A gas injection and brine removal process column for salt cavern gas storage

Abstract

The present invention provides a process pipe column for gas injection and brine removal in a salt cavern gas storage, comprising a gas injection pipe, a brine discharge pipe and a release handle. The gas injection pipe is sleeved outside the brine discharge pipe, and the release handle is placed inside the brine discharge pipe. A telescopic involute-shaped trumpet tube is provided on the end of the brine discharge pipe close to the release handle. When the telescopic involute-shaped trumpet tube is lowered into the gas injection pipe, the telescopic involute-shaped trumpet tube can maintain a contracted state to form a cylindrical tube, and can be opened into a trumpet tube when the telescopic involute-shaped trumpet tube passes through the gas injection pipe and enters the salt cavity. The bottom diameter of the brine discharge pipe column is increased, and the flow rate at the pipe mouth is effectively reduced under the condition of a constant brine discharge flow rate. The process pipe column provided by the present invention reduces the safe distance between the gas-brine interface and the brine discharge pipe mouth to ensure that the natural gas is not carried out, so that the allowable gas-brine interface position becomes deeper, which is conducive to discharging more brine volume and increasing the effective volume of the gas storage reservoir.

Description

Technical Field

[0001] The invention relates to the technical field of gas injection and brine removal in salt cavern gas storage, and in particular to a gas injection and brine removal process column in a salt cavern gas storage. Background Art

[0002] Gas injection and brine removal are key processes before salt cavern gas storage enters the operational stage. During the gas injection and brine removal process, the smooth discharge of brine is the key to the formation of a gas storage reservoir. As the brine removal proceeds, the distance between the gas-brine interface and the brine removal pipe orifice gradually decreases, and the cavity bottom diameter is also smaller, which may form a vortex at the brine removal pipe orifice, causing the natural gas to be carried out. The removal of natural gas will pose a safety hazard to the gas injection and brine removal process. During on-site construction, a certain vortex is usually caused at the pipe orifice. In order to prevent the natural gas from being carried out, it is generally required to maintain a certain safety distance between the brine removal pipe column and the gas-brine interface. The deeper the brine removal pipe column is, the more brine will be discharged, and the larger the effective volume of the cavity formed.

[0003] Domestic and foreign scholars have studied the completion string, brine drainage method, horizontal wellbore construction, etc. of salt cavern gas storage. In order to solve the problem of how to drain as much brine as possible from the bottom of the cavity, they have adopted continuous tubing string devices, built horizontal cavity salt cavern gas storage, integrated brine drainage string and injection and production string, etc., which have solved the problem of gas injection and brine drainage in salt cavern gas storage to a certain extent. However, there is currently a lack of research on improving the process structure of the lower end of the brine drainage string and improving the depth of the gas injection and brine drainage string. In the construction of gas injection and brine drainage in salt cavern gas storage, how to optimize the process string to reduce the gas-brine interface more while ensuring safety is an urgent problem to be solved. Summary of the invention

[0004] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a salt cavern gas storage gas injection and brine removal process pipe column, which can effectively reduce the flow rate of water at the pipe mouth at the lower end of the brine removal pipe column without changing the brine removal flow rate by optimizing the expandable trumpet shape at the lower end of the brine removal pipe column, and by reducing the allowed safe distance between the gas-brine interface and the pipe mouth, the gas-brine interface is allowed to drop more, more brine volume is discharged, and the effective working volume of the salt cavern gas storage is increased.

[0005] In order to solve the above technical problems, the technical solution proposed by the present invention is:

[0006] A pipe column for gas injection and brine removal in a salt cavern gas storage includes a gas injection pipe, a brine removal pipe and a release handle. The gas injection pipe is sleeved outside the brine removal pipe, and the release handle is placed inside the brine removal pipe. A telescopic involute-shaped trumpet tube is provided at one end of the brine removal pipe near the release handle. When the telescopic involute-shaped trumpet tube is lowered into the gas injection pipe, the telescopic involute-shaped trumpet tube can maintain a contracted state to form a cylindrical tube, and can be opened into a trumpet tube when the telescopic involute-shaped trumpet tube passes through the gas injection pipe and enters the salt cavity.

