Compressed air energy storage horizontal well high-frequency injection-production pipe column and well completion method

Abstract

The invention relates to a compressed air energy storage horizontal well high-frequency injection and production pipe column and a well completion method, the injection and production pipe column 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 of the petroleum industry, and specifically to a high-frequency injection and production string for a compressed air energy storage horizontal well and a completion method therefor. Background Art

[0002] Underground gas storage has advantages such as safety and large storage capacity. At present, as long as the geological conditions are suitable, countries at home and abroad have widely adopted underground gas storage as an energy reserve. The construction of gas storage in China started relatively late. Therefore, there is still a large gap compared with developed countries in terms of quantity, storage capacity, or construction experience. Especially in the construction of compressed air energy storage type gas storage, since the stored energy is electric energy and compressed air is only a medium in the energy conversion process, when applying, the air needs to be converted into electric energy again through a turbine. Therefore, more stringent requirements are imposed on the displacement, anchoring, sealing, corrosion resistance, scale prevention, etc. of the injection and production string.

[0003] In the existing injection and production string in natural gas storage, due to the long injection and production cycle and low frequency, the gas-tight packer used in the string can still meet the injection and production requirements. For example, the following patented technologies: CN112647857B "Injection and Production String and Completion Method Using the Same" and CN206205797U "A Completion String for an Injection and Production Well in an Oil and Gas Reservoir Type Gas Storage" disclosed by the authorization announcement number both use a packer for anchoring and sealing.

[0004] However, if the above technologies are applied to the injection and production string of a compressed air gas storage, the packer therein cannot meet its injection and production requirements. The working state of the injection and production string of a compressed air gas storage under harsh working conditions is fully analyzed and described in articles such as "Research on the Dynamic Characteristics of Fluid-Induced Vibration and Buckling of the Injection and Production String in Gas Storage" and "Buckling Behavior of the Oil Pipe in Gas Storage under Multi-Cycle Injection and Production Conditions".

[0005] Most domestic gas storage sites are located in depleted oil and gas reservoir areas that have been exploited. Compared with salt cavern type gas storage or cavity type gas storage, the characteristics of the gas storage layer for storing gas are mostly small storage capacity, thin reservoir, large interlayer differences, serious sand production, strong geological inhomogeneity, and active edge and bottom water at the same time.

[0006] To meet the conditions of storage capacity, injection and production displacement, pressure, etc. in depleted oil and gas reservoir areas, the well type of injection and production wells should preferably adopt a horizontal well structure. However, most of the currently built compressed air gas storage sites are located in salt cavern type and adopt a vertical-inclined well structure. There is no mature and applicable horizontal well injection and production string for gas storage in China that can meet the working conditions. Therefore, there is an urgent need for a new type of injection and production string and supporting technology to solve the above problems. Summary of the Invention

[0007] To solve the above problems, the present invention provides a high-frequency injection-production string for a compressed air energy storage horizontal well and a completion method, mainly solving the problem that the injection-production strings used in existing salt cavern type and depleted gas storage reservoirs cannot meet the use requirements of the injection-production strings in the compressed air gas storage reservoir established in a depleted oil reservoir at present, and providing an injection-production string suitable for horizontal wells in a compressed air gas storage reservoir with a high injection-production frequency. The production efficiency of the compressed air gas storage reservoir is improved, and the injection-production benefit is improved.

[0008] The technical solution of the present invention is: a high-frequency injection-production string for a compressed air energy storage horizontal well, provided with a tubing string and a downhole safety valve, wherein: the injection-production string is successively connected with a downhole combined sealing device, a downhole annulus flow-limiting device and a downhole safety valve through the tubing string from bottom to top. 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 with the preset lower outer barrel, and the preset working barrel is pre-lowered into a preset horizontal section 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 buttress threads are machined on the outer circle of the limiting step three in the inner barrel; the sealing working barrel is connected to the lower end of the injection-production string and lowered into the preset working barrel, and the inner barrel is connected with 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 part sealing cavity of the preset lower outer barrel; the downhole annulus flow-limiting device is provided with a cup leather and a central pipe. The flow-limiting plate of the staggered converging flow channel is fixed in the flow-limiting plate installation groove in the wall of the central pipe, and a setting hole and a setting boosting hole are arranged in the wall without the 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 the locking ring groove on the outer circle of the central pipe; the upper pushing barrel is in buttress thread fit with the flow-limiting device locking ring installed in the locking ring installation groove of the central pipe.

[0009] 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.

[0010] Preferably, the top of the ring body of the pre-set locking ring is provided with a torque-transferring spline for the locking ring, the inner circle of the lower part of the pre-set locking ring is provided with a buttress thread, and the pre-set locking ring is an open ring with a straight or inclined through groove axially; the pre-set upper outer cylinder is a non-uniform-diameter cylinder, the inner cavity of the upper part of the pre-set upper outer cylinder 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 cylinder torque-transferring spline is provided on the inner circle of the locking ring limiting step; the upper outer cylinder torque-transferring spline can cooperate with the torque-transferring spline on the top of the ring body of the pre-set locking ring, and after cooperation, the pre-set locking ring is exactly located in the locking ring installation cavity between the locking ring limiting step and the lower threaded inner cavity.

[0011] Preferably, the pre-set lower outer cylinder is a non-uniform-diameter cylinder, the outer circles at both ends of the pre-set lower outer cylinder are 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 pre-set upper outer cylinder and the lower casing thread in the completion string; the upper inner cavity of the pre-set 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.

