Method and system for testing the connectivity of the sediment at the bottom of the cavity of an old storage of halite mining

Abstract

The application provides a method and system for testing the connectivity of sediment at the bottom of a cavity of a salt mine brine extraction old storage. The system comprises a storage, wherein the cavity bottom has sediment; an injection well, which is in communication with the top of the storage, and the wellhead of the injection well is connected with an injection flow rate and pressure measuring mechanism; a test well, which is in communication with the storage at a position within the sediment area at the bottom of the storage, and the wellhead of the test well is connected with a discharge flow rate and pressure measuring mechanism; the method comprises: the test liquid injected by the injection well flows through the sediment at the bottom of the cavity of the storage, and then flows into the test well and is discharged through the test well; the injection flow rate and pressure measuring mechanism measures the flow rate and pressure at the injection end, and the discharge flow rate and pressure measuring mechanism measures the flow rate and pressure at the discharge end, thereby solving the technical problem that the characteristics of the sediment at the bottom of the cavity of the storage are difficult to test.

Description

Technical Field

[0001] This invention relates to the technical field of construction technology for gas storage and energy storage facilities, and in particular to a method and system for testing the connectivity of sediment at the bottom of an old brine storage tank in a salt mine. Background Technology

[0002] Salt cavern gas storage involves drilling to reach the target layer, then mechanically pumping fresh water from the surface into the salt layer through tubing. Taking advantage of the water-soluble nature of salt minerals, the water dissolves into the salt layer, creating a cavity of a specific shape and volume for storing gases such as natural gas. Similar methods can also be used to construct energy storage facilities for storing pressurized gases.

[0003] The bottom of gas and energy storage facilities typically contains sediment, which is a blocky or granular insoluble material produced during the dissolution process. This sediment accumulates to form loose deposits. Due to geological conditions, some gas or energy storage facilities are located in areas with poor-quality salt rock formations and high insoluble content.

[0004] Based on the sediment formation process, the main sources of sediment are as follows: (1) During the cavity construction process, as a large amount of sodium chloride in the salt rock layer is dissolved, most of the insoluble substances in the salt layer are released, forming insoluble matter of varying particle sizes. By measuring the particle size of the brine extracted on site, only a very small portion of the fine particles (particle size <1mm) of insoluble matter return to the ground with the brine through the brine discharge pipe column. The remaining majority of insoluble matter particles settle under their own gravity and gradually accumulate at the bottom of the cavity of the gas storage or energy storage tank, forming sediment. (2) Salt mines in layered salt rock strata are characterized by numerous interlayers (such as anhydrite, mudstone, and glaucophane layers), and the mutual development of soluble salt layers and interlayers. These interlayers are difficult to dissolve. Therefore, during cavity creation, the soluble salt layers dissolve, exposing the insoluble and non-soluble interlayers in the cavity-creating section. As the salt layer above the non-soluble interlayer dissolves, the interlayer is suspended and immersed in unsaturated brine for a long time. The soluble components in the interlayer dissolve rapidly, forming a large number of fissures inside the interlayer. At the same time, the mudstone interlayer contains a relatively large amount of clay minerals. The clay minerals swell when they come into contact with water, causing more microfissures to be generated in the interlayer. Brine enters the interior of the interlayer along these fissures, and more soluble substances and mudstone cement soften and dissolve, further increasing the size of the fissures in the interlayer. During the water-soluble cavity creation process, a large amount of insoluble matter produced by the dissolution of salt rock accumulates at the bottom of the cavity.

[0005] The formation and accumulation of insoluble substances constrain the construction of salt cavern gas and energy storage facilities in many ways. This affects not only the progress of cavern construction but also the gas storage efficiency of the gas storage facility and the energy storage efficiency of the energy storage facility. In areas with low-grade salt rock in the geological strata for salt cavern gas / energy storage construction, there are more insoluble substances, resulting in a low cavern formation rate and high cost per cubic meter of storage space.