[0007] According to the salt cavern gas storage gas injection and brine removal process pipe column of the present invention, when the bell pipe at the lower end of the brine removal pipe column is lowered to the outside of the gas injection pipe column, the bell pipe will open to form a bell mouth at the lower end of the brine removal pipe column. Through the effect of the bell mouth, the bottom pipe diameter of the brine removal pipe column is increased, and under the same brine removal flow rate condition, the pipe mouth flow rate is effectively reduced, and the safety distance between the gas-brine interface and the brine removal pipe mouth that ensures that the natural gas is not carried out is reduced, so that the allowable gas-brine interface position becomes deeper, which is conducive to the discharge of more brine volume and the increase of the effective volume of the gas storage.

[0008] For the above technical solution, further improvements as described below can be made.

[0009] According to the salt cavern gas storage gas injection and brine removal process pipe column of the present invention, in a preferred embodiment, the telescopic involute flared tube is made of rigid materials and flexible materials arranged alternately, and a load-bearing component and an elastic support device are respectively provided on the outer side and the inner side of the telescopic involute flared tube. When the telescopic involute flared tube is lowered into the gas injection pipe, the load-bearing component applies pressure to the telescopic involute flared tube to cause it to shrink, and when the telescopic involute flared tube passes through the gas injection pipe and enters the salt cavity, the elastic force applied by the elastic support device causes it to open.

[0010] During the lowering of the bell tube at the lower end of the gas injection and brine removal column of the present invention into the gas injection column, the bell tube remains in a contracted state under the action of the elastic support devices and the load-bearing devices inside and outside the bell tube, thereby ensuring the lowering of the brine removal column. When the bell tube at the lower end of the brine removal column passes through the gas injection pipe and enters the salt cavity, since the bell tube is composed of a rigid material and a flexible material, the load-bearing device outside the bell tube loses the force of the middle tube, and the bell tube opens under the action of the internal elastic support device, so the entire working process is stable and reliable, and the operation is convenient.

[0011] Specifically, in a preferred embodiment, the elastic support device includes an inner roller structure arranged at the end of the brine discharge pipe, the inner roller structure is arranged in a symmetrical form with the axis of the telescopic involute flare pipe as the center, and an elastic support component is provided between the inner roller structure and the end of the brine discharge pipe so that the inner roller structure can slide along the inner surface of the telescopic involute flare pipe.

[0012] The elastic support device of the above structural form can realize the contraction and expansion of the trumpet tube extremely conveniently, and has a simple structure and is easy to process and manufacture. In addition, the roller structure does not cause wear to the inner side of the trumpet tube, thereby effectively improving the service life of the trumpet tube.

[0013] Further, in a preferred embodiment, the inner roller structure and the elastic support component are both arranged at the end of the brine discharge pipe through the support component.

[0014] The entire elastic support device is arranged at the end of the brine discharge pipe through the support component, which can effectively ensure the structural stability of the entire steam injection and brine discharge process pipe column.

[0015] Specifically, in a preferred embodiment, the support component includes two intersecting support beams and a support node.

[0016] The supporting component of the above structural form has a simple structure, is stable and reliable, is easy to process and has low cost.

[0017] Specifically, in a preferred embodiment, the elastic supporting component includes a spring.

[0018] Conventional springs are used as elastic supporting components, which have strong operability, are easy to assemble and have low cost.

[0019] Specifically, in a preferred embodiment, the load-bearing component includes an outer roller structure.

[0020] The load-bearing component is also configured as a roller structure, which can also effectively avoid wear on the outer side of the trumpet tube, thereby further increasing the service life of the trumpet tube.

[0021] Further, in a preferred embodiment, the outer roller structures are evenly spaced and arranged on the outer side of the telescopic involute horn.

[0022] The evenly spaced outer roller structure can effectively ensure that the trumpet tube is evenly stressed during the lowering of the gas injection tube, and the contraction process is stable and reliable.

[0023] Specifically, in a preferred embodiment, the rigid material includes a stainless steel rod.

[0024] The stainless steel rod can play a good supporting role and ensure the structural strength of the entire trumpet tube during the contraction and expansion process.

[0025] Specifically, in a preferred embodiment, the flexible material includes rubber.

[0026] The combination of rubber material and stainless steel rod can not only improve the structural strength of the entire trumpet tube, but also realize the contraction and expansion of the trumpet tube.