[0012] Preferably, the sealed insertion cylinder can be made of rubber or polymer material, soft metal or shape memory alloy, the lower outer circle of the sealed insertion cylinder is a conical outer circle, and the conical outer circle cooperates with the sealed insertion cylinder sealing cavity of the pre-set lower outer cylinder; a disc spring top ring is also installed between the disc spring and the sealed insertion cylinder.

[0013] 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, and the outer circles of the limiting steps one, two, three, four and five are all precision-machined outer circle surfaces.

[0014] 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 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, a buttress thread is machined on the 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.

[0015] Preferably, the middle locking ring is provided with a center hole and an inner circle is provided with a thread. After the middle locking ring is inserted into the outside of the inner tube, the inner thread of its inner circle is threadedly connected with the middle locking ring connecting thread; the sealing assembly is a combined seal, which includes at least one sealing ring and protective rings made of polytetrafluoroethylene respectively installed on both sides of the sealing ring, and the outer diameter of the sealing ring is larger than the inner diameter of the sealing cavity of the sealing member preset in the lower outer tube; the sealing pressure ring is connected with the spare component connecting thread at the lower part of the limiting step five, and a lower pressure ring and a soluble wire plug are also connected below the sealing pressure ring.

[0016] Preferably, the inner circle of the working cylinder slide is machined into two sections of inner diameter, which are smaller at the top and larger at the bottom, and the small inner diameter section is installed on the outside of the limiting step 1 of the inner cylinder, and the large inner diameter section is installed on the outside of the limiting step 2; the two sections of the inner diameter of the inner circle of the working cylinder slide are both finely machined surfaces; when the working cylinder slide is in normal working state, the small inner diameter section blocks the backwash hole, and the large inner diameter section is connected to the backwash control hole.

[0017] Preferably, the leather cup is installed in the flow limiting device slide cylinder and the lower part is located between the flow limiting device slide cylinder and the upper push cylinder, and seals are installed in the sealing surface of the outer circle of the center tube; the staggered converging flow channel is composed of a main channel groove processed in the center of the flow limiting plate and an auxiliary channel groove connected to the main channel groove; the limiting plate mounting groove and the flow limiting plate arranged on the outer wall of the center tube are arranged in more than one set, and the flow limiting plate is welded in the limiting plate mounting groove.

[0018] Preferably, the main channel groove is a straight groove that passes through 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 arc-shaped and sloping downward, and the auxiliary channel grooves arranged on both sides are staggered and connected end to end in the main channel groove.

[0019] Preferably, the locking ring and the current limiting device locking ring are both broken rings with axial cuts, the axial cuts 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 a natural state is smaller than the outer diameter of the central pipe section in which it is located; the outer circle of the current limiting device locking ring is machined with a tooth buckle and can cooperate with the inner circle of the upper push tube.

[0020] Preferably, the upper push cylinder is a non-uniform diameter cylindrical body, provided with an upper cylinder and a back-stop thread arranged in the lower cylinder, the inner diameter of the upper cylinder is smaller than the inner diameter of the lower cylinder, at least one auxiliary sealing liquid groove is arranged on the outer wall of the upper cylinder, and the auxiliary sealing liquid groove is connected with the top of the upper cylinder; the inner circle of the lower cylinder of the upper push cylinder is provided with a back-stop thread, and the back-stop thread is a horse tooth buckle type thread and can cooperate with the horse tooth buckle thread on the outer circle of the locking ring of the current limiting device.

[0021] Preferably, the outer circle of the central tube below the upper push cylinder limiting step is processed with a connecting thread, and the connecting thread can be threadedly connected to the washing auxiliary and anti-spraying mechanism through the connecting thread.

[0022] Preferably, the washing aid and anti-spray 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 spring of the flow-limiting device and a limiting cylinder. The two ends of the upper outer cylinder of the flow-limiting device are respectively threadedly connected to the continuous thread in the central tube and the lower outer cylinder of the flow-limiting device. The lower pushing cylinder and the spring of the flow-limiting device are installed in the lower outer cylinder of the flow-limiting device. The limiting cylinder is installed below the spring of the flow-limiting device and is threadedly connected to the lower outer cylinder of the flow-limiting device; at least one washing aid and anti-spray liquid passing groove is provided in the limiting cylinder.

[0023] Preferably, the inner circle of the lower outer cylinder of the flow-limiting device is a non-uniform diameter inner circle, and the inner threads at both ends are respectively threadedly connected to the upper outer cylinder of the flow-limiting device and the limiting cylinder; an inner conical mating surface is arranged between the two non-uniform diameter inner circles of the lower outer cylinder of the flow-limiting device, and this inner conical mating surface is a lower inclined surface.

[0024] Preferably, the lower pushing cylinder is a non-uniform diameter cylinder. The outer wall of the upper part of the lower pushing cylinder is an outer conical mating surface, and this outer conical mating surface is an upper inclined surface and can cooperate with the inner conical mating surface in the lower outer cylinder of the flow-limiting device. At least one sealing ring groove is machined in the outer conical mating surface; the spring of the flow-limiting device is installed in the inner cavity below the spring limiting step in the lower pushing cylinder.

[0025] 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 and anti-spray liquid passing groove arranged on the outer wall of the limiting cylinder is an up-and-down 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 respectively threadedly connected to the continuous thread of the central tube and the lower outer cylinder of the flow-limiting device. The lower inner cavity of the upper outer cylinder of the flow-limiting device after being connected to the central tube is communicated with the limiting plate installation groove.

