Multifunctional short section for sediment and brine discharge of salt cavity and use method of multifunctional short section

Abstract

The invention discloses a multifunctional short section for sediment and brine discharge of a salt cavity. The multifunctional short section comprises a tool body, at least one group of bypass holes are formed in the side wall of the cavity of the tool body; a temporary blocking blocking piece, an inner sealing gasket, an outer sealing gasket and a pressing ring are arranged in the bypass hole, the temporary blocking blocking piece is arranged between the inner sealing gasket and the outer sealing gasket, and the pressing ring is detachably connected with the bypass hole and tightly presses the inner sealing gasket, the temporary blocking blocking piece and the outer sealing gasket. The temporary blocking separation blade is made of a soluble metal material, and the self-dissolving time of the temporary blocking separation blade in the brine environment is longer than the preset time. After the integrated pipe column is connected with the multifunctional short section, the integrated operation of drilling in the salt cavity sediment and discharging brine and expanding capacity can be implemented, and the working procedures are saved; the multifunctional short section can provide a good liquid inlet channel for brine and small-particle-size sediment particles in sediment, so that the brine in a salt cavity, especially the sediment, is discharged, efficient brine discharging in the sediment of the salt cavity is guaranteed, and effective utilization of sediment gap space and effective improvement of the gas storage capacity of the cavity are achieved.

Description

Technical Field

[0001] The invention relates to the field of salt cavern gas storage construction, in particular to a multifunctional short section for salt cavern sediment brine discharge and a use method thereof. Background Art

[0002] Salt cavern gas storages at home and abroad are all built in high-grade salt mines with an insoluble content of less than 25%. However, according to years of research by gas storage construction units, it is difficult to find such high-grade salt mines. In order to meet the urgent requirements of the country for gas storage, low-grade salt mines with an impurity content of more than 25% are further selected for construction. In low-grade salt mines, the traditional water-soluble cavity-making technology of salt cavern gas storage is used. Fresh water is injected from the ground into the underground salt layer to dissolve the solid sodium chloride minerals to form brine containing sodium ions and chloride ions. The brine is then mined to the ground, and finally a salt cavity is formed in the underground salt layer. Since the salt layer is impure and contains water-insoluble minerals such as mud and gypsum, these minerals absorb water and expand after being released from the salt layer, and are loosely accumulated at the bottom of the salt cavity to form sediment. The accumulation of insoluble matter and internal brine occupy a large amount of storage capacity. After gas injection and brine removal, only a small-scale gas reservoir can be formed, resulting in a low proportion of effective space in the salt cavity and low actual utilization of the salt layer. According to statistics, in areas such as Jintan, Chuzhou, Huai'an and Pingdingshan under construction or planned to be built in China, after the salt cavern gas storage wells are constructed by the water dissolution method, the volume of insoluble sediment accumulation in the salt cavern usually accounts for 1 / 3 to 2 / 3 of the total volume of the cavity, resulting in nearly half of the volume of the salt cavern cavity not being effectively utilized.

[0003] In recent years, a large number of domestic scholars have also conducted experimental tests and analytical studies on the physical properties and void space of salt cavern sediments. It is generally believed that the void space of the sediment at the bottom of the salt cavern gas storage has great potential for utilization and gas storage. Zheng Yali and other scholars measured the maximum porosity of the sediment at the bottom of the cavity through indoor compaction and gas drive simulation experiments, and found that the maximum porosity of the sediment at the bottom of the cavity was at least 42.8% to 50.2%, and the residual porosity under the deadweight pressure of the sediment was 16.7%. Ren Zhongxin and other scholars established a cumulative void volume model and calculation method, and concluded that the overall porosity of the deposits in the dissolution cavity stage of a salt cavern gas storage well in Jintan was 45.73%, and the porosity obtained from the on-site sonar cavity measurement data of the well was 42.66%. Han Jiepeng, Liu Jianyi and other scholars combined indoor physical experimental simulation and mathematical modeling to obtain a porosity of 36.41% to 43.11% for the spherical sediment accumulation, and an average expandable accumulation volume of 26.32%, and believed that bound water existed in the accumulation. Therefore, if the pore space of sediment can be fully utilized for gas storage, the economic efficiency of salt cavern gas storage can be significantly improved.