[0027] Compared with the prior art, the advantages of the present invention are: the diameter of the bottom of the brine discharge pipe column is increased, and under the condition of a constant brine discharge flow rate, the flow velocity at the pipe mouth is effectively reduced, and the safety distance between the gas-brine interface that ensures that the natural gas is not carried out and the brine discharge pipe mouth is reduced, so that the allowable gas-brine interface position becomes deeper, which is conducive to discharging more brine volume and increasing the effective volume of the gas storage reservoir. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The present invention will be described in more detail below based on embodiments and with reference to the accompanying drawings, wherein:

[0029] Figure 1 The contraction state of the gas injection and brine removal process pipe string of the salt cavern gas storage in the embodiment of the present invention is schematically shown;

[0030] Figure 2 The schematic diagram shows the open state of the gas injection and brine removal process column of the salt cavern gas storage in the embodiment of the present invention;

[0031] Figure 3 The structure of the trumpet tube according to the embodiment of the present invention is schematically shown;

[0032] Figure 4 The top view structure of the supporting component of the embodiment of the present invention is schematically shown;

[0033] Figure 5 The schematic diagram shows the vortex flow near the brine exhaust pipe outlet of an embodiment of the present invention. DETAILED DESCRIPTION

[0034] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, but the protection scope of the present invention is not limited thereby.

[0035] Figure 1 The contraction state of the gas injection and brine removal process pipe string 10 of the salt cavern gas storage in the embodiment of the present invention is schematically shown. Figure 2 The open state of the gas injection and brine removal process pipe column 10 of the salt cavern gas storage in the embodiment of the present invention is schematically shown. Figure 3 The structure of the bell tube 4 according to the embodiment of the present invention is schematically shown. Figure 4 The top view structure of the supporting component 7 according to the embodiment of the present invention is schematically shown. Figure 5 The schematic diagram shows the vortex flow near the brine exhaust pipe outlet of an embodiment of the present invention.

[0036] like Figure 1 and Figure 2 As shown, the salt cavern gas storage gas injection and brine removal process column 10 of the embodiment of the present invention comprises a gas injection pipe 1, a brine discharge pipe 2 and a release handle 3. Among them, the gas injection pipe 1 is sleeved outside the brine discharge pipe 2, and the release handle 3 is placed inside the brine discharge pipe 2. A telescopic involute flared tube 4 is provided at one end of the brine discharge pipe 2 close to the release handle 3. When the gas injection pipe 1 is lowered, the telescopic involute flared tube 4 can maintain a contracted state to form a cylindrical tube, and when the telescopic involute flared tube 4 passes through the gas injection pipe 1 and enters the salt cavity, it can be opened into a flared tube.

[0037] According to the salt cavern gas storage gas injection and brine removal process pipe column of the embodiment of the present invention, when the bell pipe at the lower end of the brine removal pipe column is lowered to the outside of the gas injection pipe column, the bell pipe will open to form a bell mouth at the lower end of the brine removal pipe column. Through the effect of the bell mouth, the bottom pipe diameter of the brine removal pipe column is increased, and under the same brine removal flow rate condition, the pipe mouth flow rate is effectively reduced, and the safety distance between the gas-brine interface and the brine removal pipe mouth that ensures that the natural gas is not carried out is reduced, so that the allowable gas-brine interface position becomes deeper, which is conducive to the discharge of more brine volume and the increase of the effective volume of the gas storage.

[0038] like Figures 1 to 3 As shown, specifically, in this embodiment, the telescopic involute horn tube 4 is made of rigid material 41 and flexible material 42 arranged alternately, and a load-bearing component 5 and an elastic support device 6 are respectively provided on the outer side and the inner side of the telescopic involute horn tube 4. When the telescopic involute horn tube is lowered into the gas injection pipe, the load-bearing component applies pressure to the telescopic involute horn tube to make it shrink, and when the telescopic involute horn tube passes through the gas injection pipe and enters the salt cavity, the elastic force applied by the elastic support device makes it open. According to the embodiment of the present invention, during the lower end horn tube of the gas injection and brine removal column is lowered into the gas injection column, under the action of the elastic support devices and the load-bearing devices inside and outside the horn tube, the horn tube remains in a contracted state to ensure the lowering of the brine removal column. When the horn tube at the lower end of the brine removal column passes through the gas injection pipe and enters the salt cavity, since the horn tube is composed of rigid material and flexible material, the load-bearing device outside the horn tube loses the force of the middle tube, and the horn tube opens under the force of the internal elastic support device, and the whole working process is stable and reliable, and the operation is convenient.

[0039] Specifically, in this embodiment, the rigid material includes a stainless steel rod. The stainless steel rod can play a good supporting role and ensure the structural strength of the entire trumpet tube during the contraction and expansion process. Preferably, in this embodiment, the flexible material includes rubber. The rubber material and the stainless steel rod can not only well improve the structural strength of the entire trumpet tube, but also well realize the contraction and expansion of the trumpet tube.

