggeredly connected end to end in the main channel groove 4-10-1. The staggered converging flow channel in the flow-limiting plate 4-10 can also have other forms and composition methods. In principle, it is to make the liquid flow from above the invention smooth and the liquid flow from below the invention difficult to return upward.

[0079] Preferred embodiment: Both the lock ring 4-4 and the flow-limiting device lock ring 4-8 are split rings with axial cuts. The cuts provided axially are oblique cuts or vertical cuts, and the oblique angle is set between 1 degree and 89 degrees. The inner diameter of the lock ring 4-4 in its natural state is smaller than the outer diameter of the corresponding section of the central tube 4-2. This is mainly considered for installation. The inner diameter of the lock ring 4-4 is slightly smaller than the outer diameter of the upper part of the central tube 4-2. After installation and restoration, it can still be clamped tightly in the lock ring groove 4-2-3. The outer circle of the flow-limiting device lock ring 4-8 is machined with a buttress thread and can cooperate with the buttress thread machined on the inner circle of the upper push cylinder 4-7.

[0080] Preferred embodiment: The upper push cylinder 4-7 is a non-uniform diameter cylinder, provided with an upper cylinder body 4-7-2 and a backstop thread 4-7-1 arranged in the lower cylinder body. The inner diameter of the upper cylinder body 4-7-2 is smaller than that of the lower cylinder body. At least one liquid-assisted sealing and passing groove 4-7-3 is arranged on the outer wall of the upper cylinder body 4-7-2, and the liquid-assisted sealing and passing groove 4-7-3 communicates with the top of the upper cylinder body 4-7-2. The inner circle of the lower cylinder body of the upper push cylinder 4-7 is provided with a backstop thread 4-7-1, and the backstop thread 4-7-1 is a buttress thread type and can cooperate with the buttress thread on the outer circle of the flow-limiting device lock ring 4-8.

[0081] Preferred embodiment: The outer circle of the central tube 4-2 below the upper push cylinder limit step 4-2-6 is machined with a connecting thread 4-2-7, and through this connecting thread 4-2-7, it can be threadedly connected with the washing and blowout prevention mechanism.

[0082] Preferred embodiment: Refer to Figure 12 , the washing and blowout prevention mechanism is provided with a flow-limiting device upper outer cylinder 4-9, a flow-limiting device lower outer cylinder 4-11, a lower push cylinder 4-12, a flow-limiting device spring 4-13 and a limit cylinder 4-14. The two ends of the flow-limiting device upper outer cylinder 4-9 are respectively threadedly connected with the connecting thread 4-2-7 in the central tube 4-2 and the flow-limiting device lower outer cylinder 4-11. The lower push cylinder 4-12 and the flow-limiting device spring 4-13 are installed in the flow-limiting device lower outer cylinder 4-11. The limit cylinder 4-14 is installed below the flow-limiting device spring 4-13 and is threadedly connected with the flow-limiting device lower outer cylinder 4-11. At least one washing and blowout prevention liquid passing groove 4-14-1 is arranged in the limit cylinder 4-14. The water and liquid coming from below the annulus flow-limiting device cannot enter above the annulus flow-limiting device through the lower push cylinder 4-12, and the water and liquid coming from above the annulus flow-limiting device can push open the lower push cylinder 4-12 tightened by the flow-limiting device spring 4-13 and enter below the annulus flow-limiting device.

[0083] Preferred embodiment: Refer to Figure 11, the inner circle of the lower outer cylinder 4-11 of the flow-limiting device is a non-uniform-diameter inner circle, and the internal threads at both ends are respectively threadedly connected to the upper outer cylinder 4-9 and the limiting cylinder 4-14 of the flow-limiting device; an inner conical mating surface 4-11-1 is provided between the two outer non-uniform-diameter inner circles of the lower outer cylinder 4-11 of the flow-limiting device, and this inner conical mating surface 4-11-1 is a lower inclined surface.