[0004] Salt cavern gas storage facilities abroad are generally built in huge salt domes, with high salt rock content, few interlayers, and low insoluble matter content. Therefore, there is no research on drilling and draining brine in salt cavern sediments abroad. At present, the traditional gas injection and brine drainage method is to lower the brine drainage column from the upper part of the salt cavity, and the brine drainage column cannot be lowered into the sediment, so the brine in the pores of the sediment cannot be discharged; and the drilling operation and brine drainage operation need to be carried out separately, and it is impossible to complete the operation in one drilling trip, which has low work efficiency. Summary of the invention

[0005] In order to better realize the integrated operation of drilling and brine drainage in the salt cavity and effectively discharge the brine in the salt cavity sediment, the embodiment of the present application provides a multifunctional short section for draining brine from the salt cavity sediment and a method of using the same.

[0006] In a first aspect, the present application proposes a multifunctional short section for draining brine from salt chamber sediment, comprising: a tool body;

[0007] At least one group of bypass holes is provided on the cavity side wall of the tool body;

[0008] The bypass hole is provided with a temporary blocking piece, an inner sealing gasket, an outer sealing gasket and a pressure ring, the temporary blocking piece is arranged between the inner sealing gasket and the outer sealing gasket, the pressure ring is detachably connected to the bypass hole, and presses the inner sealing gasket, the temporary blocking piece and the outer sealing gasket;

[0009] The temporary blocking piece is made of a soluble metal material, and the self-dissolution time of the temporary blocking piece in a brine environment is greater than a preset time.

[0010] In one or some optional implementations of the embodiment of the present application, it further includes: a slit screen; the slit screen is arranged on the outer surface of the tool body, and the slit screen covers the bypass hole.

[0011] In one or some optional implementations of the embodiment of the present application, the aperture of the sieve holes of the slotted screen close to the bypass hole is larger than the aperture on the side away from the bypass hole.

[0012] In one or some optional implementations of the embodiment of the present application, the tool body is cylindrical;

[0013] The tool body is provided with a plurality of groups of bypass holes along the axial direction;

[0014] Each group of bypass holes includes a plurality of bypass holes that are equidistantly distributed along the same circumferential surface of the tool body.

[0015] In one or some optional implementations of the embodiment of the present application, the upper end surface of the pressure ring is provided with at least one group of centrally symmetrical notches.

[0016] In one or some optional implementations of the embodiment of the present application, it further includes a first joint and a second joint, and the first joint and the second joint are respectively arranged at two ends of the tool body.

[0017] In one or some optional implementations of the embodiments of the present application, the multifunctional short section has a compressive strength greater than 40 MPa, a temperature resistance exceeding 100°C, a shear strength greater than 2414 KN, and an air sealing pressure greater than 21 MPa.

[0018] In a second aspect, the present application proposes an integrated pipe column, including the multifunctional short section for draining brine from salt chamber sediment.

[0019] In one or some optional implementations of the embodiment of the present application, a drilling tool and a brine removal sleeve are also included;

[0020] The drilling tool, the multifunctional short joint and the brine removal sliding sleeve are connected in sequence from bottom to top through oil pipes.

[0021] In a third aspect, the present application proposes a method for injecting gas and draining brine from a salt cavity using the multifunctional short section for draining brine from salt cavity sediment, comprising the following steps:

[0022] S1. Connect the multifunctional short section to the integrated pipe column, and lower the integrated pipe column into the salt cavity; the integrated pipe column is connected with a drilling tool, the multifunctional short section and a brine removal sleeve;

[0023] S2, when the integrated pipe string reaches a predetermined position on the sediment surface of the salt cavity, the surface delivery pump is turned on to deliver drilling fluid into the integrated pipe string, and the drilling tool is driven by the drilling fluid to drill downward along the sediment. During this process, the bypass hole on the multifunctional short joint is blocked by a temporary blocking piece for transporting drilling fluid;

[0024] S3. After completing the drilling operation in the salt cavity sediment, a ball is dropped into the salt cavity to open the brine drainage sleeve to make it in a through state, and gas is injected into the salt cavity for displacement. The brine enters the integrated pipe string through the brine drainage sleeve and is discharged to the ground.