[0040] like Figure 1 and Figure 2 As shown, specifically, in this embodiment, the elastic support device 6 includes an inner roller structure 61 arranged at the end of the brine discharge pipe 2, and the inner roller structure 61 is arranged in a symmetrical form with the axis of the telescopic involute horn tube as the center. An elastic support component 62 is provided between the inner roller structure 61 and the end of the brine discharge pipe 2 so that the inner roller structure 61 can slide along the inner side surface of the telescopic involute horn tube 4. The elastic support device of the above structural form can realize the contraction and opening of the horn tube extremely conveniently, and has a simple structure and is easy to process and manufacture. In addition, the roller structure will not cause wear to the inner side surface of the horn tube, thereby effectively improving the service life of the horn tube.

[0041] Furthermore, in this embodiment, the inner roller structure 61 and the elastic support component 62 are arranged at the end of the brine discharge pipe 2 through the support component 7. The entire elastic support device is arranged at the end of the brine discharge pipe through the support component, which can effectively ensure the structural stability of the entire steam injection and brine discharge process string. Specifically, Figure 4 As shown, in this embodiment, the support component 7 includes two intersecting support beams 71 and a support node 72. The support component of the above structural form has a simple structure, is stable and reliable, is easy to process, and has low cost. Figure 1 and Figure 2 As shown, in this embodiment, the elastic support member 62 includes a spring. Using a conventional spring as the elastic support member has strong operability, is easy to assemble, and has low cost.

[0042] Specifically, Figure 1 and Figure 2 As shown, in this embodiment, the load-bearing component 5 includes an external roller structure. The load-bearing component is also set as a roller structure, which can also effectively avoid wear on the outer side of the trumpet tube, thereby further improving the service life of the trumpet tube. Further, in this embodiment, the external roller structure is evenly spaced and arranged on the outer side of the telescopic involute trumpet tube 4. Through the evenly spaced external roller structure, it can be effectively ensured that the trumpet tube is evenly stressed during the lowering of the gas injection pipe, and the contraction process is stable and reliable.

[0043] The effect of the gas injection and brine removal process column of the embodiment of the present invention is verified by a specific test example:

[0044] During the process of gas injection and brine removal, due to the large cavity diameter, which can generally reach tens of meters, and the small diameter of the brine removal pipe column, the liquid level in the solution cavity drops slowly, and the gas-brine interface drops in a basically laminar manner. As the brine removal proceeds, the distance between the gas-brine interface and the brine removal pipe port gradually decreases, and the cavity bottom diameter is also small, which may form a vortex at the brine removal pipe port, causing the natural gas to be carried out.

[0045] like Figure 5 As shown, the potential vortex flow field is an irrotational flow field, the Bernoulli equation holds true for the entire flow field, and the total energy of the fluid element at two points at any height is conserved. Assume that the horizontal boundary asymptote of the free surface is z=z0, and the infinite point of the asymptote is related to any point on the free surface by

[0046]

[0047] Where: v is the fluid flow velocity at the calculation position; z s is the depth of the liquid column at the calculation position; p sis the pressure exerted on the fluid; v0 is the velocity of the fluid flow at the gas-halogen interface; z0 is the depth of the liquid column at the gas-halogen interface, which is taken as 0; p0 is the pressure exerted on the fluid at the gas-halogen interface; r is the radial distance between the gas-halogen interface and the center of the brine exhaust pipe.

[0048] On the horizontal boundary, r0→∞, v0=c / r0→0; and on the free surface, p s =p0, from the above formula we can get

[0049]

[0050] Substituting v = C / r into the above formula, we can get the equation of the free surface as follows: The equation of the rotation hyperbola is

[0051]

[0052] Considering that the cross-sectional area of ​​the dissolution cavity is much smaller than that of the brine drainage column, the influence of the falling speed of the gas-brine interface can be ignored. The critical distance between the brine drainage pipe port and the gas-brine interface can be obtained by using the above calculation formula:

[0053]

[0054] Where: ΔH is the distance between the brine discharge pipe and the gas-brine interface, ΔH = z s -z0.

[0055] Considering the diameter of the pipe column used in the current gas injection and brine removal process, the distance between the brine removal pipe mouth and the gas-brine interface under different brine removal rates can be calculated. As the brine removal rate increases, the critical distance between the brine removal pipe column and the gas-brine interface increases.