[0084] A preferred embodiment: Refer to Figure 12 , the lower push cylinder 4-12 is a non-uniform-diameter cylindrical body, the upper outer wall of the lower push cylinder 4-12 is an outer conical mating surface 4-12-1, this outer conical mating surface 4-12-1 is an upper inclined surface and can cooperate with the inner conical mating surface 4-11-1 in the lower outer cylinder 4-11 of the flow-limiting device, and at least one sealing ring groove is machined in the outer conical mating surface 4-12-1; the flow-limiting device spring 4-13 is installed in the inner cavity below the spring limiting step 4-12-2 in the lower push cylinder 4-12.

[0085] A preferred embodiment: Refer to Figure 13 , the upper outer circle of the limiting cylinder 4-14 is provided with an external thread and can be threadedly connected to the lower outer cylinder 4-11 of the flow-limiting device; the washing-aid anti-spray overflow groove 4-14-1 provided in the outer wall of the limiting cylinder 4-14 is a through groove up and down and at least one is provided; the upper outer cylinder 4-9 of the flow-limiting device is a non-uniform-diameter cylindrical body, and the internal and external threads in the upper and lower ends of the cylindrical body can be respectively threadedly connected to the continuous thread 4-2-7 of the central pipe 4-2 and the lower outer cylinder 4-11 of the flow-limiting device, and the lower inner cavity of the upper outer cylinder 4-9 of the flow-limiting device after being connected to the central pipe 4-2 is communicated with the limiting plate installation groove 4-2-1. In the annulus flow-limiting device, sealing elements are provided in the sealing mating surfaces between components.

[0086] The washing-aid anti-spray mechanism connected to the lower part of the central pipe 4-2 adds an additional guarantee for the backwashing well of this device and the limited spraying and throttling during a blowout. The backwashing well water from above the device can increase the pump pressure, push open the lower push cylinder 4-12, and spray and flush into the oil-casing annulus from the washing-aid anti-spray overflow groove 4-14-1 for reverse circulation well washing.

[0087] When the downhole pressure increases and a blowout occurs, due to the sealing of the cup leather 4-6 and the internal and external conical mating surfaces in the lower outer cylinder 4-11 and the lower push cylinder 4-12 of the flow-limiting device, the incoming water and liquid cannot return upward from the washing-aid anti-spray overflow groove 4-14-1 of the limiting cylinder 4-14; if the washing-aid anti-spray mechanism fails due to some reason and the internal and external conical mating surfaces in the lower outer cylinder 4-11 and the lower push cylinder 4-12 of the flow-limiting device cannot be sealed and the one-way flow control function cannot be realized, the liquid flow can only pass through the staggered converging flow channels of the flow-limiting plate 4-10. When the liquid passes through the staggered converging flow channels, due to the impact of the liquid flow directions in the main channel groove 4-10-1 and the auxiliary channel groove 4-10-2 on each other, the upwelling flow rate and pressure are greatly reduced, buying more time for the ground staff to prevent blowout.

[0088] A preferred embodiment: Centralizers 8 are connected in the straight-inclined well high-frequency injection-production string on both the upper and lower sides of the downhole annulus flow-limiting device 4, and flow nipples 7 are connected in the straight-inclined well high-frequency injection-production string on both the upper and lower sides of the downhole safety valve 6; the tubing includes small-diameter tubing 3 and large-diameter tubing 5. The centralizer 8 and the downhole annulus flow-limiting device 4 are connected in series in the small-diameter tubing 3, and the downhole safety valve 6 and the flow nipple 7 are connected in series in the large-diameter tubing 5. Flow nipples 7 are installed at both ends of the downhole safety valve 6 to ensure the smooth flow of the fluid inside the pipe at this location. Centralizers 8 are installed at both ends of the downhole annulus flow-limiting device 4 to improve the centrality of the device and ensure the normal operation of the device. The tubing is divided into two diameters, the small-diameter tubing 3 is connected to the lower part of the string, and the large-diameter tubing 5 is connected to the upper part of the string. The pressure is adjusted by changing the flow area of the fluid to slow down the formation of scale.

