Glass fiber reinforced plastic gas injection and brine discharge process pipe column and method for salt-cavern gas storage

Abstract

The invention provides a salt-cavern gas storage glass fiber reinforced plastic gas injection and brine discharge process pipe column and method. The pipe column comprises a brine discharge outer pipe which is coaxially arranged in a production sleeve; the brine discharging inner pipe is arranged inside the brine discharging outer pipe, and the lower end of the brine discharging inner pipe extends to the lower part of the salt cavern; wherein a plurality of hydraulic impeller rotators are arranged on the brine discharging inner pipe, and brine flowing in the brine discharging inner pipe drives the hydraulic impeller rotators to rotate so as to cut salt crystals. The method comprises the following steps: assembling and installing the glass fiber reinforced plastic gas injection and brine discharge process pipe column of the salt cavern gas storage; gas is injected into the brine discharging outer pipe, and brine in the salt cavern is discharged through the brine discharging inner pipe under the pressure action of the gas. Gas injection and brine discharge can be realized, and a salt cavern is changed into a gas storage.

Description

Technical Field

[0001] The present invention relates to a glass fiber reinforced plastic gas injection and brine drainage process string and method for a salt cavern gas storage, belonging to the technical field of salt cavern oil storage construction engineering. Background Art

[0002] Salt cavern gas storage is one of the main types of gas storage at home and abroad, accounting for about 10% of the total. Single-well single-cavity solution mining is the main cavity-forming method at home and abroad. After cavity formation, gas injection and brine drainage operations are carried out to discharge the brine in the cavity and achieve the purpose of gas storage. The pipe string material used for gas injection and brine drainage is generally made of N80 and P110 steel. During the implementation of gas injection and brine drainage, due to the changes in pressure and temperature, salt crystallization occurs inside the brine drainage pipe string, affecting the discharge rate. Seriously, it may cause pipe string blockage and accidents. In on-site construction, freshwater flushing is generally used to prevent and solve the problem of salt crystallization blocking the pipe string. Due to frequent flushing operations, it seriously affects the construction progress of gas injection and brine drainage, increases costs, and greatly prolongs the construction period of the gas storage.

[0003] The present invention uses a glass fiber reinforced plastic gas injection and brine drainage inner pipe string and connects a multi-stage hydraulic rotary impeller downhole tool, which greatly delays the salt crystallization speed, reduces the frequency of well flushing, reduces operation costs, improves the efficiency of gas injection and brine drainage, and speeds up the construction progress of the gas storage. Summary of the Invention

[0004] In view of the above technical problems existing in the prior art, the present invention proposes a glass fiber reinforced plastic gas injection and brine drainage process string and method for a salt cavern gas storage, which can inject gas and drain brine to convert the salt cavern into a gas storage.

[0005] On the other hand, the present invention uses a glass fiber reinforced plastic gas injection and brine drainage inner pipe string to improve the inner wall smoothness, and connects a multi-stage hydraulic rotary impeller downhole tool to increase the agitation of the brine fluid. These technical measures greatly delay the salt crystallization speed, reduce the frequency of well flushing, reduce operation costs, improve the efficiency of gas injection and brine drainage, and speed up the construction progress of the gas storage.

[0006] The present invention proposes a glass fiber reinforced plastic gas injection and brine drainage process string for a salt cavern gas storage, including:

[0007] A brine drainage outer pipe, which is coaxially arranged inside the production casing; and

[0008] A brine drainage inner pipe arranged inside the brine drainage outer pipe, the lower end of the brine drainage inner pipe extending to the lower part of the salt cavern;

[0009] Wherein, a plurality of hydraulic impeller rotators are arranged on the brine drainage inner pipe, and the brine flowing in the brine drainage inner pipe drives the water wheel rotator to rotate so as to cut the salt crystals.

[0010] A further improvement of the present invention lies in that the outer brine discharge pipe is made of steel material, and the inner brine discharge pipe is made of fiberglass; the hydraulic impeller rotator is made of fiberglass or stainless steel.

[0011] A further improvement of the present invention lies in that the hydraulic impeller rotator is arranged at a position where salt is likely to precipitate and crystallize.

[0012] A further improvement of the present invention lies in that the hydraulic impeller rotator includes a tool outer pipe, and a rotating impeller device is arranged inside the tool outer pipe. The rotating impeller device rotates with the flow of brine and simultaneously cuts salt crystals.