[0025] S4. When the gas-brine interface gradually descends to approach the brine discharge sleeve, the ball is dropped to close the brine discharge sleeve, and when the temporary blocking piece is completely self-dissolved and the bypass hole is in a through state, gas is injected into the salt cavity for displacement, and the brine enters the integrated pipe column through the bypass hole, and the residual brine above the sediment surface of the salt cavity and the brine in the sediment are gradually discharged to the ground.

[0026] The beneficial effects of the above technical solution provided by the embodiment of the present application include at least:

[0027] After the water-soluble cavity making of the salt cavern gas storage reservoir is completed, the integrated pipe column is used to connect the multifunctional short section of the present application to implement the integrated operation of drilling in the salt cavern sediment and draining brine and expanding the capacity, saving the process and solving the problem that the prior art cannot complete the drilling and draining brine operations in one trip, and the work efficiency is low. When implementing sediment drilling, the multifunctional short section of the present application can provide a good conveying channel for the drilling fluid; when implementing the gas injection and brine draining operation in the sediment, the multifunctional short section of the present invention can provide a good liquid inlet channel for the brine in the sediment and the small-diameter sediment particles, thereby draining the brine in the salt cavity, especially in the sediment, ensuring efficient brine drainage in the salt cavity sediment, and realizing the effective utilization of the sediment void space and the effective improvement of the cavity gas storage capacity.

[0028] Other features and advantages of the present application will be described in the subsequent description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present application can be realized and obtained by the structures specifically pointed out in the written description, claims, and drawings.

[0029] The technical solution of the present application is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The accompanying drawings are used to provide a further understanding of the present application and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the present application and do not constitute a limitation of the present application. In the accompanying drawings:

[0031] Figure 1 It is a schematic diagram of the structure of the multifunctional short section described in this application;

[0032] Figure 2 is a cross-sectional view of the bypass hole position of the multifunctional short joint described in the present application;

[0033] In the figure, 1. tool body, 2. bypass hole, 3. temporary blocking plate, 4. slit screen, 5. pressure ring, 6. first joint, 7. second joint, 8. inner sealing gasket, 9. outer sealing gasket. DETAILED DESCRIPTION

[0034] In the following description, specific details such as specific system structures, technologies, etc. are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present application. However, it should be clear to those skilled in the art that the present application may also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to prevent unnecessary details from obstructing the description of the present application.

[0035] It should be understood that when used in the present specification and the appended claims, the term "comprising" indicates the presence of described features, wholes, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or combinations thereof.

[0036] It should also be understood that the term “and / or” used in the specification and appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0037] In addition, in the description of the present application specification and the appended claims, the terms "first", "second", "third", etc. are only used to distinguish the descriptions and cannot be understood as indicating or implying relative importance.

[0038] References to "one embodiment" or "some embodiments" etc. described in the specification of this application mean that one or more embodiments of the present application include specific features, structures or characteristics described in conjunction with the embodiment. Therefore, the statements "in one embodiment", "in some embodiments", "in some other embodiments", "in some other embodiments", etc. that appear in different places in this specification do not necessarily refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in other ways. The terms "including", "comprising", "having" and their variations all mean "including but not limited to", unless otherwise specifically emphasized in other ways.

[0039] It should be understood that the size of the serial numbers of the steps in the following embodiments does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0040] In order to illustrate the technical solution of the present application, a specific embodiment is provided below for illustration.

[0041] The inventors have discovered that after the target salt layer section is drilled and the water-soluble method is used to create a cavern, insoluble sediment usually accumulates at the bottom of the salt cavern, occupying more than 1 / 3 of the volume of the salt cavern. The interior is filled with brine, so that nearly half of the volume of the salt cavern cannot be effectively utilized. In the prior art, a brine drainage string is usually lowered from the upper part of the salt cavern. Since the brine drainage string cannot be lowered into the sediment, the brine in the pores of the sediment cannot be discharged. Furthermore, the drilling operation and the brine drainage operation need to be performed separately, and it is impossible to complete the operation in one drilling trip, resulting in low work efficiency.

[0042] In order to effectively utilize this part of the sediment gap and expand the effective gas storage space of the salt cavern cavity, the inventor has made this application after further research and development, providing a multifunctional short section for salt cavity sediment brine drainage and its use method, and using an integrated pipe string to connect the multifunctional short section of this application to implement integrated operations of drilling in salt cavity sediment and gas injection and brine drainage.

[0043] The following describes it in detail through specific embodiments.