[0026] Preferably, centralizers are connected in the straight-inclined well high-frequency injection-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-inclined well high-frequency injection-production pipe string on both the upper and lower sides of the downhole safety valve; the tubing includes small-diameter tubing, large-diameter tubing and small-diameter thickened tubing. The centralizer and the downhole annulus flow-limiting device are connected in series in the small-diameter tubing, the downhole safety valve and the flow nipple are connected in series in the large-diameter tubing, and a small-diameter thickened tubing and a downhole gas-solid separator are connected in series between the small-diameter tubing and the sealing working barrel.

[0027] Preferably, the downhole gas-solid separator is provided with an upper separator joint, an outer shell, a sand filtering cylinder, a swirl vane and a lower separator joint. The sand filtering cylinder with a centralizer and the swirl vane are respectively installed in the upper and lower parts of the outer shell. Between the upper end of the outer shell and the sand filtering cylinder, it is threadedly connected to the upper separator joint and a sealing ring is installed; at the lower part of the outer shell, it is threadedly connected to the lower separator joint and a sealing ring is installed to block the swirl vane in the outer shell.

[0028] Preferably, the upper inner cavity of the outer casing is larger than the lower inner cavity, and a conical transition cavity is provided in the middle of the inner cavity. Holes or grooves are provided in the barrel of the sand filtering cylinder. More than two centralizer pieces are provided at the lower end of the barrel of the sand filtering cylinder, and the outer diameter formed by the centralizer pieces is equal to or larger than the maximum inner diameter of the conical transition cavity in the outer casing. The swirl vane is a twisted plate structure, and the equivalent circle outer diameter, the pitch after twisting, and the thickness of the plate after twisting of the swirl vane match the spiral groove machined in the lower inner cavity of the outer casing.

[0029] The completion method for the injection-production string of a horizontal well for compressed air energy storage applied to the above-mentioned one includes the following steps: A. Connect the preset working barrel 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 barrel to the lower end of the injection-production string, lower it into the well, and press down the sealing working barrel through the injection-production string to realize the anchoring and sealing of the injection-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-production string leaks; D. If there is no leakage in the injection-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 to conduct reverse well flushing to verify whether the downhole combined sealing device works normally; F. After verifying that the downhole combined sealing device works normally, inject casing protection fluid; G. Reverse the well flushing pipeline to the normal well flushing process, wait for a period of time, and then apply surface pressure to break the soluble plug in the downhole combined sealing device to complete the completion of the injection-production string for vertical and inclined wells with high frequency.

[0030] Compared with the prior art, the present invention has the following advantages: (1) The injection-production string provided by the present invention adopts a downhole combined sealing device, in which the preset working barrel is pre-lowered into the preset horizontal section in the well together with the completion string, realizing efficient anchoring of the injection-production string, and solving the problem that the slips in the previous packer anchoring are prone to loosen and fail 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.

[0031] (2) The injection-production string provided by the present invention has a reverse well flushing function. After the normal injection-production cycle ends, the scale and wax in the oil pipe can be cleaned by reverse-circulating the well flushing fluid with a cleaning function, realizing maintenance without pulling the pipe 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.

[0032] (3) The inner barrel of the sealing working barrel in the present invention has a self reverse well flushing function, and it is easier to conduct well killing by reverse circulation during a blowout, effectively reducing the well killing difficulty during a blowout and improving the safety factor of the injection-production well in terms of process principle.

[0033] (4) Compared with the packers used in the existing pipe strings, the downhole combined sealing device in the present invention has a simple and reliable working principle. While improving the anchoring and sealing ability, it enhances the safety of the entire pipe string and tools. The provided reverse washing channel significantly reduces the probability of downhole accidents caused by scale blockage or wax build-up in the pipe string after the injection-production well is put into operation.

[0034] (5) The injection-production pipe string provided in the present invention realizes the requirement of blowout prevention for the oil-casing annulus while ensuring the smoothness of the reverse washing channel of the injection-production pipe string by adopting a downhole annulus flow-limiting device, improving the safety of the entire injection-production pipe string.

[0035] (6) Through the reverse washing channel, the present invention makes it possible to inject and replace the casing protection fluid infinitely, which can effectively prevent corrosion in the oil-casing annulus in the well, reduce the requirement for the material of the completion casing, and greatly save the completion cost.

[0036] (7) The completion method provided in the present invention can inspect the reliability of the injection-production pipe string in each step of the completion process, preventing the injection-production pipe string with potential hazards from entering the well.

[0037] In summary, while improving the safety of the entire pipe string, the present invention provides a reverse washing channel, significantly reducing the probability of downhole accidents caused by scale blockage in the tubing and the requirement for the casing material, extending the service life of the injection-production pipe 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

[0038] The 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 is the overall structural schematic diagram of the injection-production pipe string in the present invention.

[0039] Figure 2 is the structural schematic diagram of the preset working barrel in the present invention.

[0040] Figure 3 is Figure 2 the structural schematic diagram of the upper outer barrel.

[0041] Figure 4 is Figure 2 the structural schematic diagram of the locking ring in.

[0042] Figure 5 is the structural schematic diagram of the sealing working barrel in the present invention.

[0043] Figure 6 is Figure 5 the structural schematic diagram of the inner barrel in.

[0044] Figure 7 is Figure 1 Schematic structural diagram of the downhole casing - tubing annulus flow - limiting device.