[0013] A further improvement of the present invention lies in that the upper part inside the tool outer pipe is connected to an upper retaining ring through an upper fixing rib, and the lower part is connected to a lower retaining ring through a lower fixing rib. The rotating impeller device is rotatably connected between the upper retaining ring and the lower retaining ring.

[0014] A further improvement of the present invention lies in that the rotating impeller device includes a core shaft rotatably connected to the upper retaining ring and the lower retaining ring. A rotating ring is arranged outside the core shaft, and a plurality of rotating impellers are arranged on the outer wall of the rotating ring. Blades are arranged outside the rotating impellers.

[0015] A further improvement of the present invention lies in that the number of the blades is four and they are evenly arranged in the circumferential direction of the core shaft; the number of the upper fixing ribs is two and they are arranged on both sides of the upper retaining ring at 180 degrees, and the number of the lower fixing ribs is two and they are arranged on both sides of the lower retaining ring at 180 degrees.

[0016] A further improvement of the present invention lies in that a packer is arranged at the lower part of the outer brine discharge pipe to seal the annulus between the outer brine discharge pipe and the production casing.

[0017] According to another aspect of the present invention, there is also a method for injecting gas and discharging brine in a salt cavern gas storage with fiberglass, which is realized by using the salt cavern gas storage fiberglass injection gas and brine discharge process string, and it includes:

[0018] Assemble and install the salt cavern gas storage fiberglass injection gas and brine discharge process string;

[0019] Inject gas into the outer brine discharge pipe. Under the pressure of the gas, the brine in the salt cavern is discharged through the inner brine discharge pipe.

[0020] A further improvement of the present invention lies in that when the brine flows in the inner brine discharge pipe, it drives the hydraulic impeller rotator to rotate, and the blades of the hydraulic impeller rotator scrape out salt crystals.

[0021] Compared with the prior art, the advantages of the present invention are:

[0022] The glass fiber reinforced plastic (FRP) gas injection and brine drainage process string and method for salt cavern gas storage in the present invention can inject gas and drain brine, converting the salt cavern into a gas storage. By using an FRP inner string for gas injection and brine drainage in the present invention, the inner wall smoothness is improved, and a multi-stage hydraulic rotary impeller downhole tool is connected to increase the agitation of the brine fluid. These technical measures greatly delay the salt crystallization rate, reduce the frequency of well flushing, lower the operation cost, improve the gas injection and brine drainage efficiency, and accelerate the construction progress of the gas storage.

[0023] In the FRP gas injection and brine drainage process string for salt cavern gas storage in the present invention, the annulus between the outer brine drainage pipe and the inner brine drainage pipe serves as the gas injection channel, and the internal channel of the inner brine drainage pipe serves as the brine drainage channel. Since the outer brine drainage pipe is arranged at the upper part of the salt cavern, the injected gas is injected into the upper part of the salt cavern from the wellhead through the gas injection channel. The gas in the upper part of the salt cavern increases and the pressure becomes larger, pushing the brine in the lower part of the salt cavern to flow upward through the brine drainage channel until it is discharged; the hydraulic impeller rotator can rotate when the brine flows, and at the same time, the rotation of the impeller can cut the inside of the pipe, thereby scraping off the salt crystals precipitated from the brine.

[0024] In the FRP gas injection and brine drainage process string for salt cavern gas storage in the present invention, by using an FRP inner string for gas injection and brine drainage, the inner wall smoothness is greatly improved, the degree of salt crystallization on the inner pipe surface and the hydraulic loss are reduced, and the brine drainage rate and system efficiency are improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The preferred embodiments of the present invention will be described in detail below with reference to the drawings. In the drawings:

[0026] Figure 1 Shows a schematic structural diagram of an FRP gas injection and brine drainage process string for salt cavern gas storage according to an embodiment of the present invention;

[0027] Figure 2 Shows a schematic structural diagram of a hydraulic impeller rotator according to an embodiment of the present invention, showing the structure of a side half-section view;

[0028] Figure 3 Shows a schematic structural diagram of a hydraulic impeller rotator according to an embodiment of the present invention, showing the side view structure in the axial direction.

[0029] The drawings are not drawn to actual scale.

