A device and method for layering and emptying brine in a salt cavern cavity residue layer

Abstract

The application discloses a salt cave solution cavity residue layer brine layering emptying device and method, and belongs to the technical field of salt cave gas storage, which comprises a U-shaped double-layer pipe column, the U-shaped double-layer pipe column comprises a Y-shaped pipe group and an L-shaped pipe, the lowest end pipe opening of the Y-shaped pipe group is connected with the transverse pipe opening of the L-shaped pipe, the Y-shaped pipe group comprises a plurality of Y-shaped double-layer pipes, the Y-shaped double-layer pipe comprises a vertical pipe part and inclined pipe parts connected on both sides of the vertical pipe part, and the plurality of Y-shaped double-layer pipes are sequentially connected through the vertical pipe parts, and the brine is emptied through layering by the device. The application significantly improves the salt cave solution cavity structural stability and the utilization rate of the gas storage space, provides important technical support for the development and application of the salt cave compressed air energy storage technology, and helps to promote the commercialization and large-scale development of the technology.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of salt cavern gas storage, in particular to a salt cavern solution cavity residual layer brine stratified emptying device and method. BACKGROUND

[0002] The salt cavern gas storage is a large-scale closed space constructed in the underground salt rock layer through water-soluble mining technology, and the dissolved salt rock forms a container with excellent geological sealing performance. The facility can be used for large-scale storage during the low consumption period of natural gas, and can be used for gas supply through efficient recovery mechanism during the peak consumption period, so as to effectively balance the peak and valley difference of the regional gas supply system.

[0003] The salt rock stratum in China belongs to typical lacustrine sedimentary layered salt rock, and the salt layer interlayer accounts for a high proportion. The salt body is heterogeneous, which leads to slow cavity construction speed and low stability of the cavity body which is easily affected by the collapse of the interlayer. At the same time, the salt rock in China generally contains insoluble substances, mainly composed of gypsum and mudstone. During the solution cavity process, the thin interlayer passing through the cavity will be dissolved, and these insoluble substances will settle at the bottom of the cavity. A large number of experiments show that the void ratio of the insoluble residue at the bottom of the cavity can be as high as 50%, and the voids between these insoluble substances are well connected, with large permeability. This makes part of the high-concentration brine exist in the pores and voids of the insoluble substances, which cannot be discharged through the brine discharge pipe at the wellhead. As the proportion of insoluble space increases, the available cavity inside the salt cavern gradually decreases, thereby reducing the internal air storage capacity.

[0004] In order to solve this problem, the prior art connects a new well to the lowest point of the salt cavern bottom to pump out the brine in the space between the sediments and the pores of the sediments, thereby forming a gas storage space and increasing the cavity capacity to store more gas. However, the current brine discharge method has a problem, that is, directly discharging brine from the bottom of the sediment layer. Because the bottom of the sediment layer has been subjected to long-term pressure from the upper layer, the porosity is low and the flowability of the brine is poor, which causes the high-concentration brine to be retained, so that the brine concentration at the bottom is higher than that in the upper part, thereby causing the pressure at the bottom to be higher than that in the upper part. If the brine is directly discharged from the bottom, the cavity pressure will drop suddenly, the original pressure balance of the solution cavity will be destroyed, and the solution cavity collapse and sediment compaction may be caused. This not only reduces the effective capacity of the solution cavity, but also causes the permeability and porosity of the pores to decrease due to the compaction of the bottom sediments, making it more difficult to discharge the brine, further affecting the effective capacity of the solution cavity. This results in the difficulty of the prior art in effectively discharging the brine at the bottom of the sediments, thereby limiting the further application of the cavity expansion method by discharging the brine at the bottom of the sediments.

[0005] Based on the above problems, a salt cavern solution cavity residual layer brine stratified emptying device and method are provided. SUMMARY

[0006] The application aims to provide a salt cave solution cavity residual layer brine layered emptying device and method to solve the problems in the background art.

[0007] To achieve the above-mentioned purpose, the application provides a salt cave solution cavity residual layer brine layered emptying device, comprising a U-shaped double-layer pipe column, the U-shaped double-layer pipe column comprising a Y-shaped pipe group and an L-shaped pipe, the lowest end pipe opening of the Y-shaped pipe group being connected with the transverse pipe opening of the L-shaped pipe, the Y-shaped pipe group comprising a plurality of Y-shaped double-layer pipes, the Y-shaped double-layer pipe comprising a vertical pipe part and inclined pipe parts connected on both sides of the vertical pipe part, the plurality of Y-shaped double-layer pipes being connected in sequence through the vertical pipe parts.