[0006] Meanwhile, the insoluble matter accumulated at the bottom of the cavity often takes the form of granules or lumps. The cavity is located at a great depth underground and has a large space. Sampling the sediment at the bottom of the cavity is technically difficult, making it hard to test the insoluble sediment at the bottom of the cavity. Summary of the Invention

[0007] The purpose of this invention is to provide a method and system for testing the connectivity of sediment at the bottom of old brine storage tanks in salt mines, so as to solve the technical problem that it is difficult to test the characteristics of sediment at the bottom of storage tanks.

[0008] The above-mentioned objectives of the present invention can be achieved by the following technical solutions:

[0009] This invention provides a method for testing the connectivity of sediment at the bottom of an old brine storage tank in a salt mine, using a system for testing the connectivity of sediment at the bottom of an old brine storage tank in a salt mine.

[0010] The system for testing the connectivity of sediment at the bottom of the old brine storage tank in the salt mine includes:

[0011] A storage tank, the bottom of which contains sediment;

[0012] An injection well is connected to the top of the storage tank, and the wellhead of the injection well is connected to an injection flow and pressure measuring mechanism.

[0013] The test well is connected to the storage tank at a location located in the sediment area at the bottom of the storage tank, and the wellhead of the test well is connected to a discharge flow and pressure measuring mechanism.

[0014] The method for testing the connectivity of the bottom sediment in the old brine storage tank of a salt mine includes:

[0015] The test fluid injected into the storage tank by the injection well flows through the sediment at the bottom of the storage tank, then flows into the test well and is discharged through the test well.

[0016] The injection flow and pressure measuring mechanism measures the flow and pressure at the injection end, and the discharge flow and pressure measuring mechanism measures the flow and pressure at the discharge end.

[0017] In a preferred embodiment, the method for testing the connectivity of sediment at the bottom of the old brine storage tank in the salt mine includes a flowability test. The flowability test includes: continuously injecting test liquid into the storage tank at a first flow rate through the injection well; and after the flow rate and pressure at the discharge end stabilize, measuring and recording the flow rate and pressure at the discharge end, as well as the pressure at the injection end.

[0018] In a preferred embodiment, the flowability test includes: after completing the test of the first flow rate, gradually increasing the flow rate value based on the first flow rate, and measuring and recording the flow rate and pressure at the discharge end and the pressure at the injection end after stabilization.

[0019] In a preferred embodiment, the method for testing the connectivity of sediment at the bottom of the old brine storage tank in a salt mine includes a maximum discharge flow rate test. The maximum discharge flow rate test includes: closing the test well, injecting test liquid into the storage tank through the injection well until the pressure at the injection end is a first pressure; stopping the injection of test liquid into the injection well and closing the injection well, opening the test well, and measuring and recording the flow rate and pressure at the discharge end.

[0020] In a preferred embodiment, the maximum discharge flow rate test includes: after completing the first pressure test, the injection well continues to inject test fluid into the storage tank, and the pressure value is gradually increased to the upper limit pressure of the storage tank cavity based on the first pressure by using a segmented pressurization method, and the flow rate and pressure at the discharge end are measured and recorded after the injection well is closed and the test well is opened.

[0021] In a preferred embodiment, the maximum discharge flow rate test is performed after the flowability test.

[0022] In a preferred embodiment, the frictional resistance of the test well tubing, the frictional resistance of the injection well tubing, and the sediment frictional resistance are calculated based on the flow rate and pressure at the injection end and the flow rate and pressure at the discharge end.

[0023] In a preferred embodiment, the salt mine brine old storage chamber bottom sediment connectivity test system includes a first liquid storage tank, a water injection pump truck and a first valve connected in series, and the first valve is connected to the injection well through the injection main pipeline.

[0024] In a preferred embodiment, the salt mine brine old storage chamber bottom sediment connectivity test system includes a second storage tank and a second valve connected in series, with the second valve connected to the test well via a discharge main line.

[0025] In a preferred embodiment, the first storage tank is connected to the second storage tank, and the test liquid in the second storage tank can flow into the first storage tank to achieve circulation.