[0030] The meanings of the reference numerals in the drawings are as follows:

[0031] 1. Production casing, 2. Packer, 3. Hydraulic impeller rotator, 4. Outer brine discharge pipe, 5. Gas injection and brine discharge water flow direction, 6. Inner gas injection and brine discharge pipe, 7. Bottom sediment of insoluble matter, 101. Outer tool pipe, 201. Upper fixing rib, 301. Rotating impeller, 302. Blade, 303. Swivel ring, 401. Lower fixing rib, 501. Lower retaining ring, 601. Mandrel, 701. Upper retaining ring. Detailed implementation mode

[0032] In order to make the technical solutions and advantages of the present invention clearer and more understandable, the exemplary embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than an exhaustive list of all embodiments. And without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0033] Figure 1 Schematically shows a fiberglass gas injection and brine discharge process string for a salt cavern gas storage, which can inject gas and discharge brine to convert the salt cavern into a gas storage.

[0034] In this embodiment, the fiberglass gas injection and brine discharge process string for a salt cavern gas storage includes: an outer brine discharge pipe 4, which is of a cylindrical structure and extends from the wellhead into the wellbore, and the lower end extends to the upper part of the salt cavern. In this embodiment, the outer brine discharge pipe 4 is sleeved inside the production casing 1 and is coaxially arranged with the production casing 1. The lower end seals the annulus between the production casing 1 and the outer brine discharge pipe 4 through a packer 2, and the packer 2 can be used to support the lower end of the outer brine discharge pipe 4.

[0035] An inner brine discharge pipe 6 is arranged inside the outer brine discharge pipe 4, and the inner brine discharge pipe 6 is coaxially arranged with the outer brine discharge pipe 4. In this embodiment, the lower section of the inner brine discharge pipe 6 extends beyond the outer brine discharge pipe 4 and extends to the lower part of the salt cavern.

[0036] In this way, the annulus between the outer brine discharge pipe 4 and the inner brine discharge pipe 6 serves as the gas injection channel, and the internal channel of the inner brine discharge pipe 6 serves as the brine discharge channel. Since the outer brine discharge pipe 4 is arranged at the upper part of the salt cavern, the injected gas is injected into the upper part of the salt cavern through the gas injection channel. The gas in the upper part of the salt cavern increases and the pressure becomes larger, pushing the brine in the lower part of the salt cavern to flow upward through the brine discharge channel until it is discharged.

[0037] In this embodiment, several hydraulic impeller rotators 3 are arranged on the inner brine discharge pipe 6. The hydraulic impeller rotators 3 can rotate when the brine flows, and at the same time, the rotation of the impeller can cut the inside of the pipe, so as to scrape off the salt crystals precipitated from the brine.

[0038] Preferably, the water wheel rotator is a short cylindrical section, connected in the brine discharge inner pipe 6, and connected to the brine discharge inner pipe 6 at both ends. The brine discharge inner pipe 6 is divided into multiple sections, and two sections are connected by a water wheel rotator. The outer wall of the water wheel rotator is hermetically connected to the brine discharge inner pipe 6, and a water wheel is arranged inside, which can rotate driven by the flow of brine, and the blade 302 can cut salt crystals.

[0039] In one embodiment, the brine discharge outer pipe 4 is made of steel material, and the brine discharge inner pipe 6 is made of fiberglass; the hydraulic impeller rotator 3 is made of fiberglass or stainless steel.

[0040] In the fiberglass gas injection and brine discharge process string of the salt cavern gas storage according to this embodiment, by using the fiberglass gas injection and brine discharge inner pipe 6 string, the inner wall finish is greatly improved, the degree of salt crystallization on the inner pipe surface and the hydraulic loss are reduced, and the brine discharge rate and system efficiency are improved.

[0041] Connecting multiple hydraulic impeller rotators 3 increases the agitation of the brine fluid, increases the intensity of the brine fluid turbulence and the crushing of salt crystal nuclei, and greatly delays the purpose of salt crystallization inside the brine discharge pipe string. This patent measure greatly delays the salt crystallization speed, reduces the frequency of well flushing, reduces the operation cost, improves the gas injection and brine discharge efficiency, and speeds up the construction progress of the gas storage.

[0042] In one embodiment, the hydraulic impeller rotator 3 is arranged at the position where salt is likely to precipitate crystals. The position where salt is likely to precipitate crystals in the well is obtained based on experience, or determined by indoor experiments and / or computer numerical simulation methods.