[0044] Embodiment 1:

[0045] The present application embodiment provides a multifunctional short section for draining brine from salt chamber sediment, referring to Figure 1 As shown, it includes: a tool body 1;

[0046] The cavity side wall of the tool body 1 is provided with at least one group of bypass holes 2;

[0047] The bypass hole 2 is provided with a temporary blocking piece 3, an inner sealing gasket 8, an outer sealing gasket 9 and a pressure ring 5, wherein the temporary blocking piece 3 is arranged between the inner sealing gasket 8 and the outer sealing gasket 9, and the pressure ring 5 is detachably connected to the bypass hole 2 and presses the inner sealing gasket 8, the temporary blocking piece 3 and the outer sealing gasket 9;

[0048] The temporary blocking piece 3 is made of a soluble metal material, and the self-dissolution time of the temporary blocking piece 3 in a brine environment is greater than a preset time.

[0049] In the embodiment of the present application, the multifunctional short section includes a tool body 1, and at least one group of bypass holes 2 are provided on the side wall of the cavity of the tool body 1. The bypass holes 2 are provided with inner sealing gaskets 8, temporary blocking pieces 3, outer sealing gaskets 9 and pressure rings 5 ​​from inside to outside. The inner sealing gaskets 8, temporary blocking pieces 3 and outer sealing gaskets 9 are compressed by the pressure rings 5. The pressure rings 5 ​​can be fixed in the bypass holes 2 by, but not limited to, threaded connection, to fix the temporary blocking pieces 3. The tool body 1 of the multifunctional short section can be connected to the pipe string used for salt cavity drilling and brine discharge in the prior art to realize the integrated operation of salt cavity sediment drilling and brine discharge.

[0050] In the embodiment of the present application, the cross-sectional shape of the bypass hole 2 is preferably circular, the shapes of the inner sealing gasket 8 and the outer sealing gasket 9 are preferably circular rings, the sizes of the inner sealing gasket 8 and the outer sealing gasket 9 are consistent, preferably: outer diameter 40mm, inner diameter 35mm, thickness 1.5mm, and the pressure ring 5 is preferably in the shape of a circular ring, and its size is preferably an outer diameter of 42mm and a thickness of 7.5mm.

[0051] In the embodiment of the present application, the material of the temporary blocking piece 3 is a soluble metal material, and the soluble metal material can be used but not limited to the soluble magnesium-lithium alloy material proposed in the application publication number CN113667871A; the self-dissolution time of the temporary blocking piece 3 in the brine environment is greater than the preset time, and the preset time is the time when the multifunctional short joint is used with the pipe string for drilling salt cavity sediment. Assuming that the brine environment in the salt cavity sediment is 50°C saturated brine, and the pipe string drilling time is expected to be 50h, the self-dissolution time of the temporary blocking piece 3 is greater than 55h.

[0052] During the drilling operation, the temporary blocking piece 3 does not dissolve by itself, and the temporary blocking piece 3 seals the bypass hole 2, so that the multifunctional short joint is in a closed state. The multifunctional short joint can be used as a transportation pipeline, which can transport liquids required in the drilling operation, such as drilling fluid. Since the inner sealing gasket 8 and the outer sealing gasket 9 are provided, the sealing effect of the multifunctional short joint can be guaranteed. A better sealing effect is one of the prerequisites for the multifunctional short joint to be used as a transportation pipeline; when drilling to the salt cavity sediment, the multifunctional short joint is in the salt cavity sediment. After the temporary blocking piece 3 dissolves by itself, the temporary blocking piece 3 releases the sealing effect on the bypass hole 2, so that the multifunctional short joint is in a through state. The multifunctional short joint plays the role of brine discharge. The gas drive method in the prior art can be used, but is not limited to it. Gas is injected into the salt cavity to make the brine in the sediment flow into the pipe string through the bypass hole 2 and be discharged to the ground. Through the embodiments of the present application, the pipe column used for salt cavity drilling and brine drainage in the prior art is combined with the multifunctional short section, which can realize the salt cavity drilling and brine drainage operations at the same time, save process steps and improve work efficiency; and the multifunctional short section can enter the sediment to discharge the brine therein, which can solve the problem that the brine drainage pipe column in the prior art cannot be lowered into the sediment, resulting in the inability to discharge the brine, and the gaps in the sediment can be effectively utilized to expand the effective gas storage space of the salt cavern cavity.