[0045] Figure 8 is Figure 7 Schematic structural diagram of the central pipe.

[0046] Figure 9 is Figure 7 Schematic structural diagram of the upper push cylinder.

[0047] Figure 10 is Figure 7 Schematic structural diagram of the flow - limiting plate.

[0048] Figure 11 is Figure 7 Schematic structural diagram of the lower outer cylinder.

[0049] Figure 12 is Figure 7 Schematic structural diagram of the lower push cylinder.

[0050] Figure 13 is Figure 7 Schematic structural diagram of the limit cylinder.

[0051] Figure 14 is Figure 1 Schematic structural diagram of the downhole gas - solid separator.

[0052] Figure 15 is Figure 14 Schematic structural diagram of the swirl vane.

[0053] In the figure: pre - set working barrel 1, sealed working barrel 2, small - diameter tubing 3, downhole annulus flow - limiting device 4, large - diameter tubing 5, downhole safety valve 6, flow - through nipple 7, centralizer 8, small - diameter premium tubing 9, downhole gas - solid separator 10; Pre - set working barrel 1: pre - set upper outer barrel 1 - 1, upper outer barrel torque - transmitting spline 1 - 11; pre - set locking ring 1 - 2, locking ring torque - transmitting spline 1 - 21; pre - set lower outer barrel 1 - 3.

[0054] Sealed working barrel 2: inner barrel 2 - 1, back - washing hole 2 - 101, seal ring groove one 2 - 102, limit step one 2 - 103, back - washing control hole 2 - 104, seal ring groove two 2 - 105, limit step two 2 - 106, limit step three 2 - 107, limit step four 2 - 108, middle locking ring connection thread 2 - 109, limit step five 2 - 110; upper locking ring 2 - 2, working barrel sliding cylinder 2 - 3, working barrel spring 2 - 4, disc spring 2 - 5, disc spring top ring 2 - 6, sealing insert cylinder 2 - 7, middle locking ring 2 - 8, working barrel limit ring 2 - 9, sealing assembly 2 - 10, sealing pressure ring 2 - 11, lower pressure ring 2 - 12; Downhole annulus flow-limiting device 4, upper joint 4-1, central tube 4-2, limiter plate installation groove 4-2-1, setting hole 4-2-2, locking ring groove 4-2-3, setting boosting hole 4-2-4, locking ring installation groove 4-2-5, upper push cylinder limiting step 4-2-6, continuous thread 4-2-7, flow-limiting device sliding cylinder 4-3, locking ring 4-4, flow-limiting device limiting ring 4-5, cup leather 4-6, upper push cylinder 4-7, anti-back-off thread 4-7-1, upper cylinder body 4-7-2, assisting setting liquid-passing groove 4-7-3, flow-limiting device locking ring 4-8, flow-limiting device upper outer cylinder 4-9, flow-limiting plate 4-10, main channel groove 4-10-1, auxiliary channel groove 4-10-2, flow-limiting device lower outer cylinder 4-11, inner cone mating surface 4-11-1, lower push cylinder 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; Downhole gas-solid separator 10: separator upper joint 10-1, outer shell 10-2; sand filter cylinder 10-3, centering piece 10-3-1, swirl piece 10-4, separator lower joint 10-5. Specific embodiments

[0055] 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 with reference to 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.

[0056] 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 with reference to the attached drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0057] 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 attached drawings, and 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 cannot be understood 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.

[0058] See Figures 1 - 13, a high-frequency injection and production string for a compressed air energy storage horizontal well, which is provided with a tubing string 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 through the tubing string from bottom to top. 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. The preset working cylinder (1) is pre-lowered into the preset horizontal section 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. The outer circle of the limiting step three 2-107 in the inner cylinder 2-1 is processed 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 is matched with the buttress thread in the preset locking ring 1-2. The sealing insertion cylinder 2-7 seals the sealing insertion cylinder cavity of the preset lower outer cylinder 1-3, and the sealing assembly 2-10 seals the seal cavity 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. The flow-limiting plate 4-10 of the staggered converging flow channel is fixed in the 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 installed with a locking ring 4-4 is installed in the flow-limiting device sliding cylinder 4-3 above the cup leather 4-6. The locking ring 4-4 is installed in the locking ring groove 4-2-3 on the outer circle of the central tube 4-2. The upper pushing cylinder 4-7 is matched with a flow-limiting device locking ring 4-8 installed in the locking ring installation groove 4-2-5 of the central tube 4-2 through a buttress thread.

[0059] The downhole combined sealing device in the present invention is composed of two parts, namely a preset working cylinder 1 and a sealing working cylinder 2, and they are used in cooperation. The inner wall of the preset locking ring 1-2 in the preset working cylinder 1 is processed with a buttress thread, and the upper end is also processed with a locking ring torque transmission spline 1-21 matching the upper outer cylinder torque transmission spline 1-11 in the preset upper outer cylinder 1-1. The two are matched through splines to achieve the torque transmission function. The buttress thread on the inner wall of the preset locking ring 1-2 is also closely matched with the buttress thread in the inner cylinder 2-1 to achieve the axial one-way locking function.

