Water-soluble cavity-making system and method for salt-cavern gas storage

Abstract

The invention discloses a water-soluble cavity making system and method for a salt cavern gas storage.The water-soluble cavity making system comprises a first treatment device arranged on the ground and used for conducting primary treatment on cavity making water and conveying the treated cavity making water to a wellhead, and the first treatment device is selected from one or more of a heating device, a magnetizing device and a dosing device; and the wellhead conveying device is used for dissolving the salt cavity by using the treated cavity making water in a positive circulation or reverse circulation mode. According to the method, the permeability and fluidity of cavity fluid and the dissolution promoting performance of salt rocks can be enhanced, the dissolution speed of the salt rocks is increased, and the water-soluble cavity making efficiency and economical efficiency are effectively improved.

Description

Technical Field

[0001] The invention relates to the technical field of salt cavern gas storage construction, and in particular to a water-soluble cavity making system and method for salt cavern gas storage. Background Art

[0002] Salt cavern gas storage is one of the main types of underground gas storage at home and abroad. Water dissolution cavity creation is the main method of salt cavern gas storage construction at home and abroad. The hydraulic cavity creation is carried out through the circulation of liquid in inner and outer pipes. The factors affecting the speed of water dissolution cavity creation can be divided into internal factors and external factors. The internal factors include the water solubility of salt minerals, the grade of salt ore, the composition of salt ore, etc. The external factors mainly include the circulation method, water injection displacement, casing and cavity creation string, etc. In addition, it is also affected by factors such as the inclination of the dissolution surface and the temperature of the salt rock layer.

[0003] In order to increase the speed of cavity construction, some research and practical work has been done at home and abroad, mainly using large wellbore cavity construction, increasing water injection displacement, and optimizing cavity construction parameters.

[0004] In the existing patent CN110388231A "A salt cavern gas storage cavity making device and method", a salt cavern gas storage cavity making device and method are involved, which belongs to the field of natural gas storage. The method includes: determining the upper interface and the lower interface of the cavity, drilling a vertical well, fixing the casing in the vertical well, so that the bottom end of the casing is below the upper salt surface and above the upper interface. Install the wellhead equipment, and lower the cavity making pipe column into the vertical well through the wellhead equipment and the casing, so that the bottom end of the cavity making pipe column is below the upper interface and above the lower interface. Inject a preset amount of nitrogen into the vertical well through the gas pipeline, and inject water into the vertical well through the water injection pipe. The salt layer is dissolved in the water, and the brine is discharged through the brine discharge pipe by controlling the opening and closing of the valve. After the preset water injection time, the cavity is completed. This invention can be used to create a cavern in a salt layer to obtain a salt cavern gas storage reservoir. The water injection and salt discharge process includes both positive circulation and reverse circulation methods to meet different production needs at different cavern creation periods. In addition, by using nitrogen as a dissolution inhibitor, the cost is low and environmental pollution is avoided.

[0005] In the existing patent CN114033492A "A rapid cavity dissolution method and cavity dissolution equipment for a salt cavern gas storage reservoir", a rapid cavity dissolution method and cavity dissolution equipment for a salt cavern gas storage reservoir are disclosed, which are used to drill a well body of a preset depth from the ground to the underground salt layer, and excavate the salt cavern gas storage reservoir circumferentially at the preset depth position of the well body. The cavity dissolution method includes: firstly lowering a cavity making main pipe composed of a double-layer tube of an outer tube and a central tube to a preset height position in the well body from the bottom of the well; injecting a protective liquid into the bottom of the well through the central tube; then injecting fresh water into the well body for the first time to obtain a cavity of a first preset size; and injecting fresh water into the well body for the second time to obtain a cavity of a second preset size; while injecting fresh water into the well body for the first and second times to make a cavity, a jetting tool and a cavity making tool with a hose are set to assist in cavity making to increase the cavity making efficiency. Finally, the cavity of the second preset size is subjected to size detection and sealing leak detection test to obtain a salt cavern gas storage reservoir. The invention can be widely used in the field of underground energy storage technology.

[0006] In addition, the existing literature technology "Research and Application of Layered Salt Layer Cavity Speed-up Technology [J]" introduces that my country's salt cavern gas storage is built on layered salt layers. The salt rock has low grade and many interlayers, and the cavity speed is slow. It takes about 4 years to build a 200,000 cubic meter cavity, which cannot meet the needs of my country's underground gas storage construction. It is urgent to seek new cavity-making methods to speed up the cavity-making speed of multi-interlayer salt cavern gas storage. The paper analyzes the cavity dissolution mechanism of salt cavern gas storage; proposes four cavity-making speed-up methods such as reaming, rapid tool dissolution, large borehole cavity making, and double borehole cavity making, analyzes and evaluates the field application effects of reaming and rapid tool dissolution, and proposes large borehole cavity making and double borehole cavity making technologies suitable for the construction of multi-interlayer salt cavern gas storage in my country. Research shows that rapid cavity-making technology is of great significance for shortening the construction period of salt caverns in my country, saving construction funds, and improving construction efficiency.

[0007] In summary, in terms of improving the speed of cavern construction in salt cavern gas storage, the existing technologies mainly focus on expanding the borehole, using large boreholes to create caverns, increasing the water injection rate, and special cavern construction methods such as double-well cavern construction; but few involve solutions to increase the speed of cavern construction from the perspective of cavity fluid. Summary of the invention

[0008] The purpose of the present invention is to provide a method for enhancing the permeability and flowability of cavity water by treating the cavity fluid, so as to achieve the purpose of increasing the cavity building speed.