[0026] This invention provides a system for testing the connectivity of sediment at the bottom of an old brine storage tank in a salt mine, applicable to the aforementioned method for testing the connectivity of sediment at the bottom of an old brine storage tank in a salt mine. The system comprises:

[0027] A storage tank, the bottom of which contains sediment;

[0028] An injection well is connected to the top of the storage tank, and the wellhead of the injection well is connected to an injection flow and pressure measuring mechanism.

[0029] A test well, which is connected to the side or bottom of the storage tank, and the wellhead of the test well is connected to a discharge flow and pressure measuring mechanism;

[0030] The test fluid injected into the storage tank through the injection well can flow through the sediment at the bottom of the storage tank, then flow into the test well and be discharged through the test well; the injection flow and pressure measuring mechanism is used to measure the flow and pressure at the injection end, and the discharge flow and pressure measuring mechanism is used to measure the flow and pressure at the discharge end.

[0031] The features and advantages of this invention are:

[0032] The connection between the test well and the storage tank is located on the side or bottom of the storage tank, allowing the test fluid to flow through the sediment at the bottom of the storage tank into the test well and then out. By injecting test fluid into the injection well and returning test fluid from the test well, the connectivity between the injection well, the test well, the storage tank, and the sediment, as well as the physical properties of the sediment, are tested. This verifies the pore space and flow resistance of the sediment at the bottom, providing effective data support for subsequent gas injection and brine discharge, as well as the calculation of the storage tank's cavity volume. It also facilitates the utilization of the sediment formed by insoluble matter at the bottom of the storage tank cavity, significantly increasing the usable storage capacity of the salt mine storage tank. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 A schematic diagram of the structure of the salt mine brine old storage tank bottom sediment connectivity test system provided by the present invention;

[0035] Figure 2 This is a schematic diagram of the fluidity test in the method for testing the connectivity of sediment at the bottom of an old brine storage tank provided by the present invention.

[0036] Figure 3 This is a schematic diagram of the maximum discharge flow rate test in the method for testing the connectivity of sediment at the bottom of an old brine storage tank in a salt mine, provided by the present invention.

[0037] Figure 4 The table showing the relationship between the empirical formula for the resistance coefficient, Reynolds number, and flow pattern in the test method for the connectivity of sediment at the bottom of old brine storage tanks in salt mines provided by this invention.

[0038] Explanation of icon numbers:

[0039] 10. Injection well; 11. Injection flow and pressure measurement mechanism;

[0040] 21. First storage tank; 22. First valve; 23. Injection main line; 24. Water injection pump truck;

[0041] 30. Test well; 31. Discharge flow and pressure measurement mechanism;

[0042] 41. Second storage tank; 42. Second valve; 43. Main discharge line;

[0043] 50. Storage tank; 51. Sediment. Detailed Implementation

[0044] 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 only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0045] The properties of insoluble sediment vary from region to region, including porosity and permeability. Due to a lack of understanding of the properties of sediment at the bottom of salt mine storage tanks, it is unclear whether the voids in the sediment can be utilized during storage, thus reducing the usable storage capacity of the tanks.

[0046] Option 1

[0047] This invention provides a method for testing the connectivity of sediment at the bottom of old brine storage tanks in salt mines, employing a system for testing the connectivity of sediment at the bottom of old brine storage tanks in salt mines; such as Figure 1 As shown, the salt mine brine storage tank bottom sediment connectivity test system includes: storage tank 50, injection well 10 and test well 30. Sediment 51 exists at the bottom of storage tank 50; injection well 10 is connected to the top of storage tank 50, and injection flow and pressure measuring mechanism 11 is connected to the wellhead of injection well 10; the connection position between test well 30 and storage tank 50 is located in the sediment area at the bottom of storage tank 50, and discharge flow and pressure measuring mechanism 31 is connected to the wellhead of test well 30.