[0060] According to the process requirements, when the leather cup 4-6 in the downhole annular flow limiting device 4 is sealed, when the liquid flows from the oil pipe through the sealing hole 4-2-2 into the gap between the flow limiting device slide 4-3 and the flow limiting device limit ring 4-5, the flow limiting device slide 4-3 is pushed up and the leather cup 4-6 is released from the flow limiting device slide 4-3; as the liquid enters through the sealing boost hole 4-2-4, the upper push cylinder 4-7 is moved up and the leather cup 4-6 is stuck in the oil casing annulus, so that the flow limiting device slide 4-3 and the casing are sealed. At this time, the backwashing operation can be carried out through the staggered collection flow channel in the flow limiting plate 4-10.

[0061] When the bottom hole pressure increases and a blowout occurs, the well fluid is blocked from flowing upward through the staggered convergence flow channels in the flow limiting plates 4-10 from below the device of the present invention, which effectively slows down the flow rate of the well fluid and weakens the intensity of the blowout, thus buying precious time for the emergency blowout work on the ground.

[0062] The flow limiting plate 4-10 in the device is provided with staggered converging flow channels and fixed in the flow limiting plate mounting groove 4-2-1 in the wall of the central tube 4-2. A seat seal hole 4-2-2 and a seat seal boost hole 4-2-4 are provided in the wall of the central tube 4-2 without the flow limiting plate mounting groove 4-2-1.

[0063] The leather cup 4-6 is installed in the flow limiting device slide 4-3 and the lower part is located between the flow limiting device slide 4-3 and the upper push tube 4-7. The flow limiting device limiting ring 4-5 installed with the locking ring 4-4 ​​is installed in the flow limiting device slide 4-3 above the leather cup 4-6; the locking ring 4-4 ​​installed in the locking ring groove 4-2-3 on the outer circle of the center tube 4-2 locks the flow limiting device limiting ring 4-5 at the inner top end of the flow limiting device slide 4-3 outside the center tube 4-2; the flow limiting device locking ring 4-8 is installed in the locking ring installation groove 4-2-5 of the center tube 4-2 and cooperates with the upper push tube 4-7 through a horse tooth buckle. 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 push tube 4-7 can move upward along the current limiting device locking ring 4-8, expand the leather cup 4-6, and then seal the annulus between the flow limiting device slide 4-3 and the casing.

[0064] The downhole annulus flow limiting device 4 can backwash the well while using the leather cup 4-6 to seal the oil casing annulus, and can throttle and limit the upwelling well fluid through the flow limiting plate 4-10. It is connected to the injection and production pipe string through the upper joint 4-1. This device has both the function of backwashing the well and the function of limiting and throttling the blowout.

[0065] The downhole annular flow limiting device 4 can buy time for controlling the blowout of the gas storage reservoir injection and production well when the downhole pipe string of the gas storage reservoir injection and production well blows out, add a safety guarantee, avoid the adverse consequences of the blowout, improve economic benefits, and have a significant use effect. The present invention can also be used in conventional oil production wells.

[0066] Based on the first embodiment above, the present invention further has the following embodiments: A preferred embodiment: The sealing working cylinder 2 is further provided with an upper locking ring 2-2, a working cylinder sliding cylinder 2-3, a working cylinder 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 cylinder sliding cylinder 2-3 and the working cylinder 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 cylinder 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 the sealing working cylinder 2 is connected to the preset working cylinder 1, below the third limiting step 2-107 which is tightly connected with the buttress thread, a disc spring 2-5 and a disc spring top ring 2-6 are further assembled. When the injection-production string is pressed down, due to the limitation of the preset working cylinder 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 cylinder 1 and the sealing working cylinder 2 from creeping within the range of one pitch. Below the sealing insertion cylinder 2-7, a middle locking ring 2-8 threadedly connected to the inner cylinder 2-1 is further provided to limit and tightly press the sealing insertion cylinder 2-7.

[0067] 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 buttress threads. The preset locking ring 1-2 is an open ring with a straight or inclined through groove axially opened; the preset upper outer cylinder 1-1 is a non-uniform diameter cylinder. The upper inner cavity of the preset upper outer cylinder 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 cylinder torque transmission spline 1-11 is provided on the inner circle of the locking ring limiting step; the upper outer cylinder 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. After 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.

[0068] A preferred embodiment: The preset lower outer cylinder 1-3 is a non-uniform diameter cylinder. The outer circles at both ends of the preset lower outer cylinder 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 cylinder 1-1 and the lower casing thread in the completion string; the upper inner cavity of the preset lower outer cylinder 1-3 is a sealing insertion cylinder sealing cavity, and the lower inner cavity is a seal sealing cavity; the sealing insertion cylinder sealing cavity is a conical cavity.

[0069] A preferred embodiment: The sealing insert cylinder 2-7 can be made of rubber or polymer materials, soft metals or shape memory alloys. The lower outer circle of the sealing insert cylinder 2-7 is a conical outer circle, which cooperates with the sealing insert 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 sealing insert 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 sealing insert cylinder 2-7, and during operation, the disc spring top ring 2-6 can provide a locking and tightening force to prevent loosening of the knuckle thread, improving and strengthening the tightening effect of the disc spring 2-5 on the sealing insert cylinder 2-7, and further improving the sealing effect.

[0070] A preferred embodiment: The inner cylinder 2-1 is a non-uniform diameter cylinder. Injection and 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. Limiting steps one 2-103, two 2-106, three 2-107, four 2-108 and five 2-110 are successively arranged on the outer circle of the inner cylinder 2-1 from top to bottom. The outer circles of the limiting steps one 2-103, two 2-106, three 2-107, four 2-108 and five 2-110 are all precision-machined outer circle surfaces.