[0009] In order to solve the above technical problems, an embodiment of the present invention provides a water-dissolving cavitation system for a salt cavern gas storage, comprising: a first treatment device arranged on the ground, which is used for preliminary treatment of cavitation water, and the first treatment device is a first device selected from a heating device, a magnetization device and a dosing device; a wellhead conveying device, which is connected to the first treatment device, and is used to use the treated cavitation water to dissolve the salt cavity in a positive circulation or reverse circulation manner.

[0010] Preferably, the water-soluble cavity-making system further comprises: a second processing device, which is a second device selected from a heating device, a magnetizing device and a dosing device.

[0011] Preferably, the two processing devices are a heating device and a magnetizing device, respectively, wherein the magnetizing device is arranged between the heating device and the wellhead conveying device.

[0012] Preferably, the two treatment devices are a heating device and a dosing device, wherein the heating device and the dosing device are respectively connected to the wellhead conveying device, and the dosing device is used to add salt solvent to the cavity making water heated by the heating device and transported to the wellhead conveying device.

[0013] Preferably, the two treatment devices are respectively a magnetizing device and a dosing device, wherein the magnetizing device and the dosing device are respectively connected to the wellhead conveying device, and the dosing device is used to add salt solvent to the cavity making water magnetized by the magnetizing device and transported to the wellhead conveying device.

[0014] Preferably, the water-soluble cavity making system also includes: a third treatment device, which is a third device selected from a heating device, a magnetizing device and a dosing device, wherein the magnetizing device is arranged between the heating device and the wellhead conveying device, and the dosing device is connected to the wellhead conveying device.

[0015] Preferably, the water-soluble cavity making system also includes: at least one swirl short section connected to the bottom of the cavity making inner pipe column, the setting depth of the at least one swirl short section corresponds to the bottom of the cavity making outer pipe column and is close to the top of the salt cavity, wherein the swirl short section is configured to form a swirl when the cavity making water flows through the swirl short section in a reverse circulation cavity making manner.

[0016] Preferably, the swirl nipple comprises: a central tube with a central through hole formed inside, the inner diameter of the central through hole being the same as the inner diameter of the cavity-making inner tube column; and a steel belt fixed on the central tube in a spirally wound manner, so that the cavity-making water rotates along the steel belt around the central tube to generate a swirl.

[0017] Preferably, the dosing device includes: a first skid-mounted platform; a liquid storage tank and an injection pump installed on the first skid-mounted platform, the liquid storage tank is used to hold medicine, the injection pump is connected to the liquid storage tank and is used to control the injection amount and / or injection speed of the medicine; a liquid level monitor arranged in the liquid storage tank; and a first gate arranged at the outlet end of the injection pump.

[0018] Preferably, the magnetization device comprises: a second skid-mounted platform; a plurality of magnetization devices mounted on the second skid-mounted platform; a conveying pipe extending through each of the magnetization devices, wherein an electromagnetic coil wound around the conveying pipe is disposed inside each of the magnetization devices; and a second gate, wherein the magnetization device is connected to the wellhead conveying device via the second gate.

[0019] Preferably, the wellhead conveying device is constructed to adopt a positive circulation method in the initial bottom pit formation stage and a reverse circulation method for cavity dissolution in the cavity formation stage; the heating device heats the cavity formation water to at least 50°C; the cavity formation water is fresh water or low-concentration brine.

[0020] On the other hand, an embodiment of the present invention provides a water-dissolving cavitation method for a salt cavern gas storage, comprising: performing preliminary treatment on cavitation water by a first treatment device arranged on the ground, wherein the preliminary treatment is selected from one of heating, electromagnetic treatment and adding a reagent; and using the treated cavitation water to dissolve the salt cavity in a positive circulation or reverse circulation cavitation manner.

[0021] Preferably, the water-soluble cavity-forming method is implemented by using the water-soluble cavity-forming system described above.

[0022] Compared with the prior art, one or more embodiments of the above scheme may have the following advantages or beneficial effects:

[0023] The present invention proposes a water-soluble cavity making system and method for salt cavern gas storage. When the present invention is used for water-soluble cavity making, the temperature of the fluid in the cavity has a great influence on the dissolution rate. As the temperature rises, the dissolution rate of rock salt gradually increases in an exponential relationship. The temperature of the water injected into the cavity can be increased by a heating device; magnetized water can reduce the surface tension coefficient and viscosity coefficient of water, enhance the permeability and fluidity of water, and increase the dissolution rate of salt rock by more than 20%, so the salt rock dissolution capacity is improved by a magnetizing device; the salt promoting agent is continuously added by a dosing device to achieve the purpose of promoting the dissolution of salt minerals; the water injected into the cavity passes through a downhole spiral device to increase the vortex intensity of the fluid in the cavity, change the inclination angle of the dissolution surface, and achieve the purpose of promoting the dissolution of salt rock. Therefore, the present invention can improve the temperature, magnetism and swirl strength of the injected water during water-soluble cavitation by using an integrated high-efficiency cavitation system composed of a dosing device, a heating device, a magnetizing device and a downhole spiral tool, enhance the permeability and fluidity of the cavitation fluid and the solubility of the salt rock, accelerate the dissolution rate of the salt rock, effectively improve the efficiency and economy of water-soluble cavitation, shorten the construction time of the gas storage, and greatly reduce the construction cost of the gas storage. In addition, salt cavern gas storage is one of the main types of gas storage, and its number is second only to the depleted gas reservoir type gas storage. The large-scale application of the present invention can greatly improve the efficiency of storage construction, and has broad application prospects.