[0048] The method for testing the connectivity of the sediment at the bottom of the old brine storage chamber in this salt mine includes:

[0049] The test fluid injected into the storage tank 50 by the injection well 10 flows through the sediment 51 at the bottom of the storage tank 50, then flows into the test well 30 and is discharged through the test well 30.

[0050] The injection flow and pressure measuring mechanism 11 measures the flow and pressure at the injection end, and the discharge flow and pressure measuring mechanism 31 measures the flow and pressure at the discharge end.

[0051] In this testing method, the connection between the test well 30 and the storage tank 50 is set at the side or bottom of the storage tank 50, so that the test liquid can flow through the sediment 51 at the bottom of the storage tank 50 and then into the test well 30 and out. The test liquid is injected into the injection well 10 and returned from the test well 30 to test the connectivity between the injection well 10, the test well 30, the storage tank 50 and the sediment 51, as well as the physical properties of the sediment 51. This verifies the pore space and flow resistance of the bottom sediment 51, providing effective data support for subsequent gas injection and brine discharge and the calculation of the cavity volume of the storage tank 50. It also facilitates the utilization of the sediment 51 formed by insoluble matter at the bottom of the storage tank 50 cavity, and significantly increases the usable storage capacity of the salt mine storage tank 50.

[0052] In one embodiment, the method for testing the connectivity of the sediment at the bottom of the old brine storage chamber in the salt mine includes a fluidity test, such as... Figure 2 As shown, the flowability test includes: continuously injecting test liquid into the storage tank 50 at a first flow rate from the injection well 10. After the flow rate and pressure at the discharge end stabilize, the flow rate and pressure at the discharge end, as well as the pressure at the injection end, are measured and recorded to test the connectivity of the injection well 10, test well 30, storage tank 50, and sediment 51, and to understand the influence of the injection well 10, test well 30, storage tank 50, and sediment 51 on the flow rate and pressure of the injected gas, so as to facilitate the utilization of the cavity of the storage tank 50.

[0053] Furthermore, the flowability test includes: after completing the first flow rate test, the flow rate value is gradually increased based on the first flow rate, and the flow rate and pressure at the discharge end and the pressure at the injection end are measured and recorded respectively after stabilization, so as to obtain the flow rate and pressure data at the discharge end when injecting test liquid at different flow rates, so as to provide effective data support for subsequent gas injection and brine discharge and the cavity volume calculation of storage tank 50.

[0054] In one specific embodiment, during the first stage of the test, the injection flow rate of injection well 10 is controlled at approximately 20 cubic meters per hour until pressure is displayed at the wellhead of test well 30. Then, the flow rate of injection well 10 is increased to 40 cubic meters per hour. After stabilizing at 40 cubic meters per hour for a period of time, the pressure and flow rate at the wellhead of test well 30 are observed. If the pressure at the wellhead of test well 30 stabilizes at a certain value, the injection flow rate of injection well 10 is further increased to 60 cubic meters per hour. After stabilizing at 60 cubic meters per hour for a period of time, the fluctuations in flow rate and pressure at the wellhead of test well 30 are observed. If the wellhead pressure and flow rate remain essentially unchanged or stabilize within a certain range, the flow rate of injection well 10 is further increased to 80 cubic meters per hour. This process is repeated until the injection rate of injection well 10 is increased to 120 cubic meters per hour. Once the flow rate at the wellhead of test well 30 stabilizes, injection in injection well 10 is stopped. During the test, the pressure and flow rate at the wellhead of injection well 10 and the pressure and flow rate at the wellhead of test well 30 are recorded at different injection flow rates and recorded in a table.

[0055] In one embodiment, the method for testing the connectivity of sediment at the bottom of the old brine storage chamber in a salt mine includes a maximum discharge flow rate test, such as... Figure 3 As shown, the maximum discharge flow rate test includes: closing test well 30, injecting test fluid into storage tank 50 through injection well 10 until the pressure at the injection end is the first pressure; stopping the injection of test fluid into injection well 10 and closing injection well 10, opening test well 30, and measuring and recording the flow rate and pressure at the discharge end. The connectivity between injection well 10, test well 30, storage tank 50, and sediment 51 is tested by the pressure difference between test well 30 and injection well 10 and the discharge flow rate at the discharge end.