[0008] Preferably, first control valves are arranged at the two end pipe openings of the Y-shaped double-layer pipe;

[0009] The Y-shaped double-layer pipe comprises an inner pipe and an outer pipe, a vibration screen is symmetrically arranged inside the outer pipe below the first control valve, and the vibration screen is attached to the outer wall of the inner pipe.

[0010] Preferably, an electric submersible pump is arranged in the suction cavity inside the outer pipe, and the pump head of the electric submersible pump extends into the inner pipe.

[0011] Preferably, a flow meter is arranged on the inner wall of the middle upper part of the inner pipe, and a pressure sensor and a concentration sensor are arranged on the inner wall of the middle lower part of the inner pipe.

[0012] Preferably, a first automatic dosing device is arranged at the branch opening of the outer pipe, and the first automatic dosing device extends into the inner pipe.

[0013] Preferably, the L-shaped pipe is composed of a vertical first double-layer pipe column and a transverse second double-layer pipe column, and the first double-layer pipe column and the second double-layer pipe column are connected through a turning connecting pipe.

[0014] Preferably, a second control valve is arranged inside the second double-layer pipe column, a total control valve is arranged at the top end pipe opening of the first double-layer pipe column, and a second automatic dosing device is arranged at the middle position of the outer layer pipe of the first double-layer pipe column.

[0015] The application further provides a salt cave solution cavity residual layer brine layered emptying method, which is realized through the above-mentioned layered emptying device and specifically comprises the following steps:

[0016] S1, the height of the salt cave solution cavity residual layer is calculated through ultrasonic technology and is transmitted into a computer database;

[0017] S2, the height obtained in S1 divides the residue layer into three layers, and a Y-shaped double-layer pipe is designed according to the height of each layer, and the Y-shaped double-layer pipe is connected with the L-shaped pipe through a flange to form a layered emptying device, and the top end of the Y-shaped double-layer pipe in the uppermost layer is sealed;

[0018] S3, a new wellbore is drilled by using directional drilling technology, so that the new wellbore can accurately reach the lowest point of the residue layer, and wellbore reinforcement measures are taken to prevent the wellbore from collapsing, and then the layered emptying device formed in S2 is lowered into the new wellbore, so that the top end of the Y-shaped double-layer pipe in the uppermost layer contacts the top of the residue layer;

[0019] S4, the halogen is sequentially discharged in the order of top-middle-bottom, the control valve at the corresponding position is controlled to be opened, the power for discharging the halogen is provided by the electric submersible pump device, the residue in the halogen discharge port is removed by the vibrating screen, and the scale remover is regularly added by the automatic dosing device, and the halogen discharge work is completed.

[0020] Preferably, in S4, the parameter data is obtained in real time through a pressure sensor, a flow meter and a concentration sensor, the parameter data is transmitted into a computer database, the XGBoost model is established by machine learning in combination with the on-site data of the salt mine to predict and set the pressure, flow and concentration thresholds of the closed control valve.

[0021] Preferably, in S4, according to the set threshold value, when the pressure, flow and concentration data of the current halogen discharge layer decrease to the set threshold value, it indicates that the halogen in the layer has been basically discharged, and then the corresponding control valve is automatically closed, the next layer control valve is opened, the residue layer halogen is sequentially discharged in layers, and after all the halogen is discharged, the total control valve is closed.

[0022] Therefore, the salt cave solution cavity residue layer halogen layered emptying device and method has the following beneficial effects:

[0023] (1) Optimize the discharge of the halogen in the sediment void: the layered emptying device is used to discharge the halogen in the sediment in stages, the sediment void occupied by the halogen is released, and the halogen and the sediment particles are separated through the vibrating screen structure.

[0024] (2) Improve the stability of the solution cavity structure: through the layered emptying design, the upper layer of low-concentration halogen is discharged first, and then the bottom layer of high-concentration halogen is processed, so that the sudden change of the solution cavity pressure caused by one-time pumping is avoided, and the risk of collapse of the top of the salt cavity is reduced.

[0025] (3) Improve the utilization rate of the gas storage space: the design can release the sediment void space originally occupied by the halogen and convert it into a usable gas storage space, effectively increasing the capacity of the salt cave gas storage, solving the problem of large-scale gas storage in low-grade and multi-interlayer salt caves, and improving the utilization value of the salt cave.