[0089] The completion method applied to the above-mentioned straight-inclined well high-frequency injection-production string for compressed air energy storage includes the following steps: A. The preset working barrel 1 in the downhole combined sealing device is connected in series at a predetermined position in the completion string and lowered into the well for completion; B. The sealing working barrel 2 is connected to the lower end of the injection-production string and lowered into the well. By pressing down the sealing working barrel 2 through the injection-production string, the anchoring and sealing of the injection-production string and the completion string are realized; C. Pressurize positively to set the downhole annulus flow-limiting device, and at the same time test whether the injection-production string leaks; during this process, if there is a leak, rotate the string clockwise to pull it out and replace the injection-production string; D. If the injection-production string does not leak during the pressure test, start the downhole annulus flow-limiting device 4; during this process, connect the casing valve pipeline to pressurize through the tubing-casing annulus to start the downhole annulus flow-limiting device 4. If the pressure drops suddenly, it proves that the start is successful; E. After starting the downhole annulus flow-limiting device 4, continue to pressurize for backwashing the well and verify whether the downhole combined sealing device works normally; during this process, if there is fluid flowing back at the wellhead tubing, it proves that the backwashing channel in the downhole combined sealing device is opened normally; then reverse the well-washing pipeline to the normal washing process for pressurization. If the pressure does not drop when it reaches the predetermined value, it proves that the backwashing channel in the downhole combined sealing device is automatically closed normally; F. After verifying that the downhole combined sealing device works normally, inject the casing protection fluid; during this process, reverse the well-washing pipeline to the backwashing process and inject a certain amount of casing protection fluid into the tubing-casing annulus; G. Reverse the well-washing pipeline to the normal well-washing process, let it stand for a period of time, and then pressurize on the ground to punch out the soluble plug in the downhole combined sealing device to complete the completion of the straight-inclined well high-frequency injection-production string. If there are any abnormal situations in the above technological steps, the injection-production string needs to be rotated clockwise to pull it out and replaced.

[0090] The working principle of the injection-production string is that after the normal injection-production cycle ends, scale-removing, rust-removing and paraffin-removing liquids are used to clean the inside of the injection-production string by means of backwashing the well, so as to prevent a large amount of scale from blocking the channels of the injection-production string due to the high intensity and frequency of injection-production air. At the same time, the annulus casing protection liquid is replaced, so as to reduce the cost and time of replacing the injection-production string, extend the service life of the injection-production string, and improve the utilization efficiency of the gas storage reservoir.

[0091] The embodiments described above are only typical embodiments, but the present invention is not limited to these embodiments, and those skilled in the art can make modifications without departing from the spirit and inspiration of the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the creative spirit and creative concept of the present invention shall be included within the protection scope of the present invention. Therefore, the protection scope is not limited to the foregoing description.

Claims

1. A vertical and inclined well high-frequency injection and production string for compressed air energy storage, which is provided with a tubing and a downhole safety valve (6). It is characterized in that The injection and production string is successively connected with a downhole combined sealing device, a downhole annulus flow-limiting device (4) and a downhole safety valve (6) from bottom to top through the tubing. The downhole combined sealing device is formed by inserting a pre-set working barrel (1) and a sealing working barrel (2). In the pre-set working barrel (1), a pre-set locking ring (1-2) with a buttress thread is installed between a pre-set upper outer barrel (1-1) and a pre-set lower outer barrel (1-3). The pre-set upper outer barrel (1-1) is connected to the pre-set lower outer barrel (1-3). The pre-set working barrel (1) is pre-lowered into a preset position in the well together with the completion string. The sealing working barrel (2) includes a sealing component mainly composed of a sealing insertion barrel (2-7) and a sealing assembly (2-10) and an inner barrel (2-1). The inner barrel (2-1) is provided with a backwashing hole (2-101) and a backwashing control hole (2-104). The outer circle of the limit step three (2-107) in the inner barrel (2-1) is machined with a buttress thread. The sealing working barrel (2) is connected to the lower end of the injection and production string and lowered into the pre-set working barrel (1). The inner barrel (2-1) is connected to the buttress thread in the pre-set locking ring (1-2). The sealing insertion barrel (2-7) seals the sealing insertion barrel cavity of the pre-set lower outer barrel (1-3), and the sealing assembly (2-10) seals the seal cavity of the pre-set lower outer barrel (1-3). The downhole annulus flow-limiting device (4) is provided with a cup leather (4-6) and a central pipe (4-2). A flow-limiting plate (4-10) with an interleaved converging flow channel is fixed in a flow-limiting plate installation groove (4-2-1) in the wall of the central pipe (4-2), and a setting hole (4-2-2) and a setting boosting hole (4-2-4) are arranged in the wall without the flow-limiting plate installation groove (4-2-1). Above the upper push barrel limit step (4-2-6) of the central pipe (4-2), a flow-limiting device sliding barrel (4-3), a cup leather (4-6) and an upper push barrel (4-7) are successively installed from top to bottom. A flow-limiting device limit ring (4-5) installed with a locking ring (4-4) is installed in the flow-limiting device sliding barrel (4-3) above the cup leather (4-6). The locking ring (4-4) is installed in a locking ring groove (4-2-3) on the outer circle of the central pipe (4-2). The upper push barrel (4-7) is matched with a flow-limiting device locking ring (4-8) installed in a locking ring installation groove (4-2-5) of the central pipe (4-2) through a buttress thread.