[0056] Furthermore, the maximum discharge flow rate test includes: after completing the first pressure test, the injection well 10 continues to inject test fluid into the storage tank 50, and the pressure is gradually increased from the first pressure to the upper limit pressure of the storage tank 50 cavity using a segmented pressurization method. The flow rate and pressure at the discharge end are measured and recorded after the injection well 10 is closed and the test well 30 is opened. By using the segmented pressurization method, the pressure at the discharge end, the pressure difference between the two ends, and the discharge flow rate are obtained when the injection end is at different pressures.

[0057] Furthermore, conducting the maximum outflow test after the liquidity test allows the liquidity test to proceed sequentially with the maximum outflow test, thus improving the overall efficiency of the test.

[0058] In one embodiment, based on the flow rate and pressure at the injection end and the flow rate and pressure at the discharge end, the frictional resistance of the test well 30 tubing string, the frictional resistance of the injection well 10 tubing string, and the sediment frictional resistance are calculated. This allows for a quantitative understanding of the physical properties of the sediment 51 in the storage tank 50, providing effective data support for subsequent calculations of the storage tank 50's cavity volume. This facilitates the full utilization of the sediment 51 and increases the usable storage capacity of the storage tank 50. Specifically, the fluid motion state can be determined first, and different fluid states can be distinguished based on the Reynolds number. Then, based on the distinguished flow patterns such as laminar flow, hydraulically smooth flow, and hydraulically rough flow, corresponding empirical formulas are selected to calculate the resistance coefficient. Finally, corresponding empirical formulas are selected to calculate the frictional resistance h of the test well 30 tubing string and the injection well 10 tubing string. fc and h fl Then, based on the frictional resistance h of the test well 30 tubing string and the injection well 10 tubing string... fc and h fl， The frictional resistance M of sediment is calculated. This invention enables the testing of the porosity, permeability, and flow friction of sediment.

[0059] In one implementation, such as Figure 1 As shown, the salt mine brine storage chamber bottom sediment connectivity testing system includes a first storage tank 21, a water injection pump truck 24, and a first valve 22 connected in series. The first valve 22 is connected to the injection well 10 via the main injection pipeline 23. The test liquid is stored in the first storage tank 21, flows into the main injection pipeline 23 via the water injection pump truck 24, then passes through the first valve 22, flows into the wellhead of the injection well 10, and continues to flow into the wellbore of the injection well 10. The injection flow rate and pressure measurement mechanism 11 includes a pressure gauge and a flow meter installed at the wellhead to monitor the fluid pressure and flow rate flowing into the wellhead.

[0060] The first storage tank 21, the water injection pump truck 24, the injection main line 23, the first valve 22 and the injection flow and pressure measuring mechanism 11 constitute the injection system. The test liquid in the first storage tank 21 is pressurized by the water injection pump truck 24. The test liquid enters the wellbore of the injection well 10 and the cavity of the storage tank 50 through the injection main line 23, the first valve 22 and the wellhead of the injection well 10.

[0061] After injection, the test fluid enters the pore space inside the sediment 51 through the cavity of the storage tank 50, and flows to the wellbore of the test well 30 through seepage.

[0062] like Figure 1As shown, the inlet point of the test well 30 can be located on the side or bottom of the storage tank 50. In one embodiment, the bottom sediment connectivity test system of the old brine storage tank in the salt mine includes a second storage tank 41 and a second valve 42 connected in series. The second valve 42 is connected to the test well 30 through a discharge main line 43. The test liquid flows into the discharge main line 43 through the wellhead of the test well 30, and enters the second storage tank 41 through the second valve 42 to monitor the pressure and flow rate at the discharge end, while collecting the test liquid flowing out at the discharge end. The power for the entire process comes from the water injection pump truck 24. The discharge flow rate and pressure measuring mechanism 31 includes a pressure gauge and a flow meter installed at the wellhead of the test well 30. The first valve 22 and the second valve 42 can be gate valves.