[0026] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of an embodiment of the present invention;

[0028] Figure 2 This is a schematic diagram of the internal structure of the Y-shaped double-layer tube according to an embodiment of the present invention;

[0029] Figure 3 This is a schematic diagram of the steps of the venting method according to an embodiment of the present invention;

[0030] Figure 4 This is a schematic diagram of the venting method according to an embodiment of the present invention;

[0031] Figure label:

[0032] 1. L-shaped tube; 11. First double-layer tube column; 12. Second double-layer tube column; 13. Second control valve; 14. Main control valve; 2. Y-shaped double-layer tube; 3. First control valve; 4. Vibrating screen; 5. Electric submersible pump; 6. Flow meter; 7. Pressure sensor; 8. Concentration sensor; 9. First automatic dosing device; 10. Insoluble residue; 101. Brine. Detailed Implementation

[0033] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0034] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.

[0035] Example

[0036] like Figures 1-2 As shown, the present invention provides a stratified brine drainage device for the residual layer of a salt cavern, comprising a U-shaped double-layer tube column, the U-shaped double-layer tube column comprising a Y-shaped tube group and an L-shaped tube 1, the lowest end of the Y-shaped tube group being connected to the transverse end of the L-shaped tube 1, the Y-shaped tube group comprising multiple Y-shaped double-layer tubes 2, each Y-shaped double-layer tube 2 comprising a vertical tube portion and an oblique tube portion connected to both sides of the vertical tube portion, the multiple Y-shaped double-layer tubes 2 being sequentially connected through the vertical tube portion to form a multi-layer brine drainage channel.

[0037] The L-shaped pipe 1 is composed of a vertical first double-layer pipe column 11 and a horizontal second double-layer pipe column 12, which are connected by a turning connecting pipe (such as a 90° elbow double-layer pipe), and the connection is sealed by welding or flange. The second double-layer pipe column 12 is internally provided with a second control valve 13 for controlling the on-off of the horizontal pipe; the top end of the first double-layer pipe column 11 is provided with a total control valve 14 for controlling the total on-off of the whole device. The second automatic dosing device is arranged at the middle position of the outer pipe of the first double-layer pipe column 11 for supplementing the scale remover into the vertical pipe.

[0038] In this embodiment, all the pipe columns are made of corrosion-resistant alloy steel pipes with sufficient strength to withstand the pressure and temperature changes of the brine; the turning connecting pipe is welded to ensure the firmness and sealing of the connection; in this embodiment, the flanges are used to connect the pipes, and the flanges are preferably made of corrosion-resistant alloy steel materials with high strength, excellent toughness and anti-deformation performance, which can withstand the high-pressure environment in the salt cave solution cavity to ensure the stability and sealing of the connection.

[0039] The first control valve 3 is arranged at the pipe opening of the two ends of the Y-shaped double-layer pipe 2, and in this embodiment, the valve body is made of corrosion-resistant stainless steel, and a corrosion-resistant and high-temperature-resistant sealing material (such as fluororubber) is selected to ensure the sealing of the valve. An electric gate valve can be selected to control the on-off of each layer of brine.

[0040] The Y-shaped double-layer pipe 2 includes an inner pipe and an outer pipe, and the outer pipe is symmetrically provided with a vibrating screen 4 below the first control valve 3. The vibrating screen 4 is made of high-hardness and corrosion-resistant stainless steel material, which can resist the chemical corrosion of the brine, maintain the integrity and screening performance of the screen, and install a corrosion-resistant vibrating motor to ensure the long-term stable operation of the screen under high-frequency vibration. The screen aperture is ≤1mm.

[0041] The vibrating screen 4 is attached to the outer wall of the inner pipe. In this embodiment, the vibrating screen 4 can be connected to the inner wall of the outer pipe through a spring support and tightly attached to the outer wall of the inner pipe. The vibrating screen 4 can be driven by the vibrating motor during brine discharge to achieve efficient filtration of residual particles.

[0042] The electric submersible pump 5 is arranged in the suction cavity inside the outer pipe. The electric submersible pump 5 is made of corrosion-resistant stainless steel and other materials, which can resist the chemical corrosion of the brine. The motor is designed to withstand high temperature and high pressure, and can stably operate in the harsh environment of the salt cave solution cavity. The pump head of the electric submersible pump 5 extends into the inner pipe to provide power for brine pumping, and the power is selected according to the depth of the salt cave and the viscosity of the brine.