[0043] The hydraulic impeller rotator 3 is arranged at the position where salt is likely to precipitate crystals in the well. There is no need to set too many hydraulic impeller rotators 3, only need to set it at the key positions, which can reduce the number of hydraulic impeller rotators 3, save costs, and will not affect the flow velocity of the fluid and the rotation speed of the hydraulic impeller rotator.

[0044] In one embodiment, as Figure 2 shown, the hydraulic impeller includes a tool outer pipe 101 connected to the brine discharge inner pipe 6. The tool outer pipe 101 is a cylindrical structure, and a rotating impeller device is arranged inside it. The rotating impeller device rotates when the brine flows, and at the same time, the rotating impeller device cuts the salt crystals.

[0045] Two retaining rings are arranged inside the tool outer pipe 101, namely an upper retaining ring 701 and a lower retaining ring 501. The upper retaining ring 701 and the lower retaining ring 501 are arranged at both ends of the rotating impeller device and are rotatably connected. The retaining rings are cylindrical structures and are connected to the tool outer pipe 101 through fixing ribs. Among them, the upper retaining ring 701 is connected to the tool outer pipe 101 through an upper fixing rib 201, and the lower retaining ring 501 is connected to the tool outer pipe 101 through a lower fixing rib 401.

[0046] In the glass fiber reinforced plastic gas injection and brine drainage process string for salt cavern gas storage according to this embodiment, the retaining ring has a cylindrical structure, and an annular groove is provided inside it for installing the rotating impeller device. The groove is a groove of a stepped device, and the end is provided with an opening. The rotating impeller device is inserted at the position of the opening of the groove, and the rotating impeller device can rotate relatively within the groove of the retaining ring, or the rotating impeller device is fixedly connected within the groove and can itself rotate, both of which can be achieved. The upper retaining ring 701 and the lower retaining ring 501 define the position of the rotating impeller device to prevent it from falling off.

[0047] In one embodiment, the rotating impeller device includes a core shaft 601 rotatably connecting the upper retaining ring 701 and the lower retaining ring 501. A rotating ring 303 is provided outside the core shaft 601, and a plurality of rotating impellers 301 are provided on the outer wall of the rotating ring 303. Blades 302 are provided outside the rotating impellers 301.

[0048] Among them, the core shaft 601 has a circular tubular structure, and its upper and lower ends are both inserted into the groove of the retaining ring. The rotating ring 303 is sleeved on the core shaft 601 and can rotate on the core shaft 601. The rotating impellers are provided on the rotating ring 303 and rotate with the rotation of the rotating ring 303. The blades 302 are fixed on the rotating impellers and are inclined. During the flow of the brine, the axial force of the brine is converted into a circumferential force, thereby driving the rotating ring 303 to rotate around the core shaft 601.

[0049] In the glass fiber reinforced plastic gas injection and brine drainage process string for salt cavern gas storage according to this embodiment, the blades 302 are inclined and can be pushed to rotate when the brine flows through. During the flow of the brine, the salt in it will crystallize on the inner wall of the brine drainage inner pipe 6 to form salt crystals. When the blades 302 rotate, the blades 302 can cut the salt crystals, thereby scraping off the salt crystals.

[0050] In the implementation as Figure 3 shown, there are four blades 302 in the rotating impeller device, which are evenly arranged in the circumferential direction of the core shaft 601, and the included angle between two adjacent blades 302 is 90 degrees. The blades 302 can be at the same position or at different positions in the axial direction of the rotating impeller device. When set at the same position, the cutting ability is increased, and when set at different positions, the cutting range is increased.

[0051] The upper retaining ring 701 and the lower retaining ring 501 are connected to the tool outer pipe 101 through the upper fixing rib 201 and the lower fixing rib 401. The number of the upper fixing ribs 201 is two, and they are symmetrically arranged at 180 degrees on the side of the upper retaining ring 701. Similarly, the number of the lower fixing ribs 401 is also two, and they are symmetrically arranged at 180 degrees on the side of the lower retaining ring 501.

[0052] In the glass fiber reinforced plastic gas injection and brine removal process string for the salt cavern gas storage according to this embodiment, the fixed ribs serve to support the retaining ring, and the gaps between the fixed ribs allow brine to flow.

[0053] In a preferred embodiment, the annulus between the outer gas injection and brine removal pipe 4 and the production casing 1 is sealed with a packer 2. Multiple hydraulic impeller rotators 3 are connected to the inner pipe, located where salt is likely to precipitate and crystallize, with the number determined based on demand. The various components are connected using oil casing threads.