[0024] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0026] Figure 1 This is a first overall structural schematic diagram of a water-soluble cavity-making system for a salt cavern gas storage according to an embodiment of the present application.

[0027] Figure 2 This is a second overall structural schematic diagram of the water-soluble cavity making system for salt cavern gas storage according to an embodiment of the present application.

[0028] Figure 3 This is a third overall structural schematic diagram of the water-soluble cavity making system for salt cavern gas storage according to an embodiment of the present application.

[0029] Figure 4 This is a schematic diagram of the specific structure of the dosing device in the water-soluble cavity making system for the salt cavern gas storage according to an embodiment of the present application.

[0030] Figure 5This is a schematic diagram of the specific structure of the magnetization device in the water-soluble cavity-making system for the salt cavern gas storage according to an embodiment of the present application.

[0031] Figure 6 This is a schematic diagram of the specific structure of a cyclone short section in a water-soluble cavity-making system for a salt cavern gas storage according to an embodiment of the present application.

[0032] Figure 7 Schematic diagram of the overall steps of the water-soluble cavity making method for salt cavern gas storage according to an embodiment of the present application. DETAILED DESCRIPTION

[0033] The following will describe the implementation methods of the present invention in detail with reference to the accompanying drawings and embodiments, so that the implementation process of how the present invention applies technical means to solve technical problems and achieve technical effects can be fully understood and implemented accordingly. It should be noted that as long as there is no conflict, the various embodiments of the present invention and the various features in the embodiments can be combined with each other, and the technical solutions formed are all within the protection scope of the present invention.

[0034] In addition, the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions. Also, although a logical sequence is shown in the flowchart, in some cases, the steps shown or described can be performed in a sequence different from that here.

[0035] The terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments. Unless the context clearly indicates otherwise, the singular forms "one", "one" and "item" used herein are also intended to include plural numbers. It should also be understood that the terms "include" and / or "comprise" used herein specify the existence of stated features, integers, steps, operations, units and / or components, without excluding the existence or addition of one or more other features, integers, steps, operations, units, components and / or combinations thereof.

[0036] In order to solve one or more technical problems in the above-mentioned background technology, the embodiment of the present application proposes a water-soluble cavity making system and method for salt cavern gas storage. The present invention adopts a positive and reverse circulation fluid cavity making method, and through the design of an integrated cavity making system composed of a heating device, a heating device, a magnetizing device, an automatic dosing device and a downhole spiral tool, it can enhance the permeability and fluidity of the cavity water to varying degrees, improve the vortex strength of the fluid in the cavity to varying degrees, accelerate the dissolution rate of salt rock, effectively improve the efficiency and economy of water-soluble cavity making, shorten the construction time of the gas storage, and reduce the construction cost of the gas storage.

[0037] Figure 1 This is a schematic diagram of the first overall structure of the water-soluble cavity-making system for salt cavern gas storage in the embodiment of the present application. Figure 1, an example of the overall structure of the water-soluble cavity-making system described in an embodiment of the present invention is described.

[0038] like Figure 1 As shown, the water-soluble cavitation system described in the embodiment of the present invention at least includes: a wellhead conveying device 1 and a first treatment device A. The first treatment device A is arranged on the ground. The first treatment device A is used to preliminarily treat the cavitation water to be transported, and transport the treated cavitation water to the wellhead. The first treatment device A is connected to the wellhead conveying device 1. The wellhead conveying device 1 is used to use the treated cavitation water to dissolve the salt cavity in a positive circulation or reverse circulation manner.

[0039] In the embodiment of the present invention, the first processing device A is a first device selected from the heating device 4, the magnetizing device 3 and the dosing device 2. It should be noted that the selection of the first processing device A is a non-sequential and non-specified selection, which can be understood as an arbitrary selection. In other words, the first processing device A is selected from one of a plurality of alternative devices. The plurality of alternative devices include but are not limited to: the dosing device 2, the magnetizing device 3 and the heating device 4.

[0040] In one embodiment, the cavity creation water described in the embodiment of the present invention is fresh water or low-concentration brine.

[0041] In one embodiment, the wellhead conveying device 1 is configured to adopt a positive circulation method in the initial bottom pit formation stage and a reverse circulation method in the cavity formation stage to dissolve the cavity.

[0042] When the first processing device A is a heating device 4 (see Figure 3 ), the heating device 4 is connected to the wellhead conveying device 1 through the ground water delivery pipe. The heating device 4 is used to heat the cavity water and deliver the heated cavity water to the wellhead conveying device 1 at the wellhead. The wellhead conveying device 1 is used to dissolve the salt cavity using the heated cavity water in a positive circulation or reverse circulation manner.

[0043] In one embodiment, the heating device 4 heats the cavity creation water to at least 50°C.