[0053] In a specific embodiment, the multifunctional pup joint further includes: a slotted screen 4 ; the slotted screen 4 is disposed on the outer surface of the tool body 1 , and the slotted screen 4 covers the bypass hole 2 .

[0054] In the embodiment of the present application, the slit screen 4 can be fixed to the outer surface of the tool body 1 by means of but not limited to bolt connection, or screen pressure rings can be set at both ends of the slit screen 4 to fix the slit screen 4 to the tool body 1; the slit screen 4 is provided with a plurality of sieve holes, and its function is to filter the brine and sediment particles flowing into the bypass hole 2 during the gas injection and brine removal operation in the salt cavity sediment after the temporary blocking piece 3 dissolves itself, so as to prevent large sediment particles from entering the multifunctional short section and causing blockage thereof.

[0055] In a specific embodiment, the aperture of the sieve hole of the slotted screen 4 is larger on the side close to the bypass hole 2 than on the side away from the bypass hole 2, that is, the aperture of the inlet end of the sieve hole is smaller than the aperture of the outlet end of the sieve hole, so that the inflow section of the brine entering the sieve hole is smaller than the outflow section. The aperture of the inlet end of the sieve hole is preferably 1.5-1.8 mm, the aperture of the outlet end of the sieve hole is preferably 2-2.5 mm, and the slit length of the sieve hole is preferably 5-8 mm.

[0056] In the embodiment of the present application, the working principle and effect of the sieve hole are as follows: the brine in the salt cavity sediment enters the multifunctional short section through the sieve hole and the bypass hole 2 in turn, and the sieve hole can block the large-particle sediment (whose particle size is larger than the aperture of the inlet end of the sieve hole) from entering the multifunctional short section, thereby preventing the large-particle sediment from clogging the multifunctional short section; for small-particle sediment (whose particle size is smaller than the aperture of the inlet end of the sieve hole), it will enter the sieve hole with the brine. Since the inflow section formed by the above-mentioned sieve hole is smaller than its outflow section, the flow rate of the brine entering the sieve hole is relatively large, and its sand-carrying capacity is relatively strong, which prevents small-particle sediment from gathering at the inlet end of the sieve hole and causing blockage. At the same time, since the outflow section is larger, small-particle sediment is not easy to gather in the sieve hole and cause blockage. Therefore, the sieve hole has a filtering effect on the brine and sediment flowing through, which can effectively prevent the multifunctional short section from being blocked.

[0057] In a specific embodiment, the tool body 1 is cylindrical; a plurality of groups of bypass holes are arranged on the tool body 1 along the axial direction; each group of bypass holes includes a plurality of bypass holes 2 equidistantly distributed along the same circumferential surface of the tool body 1. Figure 2 As shown, taking the example of setting three bypass holes 2 in each bypass hole group, the three bypass holes 2 are evenly distributed at 120° on the same circumferential surface of the tool body 1; the distance between each group of bypass holes is preferably set at 200-250mm, and the flow diameter of each bypass hole 2 is 35mm.

[0058] In a specific embodiment, the upper end surface of the pressing ring 5 is provided with at least one group of centrally symmetrical notches, so that loading and unloading tools can be inserted into the notches to facilitate installation or removal of the pressing ring 5.

[0059] In a specific embodiment, the multifunctional nipple further includes a first joint 6 and a second joint 7, and the first joint 6 and the second joint 7 are respectively arranged at both ends of the tool body 1. The first joint 6 and the second joint 7 can be connected to a pipe string used for salt cavity drilling and brine removal by a threaded connection method in the prior art, and the multifunctional nipple is fixedly installed at a predetermined position of the pipe string, and is lowered into the salt cavity together with the pipe string to perform drilling and brine removal operations.

[0060] In a specific embodiment, the multifunctional short joint has a compressive strength greater than 40MPa, a temperature resistance greater than 100°C, a shear strength greater than 2414KN, and a gas sealing pressure greater than 21MPa. When the multifunctional short joint is used for drilling and brine removal in salt cavity, the performance of the multifunctional short joint can meet the performance requirements of the transportation pipeline and provide a good transportation channel for the drilling fluid.