[0054] After the gas injection and brine removal pipe column is installed, the gas injection and brine removal operation is carried out in reverse circulation mode. Figure 1 As shown in the flow direction 5 of the gas injection and brine discharge, the brine in the salt cavity is discharged to the ground through the glass fiber reinforced plastic gas injection and brine discharge inner pipe 6.

[0055] In addition, a plurality of hydraulic impeller rotators 3 are connected to the inner pipe 6 for gas injection and brine removal. The hydraulic impeller rotators 3 increase the intensity of turbulence of the brine fluid and break the salt crystal nuclei through hydraulic impact rotation, thereby greatly delaying the crystallization of salt inside the brine removal column.

[0056] According to another aspect of the present invention, a method for gas injection and brine removal in a salt cavern gas storage facility using glass fiber reinforced plastics is also provided. The method is implemented using the salt cavern gas storage facility glass fiber reinforced plastics gas injection and brine removal process column described in the above embodiment, and comprises the following steps:

[0057] Assemble and install the glass fiber reinforced plastic gas injection and brine removal process column of the salt cavern gas storage;

[0058] Gas is injected into the brine discharge outer pipe 4 , and under the action of gas pressure, the brine in the salt cavern is discharged through the brine discharge inner pipe 6 .

[0059] In a preferred embodiment, when the brine flows in the brine discharge inner pipe 6, it drives the hydraulic impeller rotator 3 to rotate, and the blades 302 of the hydraulic impeller rotator 3 scrape out the salt crystals.

[0060] Example 1

[0061] A fiberglass reinforced plastic (FRP) gas injection and brine removal process string for a salt cavern gas storage facility comprises an outer brine removal tube 4. The outer tube 4 is a cylindrical structure that extends from the wellhead downhole, with its lower end extending to the upper portion of the salt cavern. In this embodiment, the outer tube 4 is sleeved within and coaxially arranged within a production casing 1. A packer 2 is provided at its lower end to seal the annulus between the production casing 1 and the outer tube 4. The packer 2 also supports the lower end of the outer tube 4.

[0062] Inside the brine discharge outer pipe 4, a brine discharge inner pipe 6 is provided, and the brine discharge inner pipe 6 is coaxially arranged with the brine discharge outer pipe 4. In this embodiment, the lower section of the brine discharge inner pipe 6 extends beyond the brine discharge outer pipe 4 and reaches the lower part of the salt cavern.

[0063] In this way, the annulus between the brine discharge outer pipe 4 and the brine discharge inner pipe 6 serves as the gas injection channel, and the internal channel of the brine discharge inner pipe 6 serves as the brine discharge channel. Since the brine discharge outer pipe 4 is arranged at the upper part of the salt cavern, the injected gas is injected into the upper part of the salt cavern through the gas injection channel from the wellhead. The gas in the upper part of the salt cavern increases and the pressure becomes larger, pushing the brine in the lower part of the salt cavern to flow upward through the brine discharge channel until it is discharged.

[0064] A number of hydraulic impeller rotators 3 are arranged on the brine discharge inner pipe 6. The hydraulic impeller rotators 3 can rotate when the brine flows, and at the same time, the rotation of the impeller can cut the inside of the pipe, so as to scrape off the salt crystals precipitated from the brine. The water wheel rotator is a cylindrical short section, connected in the brine discharge inner pipe 6, and connected to the brine discharge inner pipe 6 at both ends respectively. The brine discharge inner pipe 6 is divided into multiple sections, and two sections are connected by the water wheel rotator. The outer wall of the water wheel rotator is sealed and connected to the brine discharge inner pipe 6, and a water wheel is arranged inside, which can rotate under the drive of the flowing brine, and the blade 302 can cut the salt crystals.

[0065] The brine discharge outer pipe 4 is made of steel material, and the brine discharge inner pipe 6 is made of fiberglass; the hydraulic impeller rotator 3 is made of fiberglass or stainless steel.

[0066] In the fiberglass gas injection and brine discharge process string of the salt cavern gas storage reservoir according to this embodiment, by using the fiberglass material for the gas injection and brine discharge inner pipe 6 string, the inner wall finish is greatly improved, the degree of salt crystallization on the inner pipe surface and the hydraulic loss are reduced, and the brine discharge rate and system efficiency are improved.