[0044] After the cavity water is transported to the heating device 4, the heating device 4 heats the transported cavity water. After the heating is completed, the heated cavity water is transported to the wellhead transport device 1 through the ground water pipe, so that the wellhead transport device 1 transports the high-temperature cavity water to the underground salt cavity. Figure 3 , the high-temperature cavity-forming water enters the salt cavity 11 through the cavity-forming inner pipe string 7; the high-temperature cavity-forming water after the cavity is dissolved returns through the annulus between the cavity-forming inner pipe string 7 and the cavity-forming outer pipe string 6. In the reverse circulation process, refer to Figure 3The high-temperature cavity-forming water enters the salt cavity 11 through the annulus between the cavity-forming inner pipe string 7 and the cavity-forming outer pipe string 6; the high-temperature cavity-forming water after the cavity is dissolved returns through the cavity-forming inner pipe string 7.

[0045] Fresh water or low-concentration brine used for cavity building enters the heating device 4 for heating and temperature rise, at least to above 50 degrees, and then enters the wellhead through the connecting pipeline. When water-soluble cavity building is carried out, the fluid temperature in the salt cavity has a great influence on the dissolution rate. As the temperature rises, the dissolution rate of salt rock gradually increases, showing an exponential relationship. In this way, the temperature of the water injected into the cavity building can be greatly increased by the heating device 4, so as to achieve rapid dissolution of salt rock and improve the cavity building speed.

[0046] When the first processing device A is a magnetizing device 3 (see Figure 3 ), the magnetizing device 3 is connected to the wellhead conveying device 1 through the ground conveying pipe. The magnetizing device 3 is used to perform electromagnetic treatment on the cavitation water, and convey the cavitation water after the electromagnetic treatment to the wellhead conveying device 1 at the wellhead. The wellhead conveying device 1 is used to dissolve the salt cavity by using the cavitation water after the electromagnetic treatment in a positive circulation or reverse circulation manner.

[0047] When the cavity water is transported to the magnetizing device 3, the magnetizing device 3 magnetizes the transported cavity water, so that the magnetized cavity water is transported to the wellhead transport device 1 via the surface water transport pipe, so that the magnetized cavity water is transported to the underground salt cavity by the wellhead transport device 1. Figure 3 , the magnetized cavity water enters the salt cavity 11 through the cavity inner pipe string 7; the magnetized cavity water after the cavity is dissolved returns through the annulus between the cavity inner pipe string 7 and the cavity outer pipe string 6. In the reverse circulation process, refer to Figure 3 The magnetized cavity-forming water enters the salt cavity 11 through the annulus between the cavity-forming inner pipe string 7 and the cavity-forming outer pipe string 6; the magnetized cavity-forming water after the cavity is dissolved returns through the cavity-forming inner pipe string 7.

[0048] The magnetized water treated by the magnetizing device 3 can reduce the surface tension coefficient and viscosity coefficient of water, thereby enhancing the permeability and fluidity of the cavity-forming water. The magnetized water can increase the salt rock dissolution rate by more than 20% during the cavity dissolution process, thereby achieving the purpose of improving the dissolution capacity of the cavity-forming salt rock.

[0049] When the first treatment device A is a dosing device 2 (see Figure 3 ), the dosing device 2 is connected to the wellhead delivery device 1 through the ground delivery water pipe. The dosing device 2 is used to automatically add salt solvent to the cavity water to be delivered (for example, continuously or at a preset time interval), so that the wellhead delivery device 1 uses the cavity water mixed with the salt solvent to dissolve the salt cavity in a positive circulation or reverse circulation manner.

[0050] In the embodiments of the present invention, the salt solvent includes but is not limited to a salt promoting solvent and a salt auxiliary solvent.

[0051] When the cavity water is delivered to the wellhead delivery device 1, the dosing device 2 automatically adds salt solvent to the delivered cavity water continuously or at a preset time interval, so that the cavity water mixed with the salt solvent is delivered to the underground salt cavity by the wellhead delivery device 1. Figure 3 , the cavity-forming water mixed with salt solvent enters the salt cavity 11 through the cavity-forming inner pipe string 7; the cavity-forming water after dissolving the cavity returns through the annulus between the cavity-forming inner pipe string 7 and the cavity-forming outer pipe string 6. Figure 3 The cavity-forming water mixed with the salt solvent enters the salt cavity 11 through the annulus between the cavity-forming inner tubular column 7 and the cavity-forming outer tubular column 6 ; the cavity-forming water after the cavity is dissolved returns through the cavity-forming inner tubular column 7 .

[0052] The automatic dosing device 2 injects a salt solvent liquid containing a salt promoter, a salt co-solvent and the like into the wellbore through the wellhead 1, so that the salt solvent liquid merges with the cavity injection water and flows into the cavity together, thereby achieving the purpose of promoting the dissolution of salt minerals in the cavity.

[0053] Figure 2 This is a second overall structural diagram of the water-soluble cavity-making system for salt cavern gas storage in an embodiment of the present application. Figure 1 Based on the first overall structure example shown, Figure 2 As shown, the water-soluble cavity-making system described in the embodiment of the present invention also includes: a second processing device B.

[0054] The second treatment device is a second device selected from the heating device 4, the magnetizing device 3 and the dosing device 2. That is, the second treatment device B is one of the remaining alternative devices except the first treatment device A among all the alternative devices.

[0055] When the two selected processing devices A and B are respectively a heating device 4 and a magnetizing device 3, refer to Figure 3 , the magnetizing device 3 is arranged between the heating device 4 and the wellhead conveying device 1. The first end of the magnetizing device 3 is connected to the heating device 4 through the surface conveying water pipe, and the second end of the magnetizing device 3 is connected to the wellhead conveying device 1 through the surface conveying water pipe. At this time, the heating device 4 is used to heat the conveyed cavitation water; the magnetizing device 3 is used to magnetize the heated cavitation water, and convey the high-temperature magnetized cavitation water to the wellhead conveying device 1, so that the wellhead conveying device 1 uses the high-temperature magnetized cavitation water to dissolve the salt cavity.