[0071] 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 and production pipe string connection thread, and sealing ring grooves one are arranged on the upper and lower sides of the backwashing hole 2-101 and sealing rings are installed; 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 a knuckle 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 limiting step four 2-108; a spare part connection thread is machined at the lower part of the limiting step five 2-110.

[0072] 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 thread 2-109 of the middle locking ring to provide 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 larger 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 thread of the spare part 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 pressing and locking forces for the sealing assembly 2-10 and the sealing pressure ring 2-11 and prevents the sealing pressure ring 2-11 from loosening.

[0073] Preferred embodiment: 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 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. When the working cylinder sliding cylinder 2-3 is in the normal working state, 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 the 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 drains 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, sealing the oil-casing communication channel.

[0074] 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.

[0075] 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.

[0076] After the sealing working barrel 2 is inserted into the preset working barrel 1, the sealing insertion 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 oil-casing annulus. At the same time, the screw 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 insertion barrel 2-7. The disc spring 2-5 compresses and stores a certain tonnage of pressure to prevent the screw threads from creeping within the range of one pitch.

[0077] 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 screw threads between 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 reverse circulation well flushing, pumping casing protection fluid or encountering downhole overflow accidents are required for the injection-production string, the well flushing fluid or kill fluid can be pumped into the oil-casing annulus to provide a process channel for the cleaning or kill operation of the injection-production string.

[0078] A preferred embodiment: See Figure 7 、 Figure 8 and Figure 10 , the leather cup 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 push barrel 4-7. Sealing elements 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 connected to the main channel groove 4-10-1; the limiting plate installation 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 installation grooves 4-2-1.

[0079] A preferred embodiment: The main channel groove 4-10-1 is a straight groove that directly leads 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. The auxiliary channel grooves 4-10-2 arranged on both sides are staggered and 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.

[0080] Preferred embodiment: The locking ring 4-4 and the locking ring 4-8 of the flow-limiting device are both 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 locking 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 locking 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 in the locking ring groove 4-2-3. The outer circle of the locking ring 4-8 of the flow-limiting device 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.

[0081] Preferred embodiment: The upper push cylinder 4-7 is a non-uniform diameter cylinder, provided with an upper cylinder 4-7-2 and a backstop thread 4-7-1 arranged in the lower cylinder. The inner diameter of the upper cylinder 4-7-2 is smaller than that of the lower cylinder. At least one liquid-assisted sealing and passing groove 4-7-3 is arranged on the outer wall of the upper cylinder 4-7-2, and the liquid-assisted sealing and passing groove 4-7-3 communicates with the top of the upper cylinder 4-7-2. The inner circle of the lower cylinder of the upper push cylinder 4-7 is provided with a backstop thread 4-7-1. The backstop thread 4-7-1 is a buttress thread type and can cooperate with the buttress thread on the outer circle of the locking ring 4-8 of the flow-limiting device.

[0082] Preferred embodiment: The outer circle of the central tube 4-2 below the upper push cylinder limiting 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.

[0083] Preferred embodiment: Refer to Figure 12 , the washing and blowout prevention 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 push cylinder 4-12, a flow-limiting device spring 4-13 and a limiting cylinder 4-14. The two ends of the upper outer cylinder 4-9 of the flow-limiting device are respectively threadedly connected with the connecting thread 4-2-7 in the central tube 4-2 and the lower outer cylinder 4-11 of the flow-limiting device. The lower push cylinder 4-12 and the flow-limiting device spring 4-13 are installed in the lower outer cylinder 4-11 of the flow-limiting device. The limiting cylinder 4-14 is installed below the flow-limiting device spring 4-13 and is threadedly connected with the lower outer cylinder 4-11 of the flow-limiting device. At least one liquid-assisted washing and blowout prevention passing groove 4-14-1 is arranged in the limiting cylinder 4-14. This enables the incoming water and liquid from below the annulus flow-limiting device not to enter above the annulus flow-limiting device through the lower push cylinder 4-12, and the incoming water and liquid 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.

[0084] 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 inner 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 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.

[0085] A preferred embodiment: Refer to Figure 12 , the lower push cylinder 4-12 is a non-uniform-diameter cylinder, the outer wall of the upper part 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.

[0086] 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 cylinder, and the internal and external threads in the cylinders at the upper and lower ends 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 annular flow-limiting device, sealing elements are provided in the sealing mating surfaces between components.

[0087] 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 limiting the spray 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.

[0088] When the downhole pressure increases and a blowout occurs, due to the sealing of the leather cup 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 upward flow rate and pressure are greatly reduced, buying more time for the ground staff to prevent blowout.

[0089] 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, large-diameter tubing 5, and small-diameter thickened tubing 9. The centralizer 8 and the downhole annulus flow-limiting device 4 are connected in series in the small-diameter tubing 3, the downhole safety valve 6 and the flow nipple 7 are connected in series in the large-diameter tubing 5, and the small-diameter thickened tubing 9 and the downhole gas-solid separator 10 are connected in series between the small-diameter tubing 3 and the sealing working barrel 2. The tubing includes small-diameter tubing 3, large-diameter tubing 5, and small-diameter thickened tubing 9. 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 in 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. Three types of tubing are provided. The small-diameter thickened tubing 9 is connected in the injection-production string in the inclined section of the wellbore, the small-diameter tubing 3 is connected in the middle of the string, and the large-diameter tubing 5 is connected in 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.