[0067] Connecting multiple hydraulic impeller rotators 3 increases the agitation of the brine fluid, increases the turbulence intensity of the brine fluid and the fragmentation of the salt crystal nuclei, and greatly delays the purpose of salt crystallization inside the brine discharge pipe string. This patent measure greatly delays the salt crystallization speed, reduces the frequency of well flushing, reduces the operation cost, improves the gas injection and brine discharge efficiency, and speeds up the construction progress of the gas storage reservoir.

[0068] In one embodiment, the hydraulic impeller rotator 3 is arranged at the position where salt is likely to precipitate crystals. The position where salt is likely to precipitate crystals in the well is obtained based on experience, or determined by indoor experiments and / or computer numerical simulation methods.

[0069] The hydraulic impeller rotator 3 is arranged at the position where salt is likely to precipitate crystals in the well. There is no need to set too many hydraulic impeller rotators 3, only need to set it at the key positions, so that the number of hydraulic impeller rotators 3 can be reduced, the cost can be saved, and it will not affect the flow velocity of the fluid and the rotation speed of the hydraulic impeller rotator.

[0070] In one embodiment, as Figure 2 shown, the hydraulic impeller includes a tool outer tube 101 connected to the brine discharge inner tube 6. The tool outer tube 101 has a cylindrical structure, and a rotating impeller device is provided inside it. The rotating impeller device rotates when the brine flows, and at the same time, the rotating impeller device cuts the salt crystals.

[0071] Two retaining rings are provided inside the tool outer tube 101, namely an upper retaining ring 701 and a lower retaining ring 501. The upper retaining ring 701 and the lower retaining ring 501 are provided at both ends of the rotating impeller device and are rotationally connected. The retaining rings have a cylindrical structure and are connected to the tool outer tube 101 through fixing ribs. Among them, the upper retaining ring 701 is connected to the tool outer tube 101 through an upper fixing rib 201, and the lower retaining ring 501 is connected to the tool outer tube 101 through a lower fixing rib 401.

[0072] The retaining rings have a cylindrical structure, and an annular groove is provided inside them for installing the rotating impeller device. The groove is a groove of a stepped device, and the end is provided with an opening. The rotating impeller device is inserted at the opening of the groove, and the rotating impeller device can rotate relatively within the groove of the retaining ring, or the rotating impeller device is fixedly connected within the groove and can rotate itself. Both methods can be achieved. The upper retaining ring 701 and the lower retaining ring 501 define the position of the rotating impeller device to prevent it from falling off.

[0073] The rotating impeller device includes a core shaft 601 rotatably connecting the upper retaining ring 701 and the lower retaining ring 501. A rotating ring 303 is provided outside the core shaft 601, and a plurality of rotating impellers 301 are provided on the outer wall of the rotating ring 303. Blades 302 are provided outside the rotating impellers 301.

[0074] Among them, the core shaft 601 has a circular tubular structure, and its upper end and lower end are both inserted into the grooves of the retaining rings. The rotating ring 303 is sleeved on the core shaft 601 and can rotate on the core shaft 601. The rotating impellers are provided on the rotating ring 303 and rotate with the rotation of the rotating ring 303. The blades 302 are fixed on the rotating impellers and are inclined. During the flow of the brine, the axial force of the brine is converted into a circumferential force, thereby driving the rotating ring 303 to rotate around the core shaft 601.

[0075] The blades 302 are inclined and can be pushed to rotate when the brine flows through. During the flow of the brine, the salt in it will crystallize on the inner wall of the brine discharge inner tube 6 to form salt crystals. When the blades 302 rotate, the blades 302 can cut the salt crystals, thereby scraping off the salt crystals.

[0076] There are four blades 302 in the rotary impeller device, which are evenly arranged in the circumferential direction of the mandrel 601, and the included angle between two adjacent blades 302 is 90 degrees. The blades 302 can be in the same position or not in the same position in the axial direction of the rotary impeller device. When arranged in the same position, the cutting ability is increased, and when arranged in different positions, the cutting range is increased.

[0077] The upper retaining ring 701 and the lower retaining ring 501 are connected to the tool outer tube 101 through the upper fixing rib 201 and the lower fixing rib 401. The number of the upper fixing ribs 201 is two, and they are symmetrically arranged at 180 degrees on the side surface of the upper retaining ring 701. Similarly, the number of the lower fixing ribs 401 is also two, and they are symmetrically arranged at 180 degrees on the side surface of the lower retaining ring 501.