[0061] Embodiment 2:

[0062] Based on the same inventive concept, an integrated pipe column is also proposed, which includes the above-mentioned multifunctional short section for draining brine from salt cavity sediment. The multifunctional short section is connected to the integrated pipe column and lowered into the sediment in the salt cavity to perform brine drainage operations, making full use of the gaps in the sediment and expanding the effective gas storage space of the salt cavern cavity.

[0063] In a specific embodiment, the integrated tubing string can be connected to but is not limited to various tubing strings in the prior art. For salt cavity drilling and brine drainage operations, the integrated tubing string also includes a drilling tool and a brine drainage sleeve; the drilling tool, the multifunctional short section, and the brine drainage sleeve are connected in sequence from bottom to top through oil pipes. The integrated tubing string plays the dual role of drilling and brine drainage, saving processes and solving the problems of complex production and injection processes and low work efficiency in the prior art.

[0064] In the embodiment of the present application, the brine above the sediment surface of the salt cavity is discharged by setting a brine discharge sleeve. Since the conventional brine discharge sleeve cannot enter the sediment, when the integrated pipe string is used for brine discharge operation, the brine discharge sleeve is arranged above the sediment surface, and the brine discharge sleeve can be opened by throwing a ball in the prior art, and the gas drive method in the prior art can be used, but not limited to, to inject gas into the salt cavity, so that the brine can enter the integrated pipe string from the brine discharge sleeve, thereby discharging the brine above the sediment surface to the ground.

[0065] In the embodiment of the present application, the multifunctional short joint can be used not only as a transport pipeline, but also as a brine discharge pipeline for discharging brine below the sediment surface. Specifically, during the salt cavity sediment drilling operation, the temporary blocking piece 3 is not dissolved, so that the multifunctional short joint is in a closed state, which can be used as a transport pipeline to transport drilling fluid for the drilling operation; when the salt cavity sediment drilling operation is completed and the brine needs to be discharged, the temporary blocking piece 3 is self-dissolved, and the bypass hole 2 is in a through state. The gas drive method in the prior art can be adopted but not limited to inject gas into the salt cavity, and the brine (including the brine remaining on the sediment surface and the brine below the sediment surface) enters the integrated pipe string from the bypass hole 2 and is discharged to the ground.

[0066] Embodiment three:

[0067] Based on the same inventive concept, a method for injecting gas and draining brine from a salt cavity using a multifunctional short joint for draining brine from salt cavity sediment is proposed, comprising the following steps:

[0068] S1. Install the inner sealing gasket 8, the temporary blocking plate 3 and the outer sealing gasket 9 into the bypass hole 2 in sequence, and fix the pressure ring 5 in the bypass hole 2 by threaded connection to fix the positions of the inner sealing gasket 8, the temporary blocking plate 3 and the outer sealing gasket 9; connect the first joint 6 and the second joint 7 at both ends of the multifunctional short section with the integrated pipe string, so as to connect the multifunctional short section with the integrated pipe string, and lower the integrated pipe string into the salt cavity; the integrated pipe string is connected with a drilling tool, the multifunctional short section and the brine removal sleeve. Specifically, according to the on-site requirements, the integrated pipe string is connected with the drilling tool, the weighted oil pipe, the oil pipe string, the multifunctional short section, the brine removal sleeve, the multifunctional hand release and the oil pipe string in sequence from bottom to top;

[0069] S2. When the integrated pipe string reaches the predetermined position of the sediment surface in the salt cavity, the surface delivery pump is turned on to deliver drilling fluid into the integrated pipe string, and the drilling tool is driven by the drilling fluid to drill downward along the sediment. During this process, the bypass hole 2 on the multifunctional short section is blocked by the temporary blocking piece 3 for transporting the drilling fluid;

[0070] S3. After completing the drilling operation in the salt cavity sediment, drop a ball into the salt cavity, open the brine drainage sleeve, and make it in a through state. Inject gas into the salt cavity for displacement. The brine enters the integrated pipe string through the brine drainage sleeve and is discharged to the ground, so that the brine above the sediment surface in the salt cavity is discharged to the ground;

[0071] S4, when the gas-brine interface gradually drops to close the brine discharge sleeve, the ball is thrown to close the brine discharge sleeve, and when the temporary blocking piece 3 is completely self-dissolved, the bypass hole 2 is in a through state, and gas is injected into the salt cavity for displacement. The brine enters the integrated pipe column from the bypass hole 2, and the residual brine above the salt cavity sediment surface and the brine in the sediment are gradually discharged to the ground. At the same time, during the gas injection and brine discharge process, the slit screen 4 set on the outer surface of the multifunctional short-section tool body 1 has a filtering effect on the brine and sediment particles flowing through, which can prevent the brine from carrying large-diameter sediment particles into the multifunctional short section and causing blockage.