[0090] A preferred embodiment: The downhole gas-solid separator 10 is provided with a separator upper joint 10-1, an outer casing 10-2, a sand filter cylinder 10-3, a swirl vane 10-4, and a separator lower joint 10-5. The sand filter cylinder 10-3 with a centralizing piece 10-3-1 and the swirl vane 10-4 are respectively installed in the upper and lower parts of the outer casing 10-2. A sealing ring is threadedly connected and installed between the upper end of the outer casing 10-2 and the sand filter cylinder 10-3 and the separator upper joint 10-1; a sealing ring is threadedly connected and installed between the lower part of the outer casing 10-2 and the separator lower joint 10-5 to block the swirl vane 10-4 in the outer casing 10-2.

[0091] A preferred embodiment: The upper inner cavity of the outer casing 10-2 is larger than the lower inner cavity, and a conical transition cavity is provided in the middle of the inner cavity. The barrel of the sand filter cylinder 10-3 is provided with holes or grooves. More than two centralizing pieces 10-3-1 are provided and are arranged at the lower end of the barrel of the sand filter cylinder 10-3. The outer diameter formed by the centralizing pieces 10-3-1 is equal to or larger than the maximum inner diameter of the conical transition cavity in the outer casing 10-2. The sand filter cylinder 10-3 is of a cylindrical structure, and the upper end is processed with threads to be connected to the separator upper joint 10-1. In the present invention, the sand filter cylinder 10-3 adopts a slotted screen pipe, but is not limited to the slotted screen pipe, and may also be a screen cloth type or a pre-packed sand filter structure; the swirl vane 10-4 is a twisted plate structure, and the equivalent circular outer diameter, the pitch after twisting, and the thickness of the plate after twisting of the swirl vane 10-4 are matched with the spiral groove processed in the lower inner cavity of the outer casing 10-2.

[0092] The working principle of the downhole gas-solid separator 10 is that when the fluid is produced, it passes through the swirl vanes 10-4 at high speed, causing the fluid to rotate at high speed while advancing. Due to the different densities of gas and solid, under the action of centrifugal force, the tiny sand grains in the airflow are thrown to the periphery and enter the sand storage cavity of the outer housing 10-2, thereby reducing the erosion of the inner wall of the tubing by the high-speed airflow in the build section.

[0093] The completion method applied to the injection-production string for high-frequency injection and production in a compressed air energy storage horizontal well includes the following steps: A. Connect the preset working barrel 1 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 barrel 2 to the lower end of the injection-production string, lower it into the well, and press down the sealing working barrel 2 through the injection-production string to achieve the anchoring and sealing of the injection-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-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 is tested without leakage during the pressure test, start the downhole annulus flow-limiting device 4; during this process, connect the casing valve pipeline to pressurize through the oil-casing annulus and 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 a returned fluid 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 and pressurize. If the pressure does not drop when it reaches the predetermined value, it proves that the backwashing channel in the downhole combined sealing device automatically closes 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 oil-casing annulus; G. Reverse the well-washing pipeline to the normal well-washing process, wait for a period of time, and then pressurize on the ground to break the soluble plug in the downhole combined sealing device to complete the completion of the injection-production string for high-frequency injection and production in the vertical and inclined wells. If there are abnormal situations in the above technological steps, the injection-production string needs to be pulled out by rotating clockwise and replaced.

[0094] The working principle of the injection-production string is that after the normal injection-production cycle ends, use the liquid for removing scale, rust, and wax to clean the inside of the injection-production string through the backwashing method to prevent a large amount of scale generated due to the high intensity and frequency of injection-production air from blocking the channels of the injection-production string. At the same time, replace the annulus casing protection fluid, thereby reducing the cost and time of replacing the injection-production string, extending the service life of the injection-production string, and improving the use efficiency of the gas storage reservoir.

[0095] The embodiments described above are only typical embodiments, but the present invention is not limited to these embodiments. 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 for 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 above description.

Claims

1. A high-frequency injection-production string for a compressed air energy storage horizontal well, which is provided with a tubing string and a downhole safety valve (6). Its characteristics are as follows: The injection-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 string. The downhole combined sealing device is formed by inserting a preset working barrel (1) and a sealing working barrel (2). In the preset working barrel (1), a preset locking ring (1-2) with a buttress thread is installed between a preset upper outer barrel (1-1) and a preset lower outer barrel (1-3). The preset upper outer barrel (1-1) is connected to the preset lower outer barrel (1-3). The preset working barrel (1) is pre-lowered into a preset horizontal section 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 limiting 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-production string and lowered into the preset working barrel (1). The inner barrel (2-1) is connected to the buttress thread in the preset locking ring (1-2). The sealing insertion barrel (2-7) seals the sealing insertion barrel sealing cavity of the preset lower outer barrel (1-3), and the sealing assembly (2-10) seals the seal sealing cavity of the preset lower outer barrel (1-3). The downhole annulus flow-limiting device (4) is provided with a cup (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 pushing barrel limiting step (4-2-6) of the central pipe (4-2), a flow-limiting device sliding barrel (4-3), a cup (4-6) and an upper pushing barrel (4-7) are successively installed from top to bottom. A flow-limiting device limiting ring (4-5) installed with a locking ring (4-4) is installed in the flow-limiting device sliding barrel (4-3) above the cup (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 pushing barrel (4-7) is in buttress thread fit 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).

2. A high-frequency injection-production string for a compressed air energy storage horizontal well according to claim 1, Its characteristics are as follows: 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 inserting 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 horizontal 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 with a straight or inclined through groove axially opened; 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 horizontal 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 inserting barrel sealing cavity, and the lower inner cavity is a seal sealing cavity; the sealing inserting barrel sealing cavity is a conical cavity.