[0056] When the two selected treatment devices A and B are respectively the heating device 4 and the dosing device 2, refer to Figure 3, the heating device 4 and the dosing device 2 are respectively connected to the wellhead conveying device 1. The heating device 4 is connected to the wellhead conveying device 1 through the ground conveying water pipe, and at the same time, the dosing device 2 is connected to the wellhead conveying device 1 through the ground conveying water pipe. At this time, the heating device 4 is used to heat the delivered cavity water; the dosing device 2 is used to automatically add salt solvent to the high-temperature cavity water heated by the heating device 4 and transported to the wellhead conveying device 1, so that the wellhead conveying device 1 uses a high-temperature fluid mixed with salt solvent to dissolve the salt cavity.

[0057] When the two selected processing devices A and B are respectively the magnetizing device 3 and the dosing device 2, refer to Figure 3 , the magnetizing device 3 and the dosing device 2 are respectively connected to the wellhead conveying device 1. The magnetizing device 3 is connected to the wellhead conveying device 1 through the ground conveying water pipe, and at the same time, the dosing device 2 is connected to the wellhead conveying device 1 through the ground conveying water pipe. At this time, the magnetizing device 3 is used to magnetize the cavity-making water to be transported, and transport the magnetized cavity-making water to the wellhead conveying device 1; the dosing device 2 is used to automatically add salt solvent to the magnetized cavity-making water magnetized by the magnetizing device 3 and transported to the wellhead conveying device 1, so that the wellhead conveying device 1 uses the fluid magnetized and mixed with the salt solvent to dissolve the salt cavity.

[0058] In this way, by superimposing any two treatment devices, a series of treatments on the cavity-forming water to be transmitted are completed, thereby achieving the accumulation of the dissolution-promoting effect of a single treatment device.

[0059] Figure 3 This is a third overall structural diagram of the water-soluble cavity-making system for salt cavern gas storage in an embodiment of the present application. Figure 2 Based on the second overall structure example shown, Figure 3 As shown, the water-soluble cavity-making system described in the embodiment of the present invention further includes: a third processing device (unnumbered).

[0060] The third treatment device is a third device selected from the heating device 4, the magnetizing device 3 and the dosing device 2. That is, the third treatment device is a device among all the candidate devices that has not been selected as the first and second treatment devices.

[0061] like Figure 3 As shown, the magnetizing device 3 is arranged between the heating device 4 and the wellhead conveying device 1, and the dosing device 2 is connected to the wellhead conveying device 1. At this time, the heating device 2 is used to heat the cavity-forming water to be conveyed; the magnetizing device 3 is used to magnetize the heated cavity-forming water, and convey the high-temperature magnetized cavity-forming water to the wellhead conveying device 1; the dosing device 2 is also used to automatically add salt solvent to the high-temperature magnetized cavity-forming water, so that the wellhead conveying device 1 uses the high-temperature magnetized and mixed rock solvent fluid to dissolve the salt cavity.

[0062] In the embodiment of the present invention, the cavity building circulation mode adopts two modes: positive circulation and reverse circulation. In the positive circulation mode, water flows into the salt cavity through the inner cavity building pipe string 7, and returns through the annulus between the outer cavity building pipe string 6 and the inner cavity building pipe string 7; in the reverse circulation mode, water flows into the cavity through the annulus between the outer cavity building pipe string 6 and the inner cavity building pipe string 7, and returns to the ground through the inner cavity building pipe string 7. The positive circulation mode is generally used in the initial stage of cavity building, and the reverse circulation mode is mostly used in the subsequent cavity building stage.

[0063] Positive circulation cavity making method: fresh water or low-concentration brine is heated by a heating device 4, and the fluid is magnetized when passing through a magnetizing device 3, and then enters a wellhead 1, at which a salt promoter can be added continuously or intermittently and automatically by an automatic dosing device 2, and the fluid of the high-temperature magnetized mixed salt promoter enters a salt cavity 11 through a cavity making inner pipe string 7; the high-concentration cavity making water after the cavity is dissolved is returned through the annulus between the cavity making outer pipe string 6 and the cavity making inner pipe string 7, so that the high-temperature magnetized water with the addition of the salt promoter can effectively improve the salt rock dissolution rate and the salt rock dissolution capacity.

[0064] Reverse circulation cavity making method: fresh water or low-concentration brine is heated by a heating device 4, and the fluid is magnetized when passing through a magnetizing device 3, and then enters a wellhead 1, at which a salt promoter can be added continuously or intermittently and automatically by an automatic dosing device 2, and the fluid of the high-temperature magnetized mixed salt promoter passes through the annulus between the cavity making outer pipe string 6 and the cavity making inner pipe string 7 and enters the salt cavity 11 for cavity dissolution; the high-concentration cavity making water after cavity dissolution is returned through the cavity making inner pipe string 7, and the high-temperature magnetized water with the addition of the salt promoter can effectively reduce the surface tension coefficient and viscosity coefficient of the dissolved salt water, enhance the permeability and fluidity of the water, increase the salt rock dissolution rate by more than 20%, effectively improve the salt rock dissolution capacity, and greatly improve the water-soluble cavity making efficiency and economy.