2. A vertical and inclined well high-frequency injection and production string for compressed air energy storage according to claim 1, It is characterized in that The sealing working barrel (2) is further provided with an upper locking ring (2-2), a working barrel sliding barrel (2-3), a working barrel spring (2-4), a disc spring (2-5), a middle locking ring (2-8) and a sealing pressing ring (2-11). The upper locking ring (2-2), the working barrel sliding barrel (2-3) and the working barrel spring (2-4) are sequentially installed above the third limiting step (2-107) from top to bottom; the disc spring (2-5), the sealing insertion barrel (2-7), the middle locking ring (2-8), the sealing assembly (2-10) and the sealing pressing ring (2-11) are sequentially installed below the third limiting step (2-107) from top to bottom.

3. The high-frequency injection-production string for a compressed air energy storage vertical and inclined well according to claim 2, characterized in that the top of the ring body of the preset locking ring (1-2) is provided with a locking ring torque transmission spline (1-21), the lower inner circle of the preset locking ring (1-2) is provided with a horse tooth thread, and the preset locking ring (1-2) is an open ring axially provided with a straight or inclined through groove; the preset upper outer barrel (1-1) is a non-uniform diameter cylindrical body, the upper inner cavity of the preset upper outer barrel (1-1) is provided with an internal thread for connecting with the completion string, the lower part is a threaded inner cavity, and the middle inner cavity is provided with a locking ring limiting step and an upper outer barrel torque transmission spline (1-11) is provided on the inner circle of the locking ring limiting step; the upper outer barrel torque transmission spline (1-11) can cooperate with the locking ring torque transmission spline (1-21) at the top of the ring body of the preset locking ring (1-2), and the preset locking ring (1-2) after cooperation is exactly located in the locking ring installation cavity between the locking ring limiting step and the lower threaded inner cavity.

4. The high-frequency injection-production string for a compressed air energy storage vertical and inclined well according to claim 3, characterized in that the preset lower outer barrel (1-3) is a non-uniform diameter cylindrical body, the outer circles at both ends of the preset lower outer barrel (1-3) are both provided with external threads and can be respectively threadedly connected with the internal thread in the threaded inner cavity of the lower part of the preset upper outer barrel (1-1) and the lower casing thread in the completion string; the upper inner cavity of the preset lower outer barrel (1-3) is a sealing insertion barrel sealing cavity, and the lower inner cavity is a seal sealing cavity; the sealing insertion barrel sealing cavity is a conical cavity.

5. The high-frequency injection-production string for a compressed air energy storage vertical and inclined well according to claim 1, characterized in that the sealing insertion barrel (2-7) can be made of rubber or polymer material, soft metal or shape memory alloy. The lower outer circle of the sealing insertion barrel (2-7) is a conical outer circle, and the conical outer circle cooperates with the sealing insertion barrel sealing cavity of the preset lower outer barrel (1-3); a disc spring top ring (2-6) is also installed between the disc spring (2-5) and the sealing insertion barrel (2-7).