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

6. The high-frequency injection-production string for a compressed air energy storage horizontal well according to claim 5, characterized in that The inner cylinder (2-1) is a non-uniform diameter cylindrical body, 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); 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 string for a compressed air energy storage horizontal well according to 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 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 locking 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 string for a compressed air energy storage horizontal well according to claim 7, characterized in that the middle locking ring (2-8) is provided with a central hole and an internal thread on its inner circle. After the middle locking ring (2-8) is sleeved outside the inner cylinder (2-1), the internal thread on its inner circle is threadedly connected with the middle locking ring connection thread (2-109); 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 larger than the inner diameter of the seal cavity of the seal in the preset lower outer cylinder (1-3); the sealing pressing 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 pressing ring (2-12) and a soluble plug are also connected below the sealing pressing ring (2-11).

9. A high-frequency injection-production string for a compressed air energy storage horizontal well according to 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 blocks the backwashing hole (2-101), and the larger inner diameter section is communicated with the backwashing control hole (2-104).

10. A high-frequency injection and production string for a compressed air energy storage horizontal well according to claim 1, characterized in that, the cup packer (4-6) is installed inside the flow-limiting device sliding cylinder (4-3) and its 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 high-frequency injection and production string for a compressed air energy storage horizontal well 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 high-frequency injection and production string for a compressed air energy storage horizontal well 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 corresponding section of the central pipe (4-2); 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 high-frequency injection and production string for a compressed air energy storage horizontal well 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 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, and 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 backstop thread (4-7-1), and the backstop 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 high-frequency injection and production string for a compressed air energy storage horizontal well according to claim 13, characterized in that, a continuation 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 through this continuation thread (4-2-7), it can be threadedly connected with the washing and blowout prevention mechanism.

15. A high-frequency injection and production string for a compressed air energy storage horizontal well 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 string for a compressed - air energy - storage horizontal well according to 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 conical mating surface (4 - 11 - 1) is provided between the two non - equal - diameter inner circles of the lower outer cylinder (4 - 11) of the flow - limiting device, and the inner conical mating surface (4 - 11 - 1) is a lower inclined surface.

17. A high - frequency injection - production string for a compressed - air energy - storage horizontal well according to 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 conical mating surface (4 - 12 - 1), and the 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. At least one sealing - ring groove is machined in the outer conical 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 string for a compressed - air energy - storage horizontal well according to 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) provided in the outer wall of the limiting cylinder (4 - 14) is a through - hole in the up - and - down direction 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 string for a compressed - air energy - storage horizontal well according to claim 18, characterized in that, in The centralizer (8) is connected in the vertical 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 the flow short joint (7) is connected in the vertical 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), large-diameter tubing (5), and small-diameter thickened tubing (9). 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 short joint (7) are connected in series in the large-diameter tubing (5). The small-diameter thickened tubing (9) and the downhole gas-solid separator (10) are connected in series between the small-diameter tubing 3 and the seal working barrel (2).

20. A high-frequency injection and production string for a compressed air energy storage horizontal well as described in claim 19, characterized in that, the downhole gas-solid separator (10) is provided with a separator upper joint (10-1), an outer casing (10-2), a sand filter cylinder (10-3), a swirl vane (10-4), and a separator lower joint (10-5). The sand filter cylinder (10-3) with a centralizing piece (10-3-1) and the swirl vane (10-4) are respectively installed in the upper and lower parts of the outer casing (10-2). A sealing ring is threadedly connected and installed between the upper end of the outer casing (10-2) and the sand filter cylinder (10-3) with the separator upper joint (10-1); a sealing ring is threadedly connected and installed between the lower part of the outer casing (10-2) and the separator lower joint (10-5), and the swirl vane (10-4) is blocked inside the outer casing (10-2).

21. A high-frequency injection and production string for a compressed air energy storage horizontal well as described in claim 20, characterized in that, the upper inner cavity of the outer casing (10-2) is larger than the lower inner cavity, and a conical transition cavity is provided in the middle of the inner cavity. The barrel of the sand filter cylinder (10-3) is provided with holes or grooves. Two or more centralizing pieces (10-3-1) are provided and arranged at the lower end of the barrel of the sand filter cylinder (10-3). The outer diameter formed by the centralizing pieces (10-3-1) is equal to or larger than the maximum inner diameter of the conical transition cavity in the outer casing (10-2); the swirl vane (10-4) is a twisted plate structure, and the equivalent circular outer diameter, pitch, and thickness of the plate after twisting are matched with the spiral groove processed in the lower inner cavity of the outer casing (10-2).

22. A well completion method for a high-frequency injection and production string for a compressed air energy storage horizontal well as described in any one of claims 1-21, 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 seal working barrel (2) to the lower end of the injection and production string and lower it into the well. Press down the seal working barrel (2) through the injection and production string to achieve 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 positive direction, 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 (4); E. After starting the downhole annulus flow-limiting device (4), continue to apply pressure for backwashing the well to verify whether the downhole combined sealing device is working properly; F. After verifying that the downhole combined sealing device is working properly, inject casing protection fluid; G. Reverse the well-washing pipeline to the normal well-washing process. After standing for a period of time, apply surface pressure to remove the soluble plug in the downhole combined sealing device, thus completing the completion of the straight-inclined well high-frequency injection-production string.

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