[0056] During the lowering of the bell tube of the gas injection and brine removal column into the gas injection column, the bell tube remains in a contracted state under the action of the tube wheels inside and outside the bell tube, thereby ensuring the lowering of the brine removal column. When the bell tube at the lower end of the brine removal column passes through the gas injection pipe and enters the salt cavity, since the bell tube is composed of rigid material and flexible material, the roller outside the bell tube loses the force of the middle tube, and the bell tube opens under the action of the spring and roller inside the tube.

[0057] Under the same brine discharge flow conditions, by using a bell-mouth process column, the diameter of the lower end of the brine discharge column will increase a lot, the brine flow rate will be much lower, and the allowable distance between the brine discharge column and the gas-brine interface will be much smaller. Under the condition that the brine discharge column is lowered to a certain depth and the natural gas is not carried by the column, the allowable gas-brine interface position is deeper, which is conducive to the discharge of more brine volume.

[0058] According to the above embodiments, it can be seen that the salt cavern gas storage gas injection and brine removal process pipe column involved in the present invention increases the bottom pipe diameter of the brine removal pipe column, effectively reduces the pipe mouth flow rate under the condition of a certain brine removal flow rate, and reduces the safety distance between the gas-brine interface that ensures that the natural gas is not carried out and the brine removal pipe mouth, so that the allowable gas-brine interface position becomes deeper, which is conducive to the discharge of more brine volume and increasing the effective volume of the gas storage.

[0059] Although the present invention has been described with reference to preferred embodiments, various modifications may be made thereto and parts thereof may be replaced by equivalents without departing from the scope of the present invention. In particular, the various technical features mentioned in the various embodiments may be combined in any manner as long as there are no structural conflicts. The present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A gas injection and brine removal process column for a salt cavern gas storage, characterized in that: It includes air injection pipe, brine discharge pipe and release handle; among them, The air injection pipe is sleeved outside the brine discharge pipe, and the release handle is placed inside the brine discharge pipe; A telescopic involute-shaped trumpet tube is provided on one end of the brine discharge pipe close to the release handle. When the telescopic involute-shaped trumpet tube is lowered into the gas injection pipe, the telescopic involute-shaped trumpet tube can remain in a contracted state to form a cylindrical tube, and can be expanded into a trumpet tube when the telescopic involute-shaped trumpet tube passes through the gas injection pipe and enters the salt cavity; The telescopic involute horn tube is made of rigid materials and flexible materials arranged alternately, and a load-bearing component and an elastic supporting device are respectively provided on the outer side surface and the inner side surface of the telescopic involute horn tube; When the telescopic involute flared tube is lowered into the gas injection pipe, pressure is applied to the involute flared tube by the load-bearing component to cause it to contract, and when the telescopic involute flared tube passes through the gas injection pipe and enters the salt cavity, the elastic force applied by the elastic support device causes it to open; The elastic support device includes an inner roller structure arranged at the end of the brine discharge pipe, and the inner roller structure is arranged in a symmetrical manner with the axis of the telescopic involute flared tube as the center. An elastic support component is provided between the inner roller structure and the end of the brine discharge pipe so that the inner roller structure can slide along the inner side surface of the telescopic involute flared tube.

2. The gas injection and brine removal process column for salt cavern gas storage according to claim 1 is characterized in that: The inner roller structure and the elastic support component are both arranged at the end of the brine discharge pipe through a support component.

3. The gas injection and brine removal process column for salt cavern gas storage according to claim 2 is characterized in that: The supporting component includes two intersecting supporting beams and a supporting node.

4. The gas injection and brine removal process column for a salt cavern gas storage according to any one of claims 1 to 3, characterized in that: The elastic supporting member includes a spring.

5. The gas injection and brine removal process column for salt cavern gas storage according to any one of claims 1 to 3, characterized in that: The load-bearing component includes an outer roller structure.

6. The gas injection and brine removal process column for salt cavern gas storage according to claim 5, characterized in that: The outer roller structures are evenly spaced and arranged on the outer side of the telescopic involute horn.

7. The gas injection and brine removal process column for a salt cavern gas storage according to any one of claims 1 to 3, characterized in that: The rigid material comprises a stainless steel rod.

8. The gas injection and brine removal process column for a salt cavern gas storage according to any one of claims 1 to 3, characterized in that: The flexible material includes rubber skin.

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