[0078] In the fiberglass gas injection and brine drainage process string for salt cavern gas storage described in this embodiment, the fixing ribs play a role in supporting the retaining rings, and the gaps between the fixing ribs can allow the brine to flow through.

[0079] The annulus between the gas injection and brine drainage outer tube 4 and the production casing 1 is sealed by a packer 2. The size of the production casing 1 is Φ244.5mm, and the material of the steel gas injection and brine drainage outer tube 4 is steel material, with a size of Φ177.8mm. The fiberglass gas injection and brine drainage inner tube 6 is made of fiberglass, with a size of Φ114.3mm. A plurality of hydraulic impeller rotators 3 are connected to the inner tube, and their positions are where salt is likely to precipitate and crystallize, and the number is determined according to needs. Each part is connected by oil casing threads.

[0080] After the gas injection and brine drainage string is installed, the gas injection and brine drainage operation is carried out in a reverse circulation mode, as shown in Figure 1 the gas injection and brine drainage water flow direction 5 shown. The brine in the salt cavity is discharged to the ground through the fiberglass gas injection and brine drainage inner tube 6. The inner wall of the fiberglass brine drainage inner tube 6 has a high surface finish, with an absolute roughness of 0.0053mm, which is much smaller than the inner surface roughness of the steel pipe, 0.046mm (0.6mm for an old steel pipe). This can greatly reduce the degree of salt crystallization on the inner surface of the inner tube; the inner wall of the fiberglass inner tube is smooth, and the friction factor along the way is 0.0095, which is only half of that of the steel pipe, greatly reducing the hydraulic loss and improving the brine drainage rate and system efficiency.

[0081] In addition, a plurality of hydraulic impeller rotators 3 are connected to the gas injection and brine drainage inner tube 6. The hydraulic impeller rotators 3 increase the turbulence intensity of the brine fluid and the fragmentation of the salt crystal nuclei through hydraulic impact rotation, greatly delaying the purpose of salt crystallization inside the brine drainage string.

[0082] Embodiment 2

[0083] A method for fiberglass gas injection and brine drainage in a salt cavern gas storage, which is realized by using the fiberglass gas injection and brine drainage process string described in the above embodiment, and includes the following steps:

[0084] Assemble the components and install the FRP gas injection and brine drainage process string for the salt cavern gas storage reservoir;

[0085] Inject gas into the outer brine drainage pipe 4. Under the pressure of the gas, the brine in the salt cavern is discharged through the inner brine drainage pipe 6.

[0086] In a preferred embodiment, when the brine flows in the inner brine drainage pipe 6, it drives the hydraulic impeller rotator 3 to rotate, and the blades 302 of the hydraulic impeller rotator 3 scrape the salt crystals.

[0087] It should be understood that the embodiments disclosed in the present invention are not limited to the specific structures, processing steps or materials disclosed herein, but should extend to equivalent alternatives of these features understood by those of ordinary skill in the relevant art. It should also be understood that the terms used herein are only for the purpose of describing specific embodiments and do not imply limitation.

[0088] In the description of the present invention, unless otherwise specified, the meaning of "a plurality" is two or more; the orientation or positional relationships indicated by the terms "upper", "lower", "left", "right", "inner", "outer", "front end", "rear end", "head", "tail", etc. are based on the orientation or positional relationships shown in the drawings, and are 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 thus cannot be construed as a limitation of the present invention. In addition, the terms "first", "second", "third", etc. are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0089] In the description of the present invention, it should be noted that unless otherwise clearly defined and limited, the terms "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood in specific cases.

[0090] Certain terms are used throughout the present application document to refer to specific system components. As those skilled in the art will recognize, the same components can generally be referred to by different names, and thus the present application document does not intend to distinguish components that are only different in name but not in function. The phrase "an embodiment" or "embodiments" mentioned in the specification means that the specific features, structures or characteristics described in connection with the embodiments are included in at least one embodiment of the present invention. Therefore, the phrases "an embodiment" or "embodiments" that appear throughout the specification do not necessarily all refer to the same embodiment.

[0091] Embodiments of the present invention are given by way of example and description, and are not exhaustive or limit the present invention to the disclosed forms. Many modifications and variations are obvious to those of ordinary skill in the art. The embodiments are chosen and described in order to better illustrate the principles and practical applications of the present invention, and to enable those of ordinary skill in the art to understand the present invention so as to design various embodiments with various modifications suitable for a particular purpose.