[0065] In this way, the embodiment of the present invention will process the cavity injection water to be transported through an integrated cavity making system composed of a dosing device, a heating device and an electromagnetic makeup device, and then carry out salt dissolving cavity making, which can accelerate the dissolution rate of salt rock and effectively improve the water-soluble cavity making efficiency.

[0066] Figure 4 This is a schematic diagram of the specific structure of the dosing device in the water-soluble cavity making system for the salt cavern gas storage in the embodiment of the present application. Figure 4 As shown, the dosing device 2 includes: a first skid-mounted platform 2-6, a liquid storage tank 2-4, a liquid level monitor 2-5, an injection pump 2-2 and a first gate 2-1. The liquid storage tank 2-4 and the injection pump 2-1 are installed on the first skid-mounted platform 2-6.

[0067] The liquid storage tank 2-4 is used to hold the pharmaceutical fluid. The liquid level monitor 2-5 is arranged in the liquid storage tank 2-4. The liquid level monitor 2-5 is used to automatically monitor the dynamic liquid level of the liquid storage tank 2-4. The injection pump 2-2 is connected to the outlet of the liquid storage tank 2-4 through the connecting pipe 2-3. The injection pump 2-2 is a variable frequency injection pump. The injection pump 2-2 is used to control the injection amount and / or injection speed of the pharmaceutical. The first gate 2-1 is arranged at the outlet end of the injection pump 2-2.

[0068] The automatic dosing device 2 can continuously or intermittently add salt solvents (pharmaceutical fluids) such as salt accelerators and salt co-solvents to promote the dissolution of salt minerals in the cavity.

[0069] In addition, in order to facilitate the installation and transportation of the automatic dosing device 2, the automatic dosing device 2 described in the present invention adopts a skid-mounted structure, and a series of equipment such as the liquid storage tank 2-4 and the injection pump 2-2 are all installed on the skid-mounted platform 2-6.

[0070] Figure 5 This is a schematic diagram of the specific structure of the magnetization device in the water-soluble cavity making system for the salt cavern gas storage in the embodiment of the present application. Figure 5 As shown, the magnetizing device 3 includes: a second skid-mounted platform 3-4, a plurality of magnetizing devices (3-1, 3-2, 3-3), an electromagnetic coil 3-5 and a second gate 3-7.

[0071] It should be noted that the embodiment of the present invention does not specifically limit the number of magnetizing devices configured in the magnetizing device 3, and those skilled in the art can configure the number according to the required magnetizing intensity.

[0072] In the embodiment of the present invention, the ground water delivery pipe 3-6 extends through each magnetizing device. In addition, an electromagnetic coil 3-5 wound around the water delivery pipe is arranged inside each magnetizing device.

[0073] The second gate 3-7 is arranged near the wellhead end of the plurality of cascaded magnetizing devices 3-1, 3-2, 3-3. The magnetizing device 3 is connected to the wellhead conveying device 1 via the second gate 3-7. Further, the second gate 3-7 is arranged at the second end position of the magnetizing device 3.

[0074] In addition, in order to facilitate the installation and transportation of the magnetizing device 3, the magnetizing device 3 described in the present invention adopts a skid-mounted structure, and all magnetizing equipment is installed on the skid-mounted platform 3-4.

[0075] In addition, in order to further improve the salt rock dissolution promoting effect in the cavity building stage, the water-soluble cavity building system described in the embodiment of the present invention further includes at least one cyclone short section 9.

[0076] like Figure 3As shown, at least one swirl short section 9 is arranged at the bottom of the inner cavity column 7. More specifically, the arrangement depth of at least one swirl short section 9 corresponds to the bottom of the outer cavity column 6 and is close to the top of the salt cavity (such as Figure 3 As shown, the top of the salt cavity is at the oil pad interface 10). Usually, at least one swirl nipple 9 is installed on the corresponding cavity-making inner pipe column 7 near the upper part of the cavity top.

[0077] The swirl nipple 9 is configured to form a swirl when the cavity-forming water flows through the swirl nipple 9 in a reverse circulation cavity-forming manner, so that after the swirl fluid (for example, high-temperature cavity-forming water, or magnetized cavity-forming water, or cavity-forming water mixed with a salt solvent, or high-temperature magnetized cavity-forming water, or high-temperature cavity-forming water mixed with a salt solvent, or magnetized cavity-forming water mixed with a salt solvent, or high-temperature magnetized cavity-forming water mixed with a salt solvent) enters the salt cavity, the effect of promoting the dissolution of salt rock can be further achieved.

[0078] In one embodiment, a plurality of swirl short sections 9 may be connected in series (cascaded) and then arranged on the cavity-making inner pipe column 7. That is, in the embodiment of the present invention, a plurality of swirl short sections 9 may be connected for use.

[0079] Figure 6 This is a schematic diagram of the specific structure of the swirl short section in the water-soluble cavity making system for the salt cavern gas storage in the embodiment of the present application. Figure 6 As shown, the swirl nipple 9 described in the embodiment of the present invention specifically includes: a central tube 9-3 and a steel belt 9-4.

[0080] A central through hole 9 - 2 is formed inside the central tube 9 - 3 , and the inner diameter of the central through hole 9 - 2 is the same as the inner diameter of the lumen-making tube column 7 .