[0072] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A multifunctional short section for draining brine from salt chamber sediment, characterized in that: include: Tool body; At least one group of bypass holes is provided on the cavity side wall of the tool body; The bypass hole is provided with a temporary blocking piece, an inner sealing gasket, an outer sealing gasket and a pressure ring, the temporary blocking piece is arranged between the inner sealing gasket and the outer sealing gasket, the pressure ring is detachably connected to the bypass hole, and presses the inner sealing gasket, the temporary blocking piece and the outer sealing gasket; The temporary blocking piece is made of a soluble metal material, and the self-dissolution time of the temporary blocking piece in a brine environment is greater than a preset time.

2. The multifunctional short section for draining brine from salt chamber sediment according to claim 1 is characterized in that: Also includes: Slotted screen; The slotted screen is arranged on the outer surface of the tool body, and the slotted screen covers the bypass hole.

3. The multifunctional short section for draining brine from salt chamber sediment according to claim 2 is characterized in that: The aperture of the sieve holes of the slotted screen close to the bypass hole is larger than the aperture of the sieve holes away from the bypass hole.

4. The multifunctional short section for draining brine from salt chamber sediment according to claim 1 or 3, characterized in that: The tool body is cylindrical; The tool body is provided with a plurality of groups of bypass holes along the axial direction; Each group of bypass holes includes a plurality of bypass holes that are equidistantly distributed along the same circumferential surface of the tool body.

5. The multifunctional short section for draining brine from salt chamber sediment according to claim 4 is characterized in that: The upper end surface of the pressure ring is provided with at least one group of centrally symmetrical notches.

6. The multifunctional short section for draining brine from salt chamber sediment according to claim 1 or 5, characterized in that: It also includes a first joint and a second joint, wherein the first joint and the second joint are respectively arranged at two ends of the tool body.

7. The multifunctional short section for draining brine from salt chamber sediment according to claim 6 is characterized in that: The multifunctional short section has a compressive strength greater than 40 MPa, a temperature resistance exceeding 100° C., a shear strength greater than 2414 KN, and an air sealing pressure greater than 21 MPa.

8. An integrated pipe string, characterized in that: A multifunctional short section for draining brine from salt cavity sediments comprising any one of claims 1 to 7.

9. The integrated pipe string according to claim 8, characterized in that: It also includes drilling tools and brine removal sleeves; The drilling tool, the multifunctional short joint and the brine removal sliding sleeve are connected in sequence from bottom to top through oil pipes.

10. A method for injecting gas and draining brine from a salt cavity using the multifunctional short section for draining brine from salt cavity sediments as claimed in any one of claims 1 to 7, characterized in that: The following steps are involved: S1. Connect the multifunctional short joint to the integrated pipe string, and lower the integrated pipe string into the salt cavity; the integrated pipe string is connected with a drilling tool, the multifunctional short joint and a brine removal sleeve; S2, when the integrated pipe string reaches a predetermined position on the sediment surface of the salt cavity, the surface delivery pump is turned on to deliver drilling fluid into the integrated pipe string, and the drilling tool is driven by the drilling fluid to drill downward along the sediment. During this process, the bypass hole on the multifunctional short joint is blocked by a temporary blocking piece for transporting drilling fluid; S3. After completing the drilling operation in the salt cavity sediment, a ball is dropped into the salt cavity to open the brine drainage sleeve to make it in a through state, and gas is injected into the salt cavity for displacement. The brine enters the integrated pipe string through the brine drainage sleeve and is discharged to the ground. S4. When the gas-brine interface gradually descends to approach the brine discharge sleeve, the ball is dropped to close the brine discharge sleeve, and when the temporary blocking piece is completely self-dissolved and the bypass hole is in a through state, gas is injected into the salt cavity for displacement, and the brine enters the integrated pipe column through the bypass hole, and the residual brine above the sediment surface of the salt cavity and the brine in the sediment are gradually discharged to the ground.

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