[0043] A flow meter 6 is arranged on the inner wall of the middle upper part of the inner tube, which is made of corrosion-resistant stainless steel and the like, has high measurement accuracy, and can accurately measure the flow of brine in the middle upper part of the inner tube. A pressure sensor 7 and a concentration sensor 8 are arranged on the inner wall of the middle lower part of the inner tube, which are made of corrosion-resistant metal materials, can accurately measure the pressure and concentration of the brine, and take protective measures (such as installing a protective sleeve).

[0044] A first automatic dosing device 9, such as a plunger type metering pump, is arranged at the branch opening of the outer tube, and the outlet pipe thereof extends into the inner part of the inner tube. The dosing frequency is set according to the actual situation, such as 50-100 mL per hour per row of brine.

[0045] As shown in Figures 3-4 , the layered emptying device is used to perform layered emptying of brine, which specifically includes the following steps:

[0046] S1, the height of the residue layer in the salt cavern solution cavity is calculated by ultrasonic technology and transmitted to the computer database. For example, a pulse ultrasonic sensor with a frequency of 50 kHz is used to emit ultrasonic signals to the bottom of the solution cavity, and the height of the residue layer is calculated according to the echo time. The measurement accuracy is controlled within ±5 cm, and the data is transmitted to the ground computer database in real time.

[0047] S2, according to the total height (set as H) of the residue layer obtained in S1, the residue layer is evenly divided into three layers, each layer has a height of H / 3. Y-shaped double-layer pipes 2 are customized for each layer height, the vertical pipe part has a length of H / 3, 2H / 3 and H (from bottom to top) respectively, and the inclined pipe part has an angle of 45°. This ensures that the brine discharge openings of each layer are evenly distributed in the residue layer. The Y-shaped double-layer pipes 2 and the L-shaped pipes 1 are connected by flanges according to the design requirements to form a layered emptying device. The top end pipe opening of the uppermost Y-shaped double-layer pipe 2 is sealed by a blind flange to prevent impurities from entering the upper layer.

[0048] S3, a directional drilling equipment (such as a rotary steerable system with a screw drill) is used to drill a new wellbore. During drilling, the borehole trajectory is monitored in real time by a while-drilling inclinometer (with an accuracy of ±0.1°) to ensure that the wellbore accurately reaches the lowest point of the residue layer (with an error of ±10 cm). After the wellbore drilling is completed, a casing is lowered and cement slurry is injected for well wall reinforcement. After the cement slurry is solidified for 48 hours, the layered emptying device is lowered into the wellbore, so that the top end pipe opening of the uppermost Y-shaped double-layer pipe 2 contacts the top of the residue layer. This process can be confirmed by pressure sensor 7 feedback data or other means, such as Figure 1As shown, the periphery of the layered emptying device is insoluble residue 10, and the upper end is brine 101.

[0049] S4, the brine discharge sequence is from top to bottom (i.e. first discharge the uppermost layer, then the middle layer, and finally the lower layer). Open the total control valve 14, the second control valve 13 and the first control valve 3 of the uppermost Y-shaped double-layer pipe 2, start the electric submersible pump 5 (frequency 50 Hz), and the brine is discharged through the inner pipe via the L-shaped pipe 1. During the brine discharge process, the vibrating screen 4 vibrates synchronously (frequency 20 Hz) to filter the residual particles; the first automatic dosing device 9 adds the scale inhibitor once an hour to prevent the inner pipe from scaling. The pressure sensor 7, the flow meter 6 and the concentration sensor 8 collect data in real time (sampling frequency 1 time / s), which are transmitted to the computer database, combined with the historical data of the salt mine site (such as the salt cavern temperature, brine density, etc.), and the prediction model is established by calling the XGBoost library through the Python programming language to dynamically set the threshold values of the closing of the control valves of each layer, such as the pressure threshold value 0.8 MPa, the flow threshold value 5 m 3 / h, and the concentration threshold value 300 g / L. When the three parameters of the current brine discharge layer decrease below the set threshold values, the ground control system automatically closes the first control valve 3 and the electric submersible pump 5 of the layer, opens the first control valve 3 and the electric submersible pump 5 of the middle Y-shaped double-layer pipe 2, and repeats the above brine discharge process. After the lower layer brine discharge is completed, the total control valve 14 is closed, and the entire brine discharge operation is stopped.

[0050] Therefore, the salt cavern solution cavity residue layer brine layered emptying device and method of the present application solve the problems in the background art, significantly improve the stability of the salt cavern solution cavity structure and the utilization rate of the gas storage space, provide important technical support for the development and application of the salt cavern compressed air energy storage technology, and help to promote the commercialization and large-scale development of the technology.