6. The high-frequency injection-production string for a compressed air energy storage vertical and inclined well according to claim 5, characterized in that The inner cylinder (2-1) is a non-uniform diameter cylinder, and injection-production pipe string connection threads and spare part connection threads are respectively arranged at the upper and lower ends of the inner cylinder (2-1); the outer circle of the inner cylinder (2-1) is successively provided with a first limiting step (2-103), a second limiting step (2-106), a third limiting step (2-107), a fourth limiting step (2-108) and a fifth limiting step (2-110) from top to bottom. The outer circles of the first limiting step (2-103), the second limiting step (2-106), the third limiting step (2-107), the fourth limiting step (2-108) and the fifth limiting step (2-110) are all precision-machined outer circle surfaces.

7. A high-frequency injection-production pipe string for a compressed air energy storage vertical and inclined well as described in claim 6, characterized in that, the backwashing hole (2-101) and the backwashing control hole (2-104) are arranged in the first limiting step (2-103). The backwashing hole (2-101) is arranged in the outer circle below the injection-production pipe string connection thread, and a first sealing ring groove and a sealing ring are arranged on both the upper and lower sides of the backwashing hole (2-101); the backwashing control hole (2-104) is arranged at the root of the first limiting step (2-103), and at least one second sealing ring groove (2-105) is arranged on the outer circle at the top of the second limiting step (2-106); the outer diameter of the third limiting step (2-107) is the largest, and a buttress thread is machined on this outer circle. A middle lock ring connection thread (2-109) is arranged at the lower end of the outer circle of the fourth limiting step (2-108); a spare part connection thread is machined at the lower part of the fifth limiting step (2-110).

8. A high-frequency injection-production pipe string for a compressed air energy storage vertical and inclined well as described in claim 7, characterized in that, the middle lock ring (2-8) is provided with a central hole and an internal thread on its inner circle. After the middle lock ring (2-8) is sleeved outside the inner cylinder (2-1), the internal thread on its inner circle is threadedly connected with the middle lock ring connection thread (2-109); the sealing assembly (2-10) is a combined seal, which at least includes a sealing ring and protection rings made of polytetrafluoroethylene respectively installed on both sides of the sealing ring. The outer diameter of the sealing ring is larger than the inner diameter of the seal cavity of the seal in the preset lower outer cylinder (1-3); the sealing pressure ring (2-11) is threadedly connected with the spare part connection thread at the lower part of the fifth limiting step (2-110), and a lower pressure ring (2-12) and a soluble plug are also connected below the sealing pressure ring (2-11).

9. A high-frequency injection-production pipe string for a compressed air energy storage vertical and inclined well as described in claim 8, characterized in that, the inner circle of the working cylinder sliding cylinder (2-3) is machined with two inner diameters that are smaller at the top and larger at the bottom. The smaller inner diameter section is installed outside the first limiting step (103) of the inner cylinder (2-1), and the larger inner diameter section is installed outside the second limiting step (106); the two inner diameters of the inner circle of the working cylinder sliding cylinder (2-3) are both precision-machined surfaces; when the working cylinder sliding cylinder (2-3) is in a normal working state, the smaller inner diameter section thereof blocks the backwashing hole (2-101), and the larger inner diameter section is communicated with the backwashing control hole (2-104).

10. A vertical and inclined well high-frequency injection and production string for compressed air energy storage according to claim 1, characterized in that, the cup leather (4-6) is installed in the flow-limiting device sliding cylinder (4-3) and the lower part is located between the flow-limiting device sliding cylinder (4-3) and the upper push cylinder (4-7), and seals are installed in the sealing surfaces of the outer circle of the central pipe (4-2); the staggered converging flow channel is composed of a main channel groove (4-10-1) processed in the center of the flow-limiting plate (4-10) and auxiliary channel grooves (4-10-2) communicated with the main channel groove (4-10-1); the limiting plate mounting grooves (4-2-1) provided on the outer wall of the central pipe (4-2) and the flow-limiting plates (4-10) are provided in more than one set, and the flow-limiting plates (4-10) are welded in the limiting plate mounting grooves (4-2-1).