[0081] like Figure 3 As shown, the steel belt 9-4 is a spiral steel belt. The steel belt 9-4 is fixed (e.g., welded) on the central tube 9-3 in a spiral winding manner, so that the cavity-making water rotates around the central tube 9-3 along the spiral steel belt to generate a vortex. Moreover, a certain gap is formed between the outer edge of the spiral steel belt 9-4 and the cavity-making outer pipe column 6, so that the cavity-making water fluid flows smoothly.

[0082] In addition, the swirl short section 9 also includes a connection buckle. The connection buckle includes: a connection female buckle 9-1 and a connection male buckle 9-5. The connection female buckle 9-1 and the connection male buckle 9-5 are respectively arranged at both ends of the central through hole 9-2, so as to realize the series connection between multiple swirl short sections 9 and the connection between the swirl short section 9 and the cavity-making inner pipe column 7.

[0083] When the cavity-making water injected into the dissolution cavity passes through the downhole cyclone short section 9, the fluid rotates along the spiral steel belt 9-4 on the spiral short section 9 around the central pipe 9-3, which produces a strong cyclone effect on the fluid. This fluid enters the salt cavity to dissolve the salt rock in the cavity, which can increase the fluid turbulence and cyclone intensity, and further achieve the purpose of promoting the dissolution of the salt rock in the cavity.

[0084] Example

[0085] During reverse circulation cavity making, fresh water or low-concentration brine is heated by a heating device 4, and the fluid is magnetized when passing through a magnetizing device 3, and then enters the wellhead 1. At the wellhead 1, a salt promoter can be added continuously or intermittently by an automatic dosing device 2. The fluid of the high-temperature magnetized mixed salt promoter passes through the annulus between the cavity making outer pipe string 6 and the cavity making inner pipe string 7, and then enters the swirl short section 9 to generate a swirl flow. Then the swirl fluid enters the salt cavity 11 for cavity dissolution; the cavity making water after cavity dissolution is returned through the cavity making inner pipe string 7. During positive circulation cavity making, fresh water or low-concentration brine is heated by a heating device 4, and the fluid is magnetized when passing through a magnetizing device 3, and then enters the wellhead 1. At the wellhead 1, a salt promoter can be added continuously or intermittently by an automatic dosing device 2, and the fluid of the high-temperature magnetized mixed salt promoter passes through the cavity making inner pipe string 7 and enters the salt cavity 11; the cavity making water after cavity dissolution is returned through the annulus between the cavity making outer pipe string 6 and the cavity making inner pipe string 7. High-temperature cyclonic magnetized water with the addition of salt promoter can effectively reduce the surface tension coefficient and viscosity coefficient of the dissolved salt water, enhance the permeability and fluidity of the water, increase the dissolution rate of salt rock by more than 20%, effectively improve the dissolution capacity of salt rock, and greatly improve the efficiency and economy of water-soluble cavity making.

[0086] On the other hand, based on the above water-soluble cavity making system, an embodiment of the present invention further provides a water-soluble cavity making method for salt cavern gas storage. The water-soluble cavity making method is implemented by the above water-soluble cavity making system.

[0087] Figure 7 This is a schematic diagram of the overall steps of the water-soluble cavity-making method for salt cavern gas storage in an embodiment of the present application. Figure 7 As shown, the water-soluble cavity-making method described in the embodiment of the present invention comprises at least the following steps:

[0088] Step S701, performing preliminary treatment on the cavitation water by a first treatment device arranged on the ground, wherein the preliminary treatment is selected from one of heating, electromagnetic treatment and adding a reagent;

[0089] Step S702, using the treated cavity-forming water to dissolve the salt cavity in a forward circulation or reverse circulation cavity-forming manner.

[0090] The present invention discloses a water-soluble cavity making system and method for salt cavern gas storage. When the present invention is used for water-soluble cavity making, the temperature of the fluid in the cavity has a great influence on the dissolution rate. As the temperature rises, the dissolution rate of rock salt gradually increases in an exponential relationship. The temperature of the water injected into the cavity can be increased by a heating device; magnetized water can reduce the surface tension coefficient and viscosity coefficient of water, enhance the permeability and fluidity of water, and increase the dissolution rate of salt rock by more than 20%, so the salt rock dissolution capacity is improved by a magnetizing device; the salt promoting agent is continuously added by a dosing device to achieve the purpose of promoting the dissolution of salt minerals; the water injected into the cavity passes through a downhole spiral device to increase the vortex strength of the fluid in the cavity, change the inclination angle of the dissolution surface, and achieve the purpose of promoting the dissolution of salt rock. Therefore, the present invention can improve the temperature, magnetism and swirl strength of the injected water during water-soluble cavitation by using an integrated high-efficiency cavitation system composed of a dosing device, a heating device, a magnetizing device and a downhole spiral tool, enhance the permeability and fluidity of the cavitation fluid and the solubility of the salt rock, accelerate the dissolution rate of the salt rock, effectively improve the efficiency and economy of water-soluble cavitation, shorten the construction time of the gas storage, and greatly reduce the construction cost of the gas storage. In addition, salt cavern gas storage is one of the main types of gas storage, and its number is second only to the depleted gas reservoir type gas storage. The large-scale application of the present invention can greatly improve the efficiency of storage construction, and has broad application prospects.