[0051] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application and not to limit them, although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can still be modified or replaced by equivalents, and these modifications or equivalent replacements cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present application.

Claims

1. A salt cavern residual layer brine layering emptying device characterized in that: it comprises a U-shaped double-layer pipe column, the U-shaped double-layer pipe column comprises a Y-shaped pipe group and an L-shaped pipe, the lowest end of the Y-shaped pipe group is connected with the transverse pipe of the L-shaped pipe, the Y-shaped pipe group comprises a plurality of Y-shaped double-layer pipes, the Y-shaped double-layer pipe comprises a vertical pipe part and inclined pipe parts connected on both sides of the vertical pipe part, and the plurality of Y-shaped double-layer pipes are sequentially connected through the vertical pipe parts.

2. The device for layering and emptying brine from the residue layer of a salt cavern solution cavity according to claim 1, characterized in that: first control valves are arranged at the two ends of the Y-shaped double-layer pipe; the Y-shaped double-layer pipe comprises an inner pipe and an outer pipe, a vibration screen is symmetrically arranged inside the outer pipe below the first control valve, and the vibration screen is attached to the outer wall of the inner pipe.

3. The device for layering and emptying brine from the residue layer of a solution cavity of a salt cavern according to claim 2, characterized in that: an electric submersible pump is arranged in the suction cavity inside the outer pipe, and the pump head of the electric submersible pump extends into the inner pipe.

4. The device according to claim 2, characterized in that: a flowmeter is arranged on the inner wall of the middle upper part of the inner pipe, and a pressure sensor and a concentration sensor are arranged on the inner wall of the middle lower part of the inner pipe.

5. The device according to claim 2, characterized in that: a first automatic dosing device is arranged at the branch opening of the outer pipe, and the first automatic dosing device extends into the inner pipe.

6. The device for brine layering and emptying of the residue layer of a salt cavern solution cavity according to claim 2, characterized in that: the L-shaped pipe is composed of a vertical first double-layer pipe column and a transverse second double-layer pipe column, and the first double-layer pipe column and the second double-layer pipe column are connected through a turning connecting pipe.

7. The device according to claim 6, characterized in that it comprises: a second control valve is arranged in the second double-layer pipe column, a total control valve is arranged at the top end of the first double-layer pipe column, and a second automatic dosing device is arranged at the middle position of the outer pipe of the first double-layer pipe column.

8. A method for layered discharge of brine from a salt cavern residue layer, characterized in that, The layering emptying device of any one of claims 1-7 is realized, and specifically comprises the following steps: S1: The height of the residual layer of the salt cavern solution cavity is calculated by ultrasonic technology and is transmitted to the computer database; S2: The residual layer is evenly divided into three layers according to the height obtained in S1, a Y-shaped double-layer pipe is designed according to the height of each layer, the Y-shaped double-layer pipe is connected with the L-shaped pipe through a flange to form a layering emptying device, and the top end of the Y-shaped double-layer pipe of the uppermost layer is sealed; S3: A new wellbore is drilled by directional drilling technology, so that the new wellbore can accurately reach the lowest point of the residual layer, and well wall reinforcement measures are taken to prevent the wellbore from collapsing, and then the layering emptying device formed in S2 is lowered into the new wellbore, so that the top end of the Y-shaped double-layer pipe of the uppermost layer contacts the top of the residual layer; S4: The brine is discharged in the order of top-middle-bottom, the control valve at the corresponding position is controlled to be opened, the electric submersible pump device provides the power for discharging the brine, the residual layer is removed by the vibration screen, and the automatic dosing device is regularly used to discharge the scale remover to complete the brine discharge work.

9. The method according to claim 8, characterized in that: In S4, the parameter data is obtained in real time through the pressure sensor, the flowmeter and the concentration sensor, the parameter data is transmitted to the computer database, the XGBoost model is established through machine learning combined with the on-site data of the salt mine to predict and set the pressure, flow and concentration threshold values of the closed control valve.

10. The method according to claim 9, characterized in that; In the S4, according to the set threshold, when the pressure, flow, concentration data of the current brine layer decrease to the set threshold, it indicates that the brine in the layer has been basically exhausted, then the corresponding control valve is automatically closed, and the next layer control valve is opened, so that the brine in the residue layer is sequentially exhausted in layers, and after the total exhaustion, the total control valve is closed.

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