11. A vertical and inclined well high-frequency injection and production string for compressed air energy storage according to claim 10, characterized in that, the main channel groove (4-10-1) is a straight groove directly leading to both ends of the plate body of the flow-limiting plate (4-10); the auxiliary channel grooves (4-10-2) are arranged on both sides of the main channel groove (4-10-1) and the flow channel shape is arc-shaped and inclined downward, and the auxiliary channel grooves (4-10-2) arranged on both sides are staggeredly connected end to end in the main channel groove (4-10-1).

12. A vertical and inclined well high-frequency injection and production string for compressed air energy storage according to claim 11, characterized in that, both the locking ring (4-4) and the flow-limiting device locking ring (4-8) are broken rings provided with axial cuts, the cuts provided axially are oblique cuts or vertical cuts and the oblique angle is set between 1 degree and 89 degrees; the inner diameter of the locking ring (4-4) in the natural state is smaller than the outer diameter of the central pipe (4-2) section where it is located; the outer circle of the flow-limiting device locking ring (4-8) is processed with a buttress thread and can be matched with the buttress thread processed in the inner circle of the upper push cylinder (4-7).

13. A vertical and inclined well high-frequency injection and production string for compressed air energy storage according to claim 12, characterized in that, the upper push cylinder (4-7) is a non-uniform diameter cylinder body, provided with an upper cylinder body (4-7-2) and a back-off prevention thread (4-7-1) arranged in the lower cylinder body, the inner diameter of the upper cylinder body (4-7-2) is smaller than the inner diameter of the lower cylinder body, at least one sealing and liquid-passing groove (4-7-3) is arranged on the outer wall of the upper cylinder body (4-7-2), and the sealing and liquid-passing groove (4-7-3) communicates with the top of the upper cylinder body (4-7-2); the inner circle of the lower cylinder body of the upper push cylinder (4-7) is provided with a back-off prevention thread (4-7-1), and the back-off prevention thread (4-7-1) is a buttress thread type and can be matched with the buttress thread of the outer circle of the flow-limiting device locking ring (4-8).

14. A vertical and inclined well high-frequency injection and production string for compressed air energy storage according to claim 13, characterized in that, a continuous thread (4-2-7) is processed on the outer circle of the central pipe (4-2) below the upper push cylinder limiting step (4-2-6), and the continuous thread (4-2-7) can be threadedly connected with the washing and blowout prevention mechanism.

15. A vertical and inclined well high-frequency injection and production string for compressed air energy storage according to claim 14, characterized in that, The washing aid and anti - spraying mechanism is provided with an upper outer cylinder (4 - 9) of the flow - limiting device, a lower outer cylinder (4 - 11) of the flow - limiting device, a lower pushing cylinder (4 - 12), a spring (4 - 13) of the flow - limiting device, and a limiting cylinder (4 - 14). The two ends of the upper outer cylinder (4 - 9) of the flow - limiting device are respectively thread - connected to the continuous thread (4 - 2 - 7) in the central tube (4 - 2) and the lower outer cylinder (4 - 11) of the flow - limiting device. The lower pushing cylinder (4 - 12) and the spring (4 - 13) of the flow - limiting device are installed inside the lower outer cylinder (4 - 11) of the flow - limiting device. The limiting cylinder (4 - 14) is installed below the spring (4 - 13) of the flow - limiting device and is thread - connected to the lower outer cylinder (4 - 11) of the flow - limiting device; at least one washing - aid and anti - spraying liquid - passing groove (4 - 14 - 1) is provided in the limiting cylinder (4 - 14).