[0091] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any person familiar with the technology within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

[0092] In the description of the present invention, unless otherwise specified, "plurality" means two or more than two; the orientations or positional relationships indicated by the terms "upper", "lower", "left", "right", "inner", "outer", "front end", "rear end", "head", "tail", etc. are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", "third", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0093] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connection" 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 a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0094] 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 be extended to equivalent substitutions of these features understood by ordinary technicians in the relevant field. It should also be understood that the terms used herein are only used for the purpose of describing specific embodiments and are not meant to be limiting.

[0095] The "one embodiment" or "embodiment" mentioned in the specification means that the specific features, structures or characteristics described in conjunction with the embodiment are included in at least one embodiment of the present invention. Therefore, the phrases "one embodiment" or "embodiment" appearing in various places throughout the specification do not necessarily refer to the same embodiment.

[0096] Although the embodiments disclosed in the present invention are as above, the contents described are only embodiments adopted for facilitating the understanding of the present invention and are not intended to limit the present invention. Any technician in the technical field to which the present invention belongs can make any modifications and changes in the form and details of the implementation without departing from the spirit and scope disclosed in the present invention, but the patent protection scope of the present invention shall still be subject to the scope defined in the attached claims.

Claims

1. A water-soluble cavity making system for salt cavern gas storage, characterized in that: include: A first treatment device disposed on the ground, which is used to preliminarily treat the cavitation water, wherein the first treatment device is a first device selected from a heating device, a magnetizing device and a dosing device; A wellhead conveying device is connected to the first treatment device and is used to dissolve the salt cavity using the treated cavity-making water in a forward circulation or reverse circulation manner.

2. The water-soluble cavity-making system according to claim 1, characterized in that: The water-soluble cavity-making system further includes: a second processing device, which is a second device selected from a heating device, a magnetizing device and a dosing device.

3. The water-soluble cavity-making system according to claim 2, characterized in that: The two processing devices are respectively a heating device and a magnetizing device, wherein the magnetizing device is arranged between the heating device and the wellhead conveying device.

4. The water-soluble cavity-making system according to claim 2, characterized in that: The two treatment devices are a heating device and a dosing device, wherein the heating device and the dosing device are respectively connected to the wellhead conveying device, and the dosing device is used to add salt solvent to the cavitation water heated by the heating device and transported to the wellhead conveying device.

5. The water-soluble cavity-making system according to claim 2, characterized in that: The two treatment devices are a magnetizing device and a dosing device, wherein the magnetizing device and the dosing device are respectively connected to the wellhead conveying device, and the dosing device is used to add salt solvent to the cavity making water magnetized by the magnetizing device and conveyed to the wellhead conveying device.

6. The water-soluble cavity-making system according to any one of claims 3 to 5, characterized in that: The water-soluble cavity making system also includes: a third processing device, which is a third device selected from a heating device, a magnetizing device and a dosing device, wherein the magnetizing device is arranged between the heating device and the wellhead conveying device, and the dosing device is connected to the wellhead conveying device.

7. The water-soluble cavity-making system according to any one of claims 1 to 6, characterized in that: The water-soluble cavity making system also includes: at least one swirl short section connected to the bottom of the cavity making inner pipe column, the setting depth of the at least one swirl short section corresponds to the bottom of the cavity making outer pipe column and is close to the top of the salt cavity, wherein the swirl short section is configured to form a swirl when the cavity making water flows through the swirl short section in a reverse circulation cavity making manner.

8. The water-soluble cavity-making system according to claim 7, characterized in that: The swirl sub includes: A central tube having a central through hole formed therein, wherein the inner diameter of the central through hole is the same as the inner diameter of the lumen-making inner tube column; and The steel belt is fixed on the central tube in a spiral winding manner, so that the cavity-making water rotates along the steel belt around the central tube to generate a vortex.

9. The water-soluble cavity-making system according to any one of claims 1 to 8, characterized in that: The dosing device comprises: First skid-mounted platform; A liquid storage tank and an injection pump installed on the first skid-mounted platform, wherein the liquid storage tank is used to hold medicine, and the injection pump is connected to the liquid storage tank and is used to control the injection amount and / or injection speed of the medicine; A liquid level monitor disposed in the liquid storage tank; and A first gate is disposed at the outlet end of the injection pump.

10. The water-soluble cavity-making system according to any one of claims 1 to 9, characterized in that: The magnetizing device comprises: Second skid-mounted platform; a plurality of magnetizing devices mounted on the second skid-mounted platform; A conveying pipe extending through each magnetizing device, wherein an electromagnetic coil wound on the conveying pipe is disposed inside each of the magnetizing devices; A second gate, the magnetizing device is connected to the wellhead conveying device via the second gate.

11. The water-soluble cavity-making system according to any one of claims 1 to 10, characterized in that: The wellhead conveying device is configured to adopt a positive circulation method in the initial bottom pit construction stage and a reverse circulation method for cavity dissolution in the cavity construction stage; The heating device heats the cavity creation water to at least 50° C. The cavity-making water is fresh water or low-concentration brine.

12. A water-soluble cavity-making method for salt cavern gas storage, characterized in that: include: Performing preliminary treatment on the cavitation water by a first treatment device arranged on the ground, wherein the preliminary treatment is selected from one of heating, electromagnetic treatment and adding a reagent; The treated cavitation water is used to dissolve the salt cavity in a positive circulation or reverse circulation cavitation method.

13. The water-soluble cavity-making method according to claim 12, characterized in that: The water-soluble cavity-forming method is implemented by the water-soluble cavity-forming system according to any one of claims 1 to 11.

Images