[0092] Although the preferred embodiments of the present invention have been described, additional changes and modifications can be made to these embodiments by those skilled in the art once they learn the basic inventive concept. Therefore, the appended claims are intended to be construed to include the preferred embodiments as well as all changes and / or modifications that fall within the scope of the present invention. All changes and / or modifications made in accordance with the embodiments of the present invention should be covered within the protection scope of the present invention.

Claims

1. A glass fiber reinforced plastic gas injection and brine drainage process string for a salt cavern gas storage reservoir, characterized in that, Comprising: A brine discharge outer pipe (4), the brine discharge outer pipe (4) is coaxially arranged inside the production casing (1); and A brine discharge inner pipe (6) arranged inside the brine discharge outer pipe (4), the lower end of the brine discharge inner pipe (6) extends to the lower part of the salt cavern; Wherein, a number of hydraulic impeller rotators (3) are arranged on the brine discharge inner pipe (6), and the brine flowing in the brine discharge inner pipe (6) drives the water wheel rotator to rotate so as to cut the salt crystals.

2. The FRP gas injection and brine drainage process string for salt cavern gas storage described in claim 1, wherein, The brine discharge outer pipe (4) is made of steel material, and the brine discharge inner pipe (6) is made of fiberglass; the hydraulic impeller rotator (3) is made of fiberglass or stainless steel.

3. The glass fiber reinforced plastic gas injection and brine drainage process string for salt cavern gas storage described in claim 2, wherein The hydraulic impeller rotator (3) is arranged at the position where salt is likely to precipitate and crystallize.

4. The glass fiber reinforced plastic gas injection and brine drainage process string for salt cavern gas storage according to claim 3, wherein The hydraulic impeller rotator (3) includes a tool outer pipe (101), and a rotating impeller device is arranged inside the tool outer pipe (101), and the rotating impeller device rotates along with the flow of the brine and cuts the salt crystals at the same time.

5. The glass fiber reinforced plastic gas injection and brine drainage process string for salt cavern gas storage described in claim 4, wherein The upper part inside the tool outer pipe (101) is connected to an upper retaining ring (701) through an upper fixing rib (201), and the lower part is connected to a lower retaining ring (501) through a lower fixing rib (401), and the rotating impeller device is rotatably connected between the upper retaining ring (701) and the lower retaining ring (501).

6. The glass fiber reinforced plastic gas injection and brine drainage process string for salt cavern gas storage described in claim 5, characterized in that, The rotating impeller device includes a core shaft (601) rotatably connected to the upper retaining ring (701) and the lower retaining ring (501), a rotating ring (303) is arranged outside the core shaft (601), a number of rotating impellers (301) are arranged on the outer wall of the rotating ring (303), and blades (302) are arranged outside the rotating impellers.

7. The glass fiber reinforced plastic gas injection and brine drainage process string for salt cavern gas storage described in claim 6, characterized in that, The number of the blades (302) is four, and they are evenly arranged in the circumferential direction of the core shaft (601); the number of the upper fixing ribs (201) is two, and they are arranged on both sides of the upper retaining ring (701) at 180 degrees, and the number of the lower fixing ribs (401) is two, and they are arranged on both sides of the lower retaining ring (501) at 180 degrees.

8. The glass fiber reinforced plastic gas injection and brine drainage process string for salt cavern gas storage according to claim 7, characterized in that, A packer (2) is arranged at the lower part of the brine discharge outer pipe (4) to seal the annulus between the brine discharge outer pipe (4) and the production casing (1).

9. A method for injecting gas and discharging brine in a salt cavern gas storage reservoir with a glass fiber reinforced plastic, characterized in that, Realized by using the fiberglass gas injection and brine discharge process string for salt cavern gas storage described in any one of claims 1 to 8, which includes: Assembling and installing the fiberglass gas injection and brine discharge process string for salt cavern gas storage; Injecting gas into the brine discharge outer pipe (4), and under the pressure of the gas, the brine in the salt cavern is discharged through the brine discharge inner pipe (6).

10. The glass fiber reinforced plastic gas injection and brine drainage process method for the salt cavern gas storage reservoir according to claim 9, characterized in that, When the brine flows in the brine discharge inner pipe (6), it drives the hydraulic impeller rotator (3) to rotate, and the blades (302) of the hydraulic impeller rotator (3) scrape the salt crystals.

Images