16. A high - frequency injection - production pipe string for a compressed - air energy - storage vertical - inclined well as described in claim 15, characterized in that, the inner circle of the lower outer cylinder (4 - 11) of the flow - limiting device is a non - equal - diameter inner circle, and the inner threads at both ends are respectively thread - connected to the upper outer cylinder (4 - 9) of the flow - limiting device and the limiting cylinder (4 - 14); an inner - cone mating surface (4 - 11 - 1) is arranged between the two non - equal - diameter inner circles of the lower outer cylinder (4 - 11) of the flow - limiting device, and this inner - cone mating surface (4 - 11 - 1) is a lower inclined surface.

17. A high - frequency injection - production pipe string for a compressed - air energy - storage vertical - inclined well as described in claim 16, characterized in that, the lower pushing cylinder (4 - 12) is a non - equal - diameter cylindrical body. The outer wall of the upper part of the lower pushing cylinder (4 - 12) is an outer - cone mating surface (4 - 12 - 1), and this outer - cone mating surface (4 - 12 - 1) is an upper inclined surface and can cooperate with the inner - cone mating surface (4 - 11 - 1) in the lower outer cylinder (4 - 11) of the flow - limiting device. At least one sealing - ring groove is machined in the outer - cone mating surface (4 - 12 - 1); the spring (4 - 13) of the flow - limiting device is installed in the inner cavity below the spring - limiting step (4 - 12 - 2) in the lower pushing cylinder (4 - 12).

18. A high - frequency injection - production pipe string for a compressed - air energy - storage vertical - inclined well as described in claim 17, characterized in that, the upper outer circle of the limiting cylinder (4 - 14) is provided with an external thread and can be thread - connected to the lower outer cylinder (4 - 11) of the flow - limiting device; the washing - aid and anti - spraying liquid - passing groove (4 - 14 - 1) arranged on the outer wall of the limiting cylinder (4 - 14) is a through - groove from top to bottom and at least one is provided; the upper outer cylinder (4 - 9) of the flow - limiting device is a non - equal - diameter cylindrical body, and the internal and external threads in the upper and lower ends of the cylinder body can be respectively thread - connected to the continuous thread (4 - 2 - 7) of the central tube (4 - 2) and the lower outer cylinder (4 - 11) of the flow - limiting device. After being connected to the central tube (4 - 2), the lower inner cavity of the upper outer cylinder (4 - 9) of the flow - limiting device is communicated with the limiting - plate installation groove (4 - 2 - 1).

19. A high - frequency injection - production pipe string for a compressed - air energy - storage vertical - inclined well as described in claim 18, characterized in that, in Centralizers (8) are connected in the straight and inclined well high-frequency injection and production string on both the upper and lower sides of the downhole annulus flow-limiting device (4), and flow nipples (7) are connected in the straight and inclined well high-frequency injection and production string on both the upper and lower sides of the downhole safety valve (6); the tubing includes small-diameter tubing (3) and large-diameter tubing (5), the centralizers (8) and the downhole annulus flow-limiting device (4) are connected in series in the small-diameter tubing (3), and the downhole safety valve (6) and the flow nipples (7) are connected in series in the large-diameter tubing (5).

20. A well completion method for a compressed air energy storage straight and inclined well high-frequency injection and production string according to any one of claims 1-19, characterized in that: it includes the following steps: A. Lower the preset working barrel (1) in the downhole combined sealing device into the well at a predetermined position in the well completion string for well completion; B. Connect the sealing working barrel (2) to the lower end of the injection and production string, lower it into the well, and press down the sealing working barrel (2) through the injection and production string to achieve the anchoring and sealing of the injection and production string and the well completion string; C. Pressurize the downhole annulus flow-limiting device (4) in the forward direction while testing whether the injection and production string leaks; D. If there is no leakage in the injection and production string during the pressure test, start the downhole annulus flow-limiting device (4); E. After starting the downhole annulus flow-limiting device (4), continue to pressurize for backwashing the well and verify whether the downhole combined sealing device works properly; F. After verifying that the downhole combined sealing device works properly, inject casing protection fluid; G. Reverse the well washing pipeline to the normal well washing process, wait for a period of time, and then apply ground pressure to break off the soluble plug in the downhole combined sealing device to complete the well completion of the straight and inclined well high-frequency injection and production string.

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