[0063] Furthermore, the first storage tank 21 is connected to the second storage tank 41, and the test liquid in the second storage tank 41 can flow into the first storage tank 21 to achieve circulation, thereby realizing the recycling of the test liquid, saving resources and reducing testing costs.

[0064] Storage tank 50 is a gas storage tank or energy storage tank. The test liquid can be saturated brine. Injection well 10 can be an old well. Test well 30 can be a brine discharge well.

[0065] In one embodiment, the specific process of the method for testing the connectivity of sediment at the bottom of an old brine storage tank in a salt mine provided by the present invention includes:

[0066] (1) Fill the first storage tank 21 with saturated brine, the volume of which is at least 300 cubic meters; the storage volume of the second storage tank 41 is at least 300 cubic meters, and the second storage tank 41 must be empty before the test begins.

[0067] (2) According to Figure 1 The structure shown connects to the main discharge line 43 and installs the wellhead of the test well 30, along with a pressure gauge and flow meter.

[0068] (3) Pressure test the ground pipelines such as the main discharge line 43 to ensure that there is no spraying or leakage during the test;

[0069] (4) Before the test begins, release the pressure in the storage tank 50 cavity so that the pressure at the wellhead of injection well 10 is 0, and the excess brine can be reinjected into the first storage tank 21.

[0070] (5) At the start of the test, open the first valve 22, the second valve 42 and the wellhead valve on the connecting pipeline, and inject saturated brine into the storage tank 50 cavity through the water injection pump truck 24 until the flow rate at the discharge end of the test well 30 is stable.

[0071] (6) Increase the injection rate of injection well 10 to 40 cubic meters per hour, and inject for a period of time until the flow rate and pressure at the discharge end stabilize; after stabilization, test the pressure and flow rate of well 30 (i.e., the discharge end) and record them as P. L1 and Q L1 The pressure at the injection end is denoted as P. z1 ;

[0072] (7) Continue this process to increase the injection rate to 60, 80, 100, and 120 cubic meters per hour. (The pressure and flow rate at the wellhead of test well 30 corresponding to the injection rates of 60, 80, 100, and 120 cubic meters per hour are denoted as P respectively.) L2 Q L2 P L3 Q L3 (and so on)

[0073] (8) After the test with an injection rate of 120 cubic meters per hour is completed, close the wellhead valve of test well 30;

[0074] (9) After the fluidity test is completed, the maximum discharge flow rate test is started: continue to inject saturated brine into the wellhead of injection well 10. The injection process is carried out in a segmented pressurization manner. The specific process includes: taking the upper limit pressure of the storage tank 50 cavity as 4MPa as an example, if the wellhead pressure at the injection end is 1MPa after the fluidity test is completed (denoted as P) o1 Then, continue injecting saturated brine into the cavity until the pressure reaches 2 MPa (denoted as P). o2 After pressurizing, stop the injection valve, close the discharge valve, and open the discharge valve for 1 minute, recording the flow rate and pressure changes at the discharge end (denoted as P1 and Q1). Then, close the discharge valve, open the injection valve, and continue injecting saturated brine into the storage chamber 50 until it reaches 3 MPa. Stop pressurizing, close the injection valve, and open the discharge valve for 1 minute, recording the flow rate and pressure changes at the discharge end (denoted as P2 and Q2). Repeat the above steps until the upper pressure limit is reached. After the pressure reaches the upper pressure limit, close the injection well 10 wellhead, open the test well 30 wellhead, and test the final discharge flow rate (denoted as P). max Q max ).

[0075] Please fill in the above data in the table below:

[0076]

[0077] Table 1 Connectivity Test Experiment Data Recording Table

[0078] Experimental parameter analysis and screening were conducted.

[0079] P in the liquidity test L1 P L2 P L3…… and QL1 Q L2 Q L3…… Plot the corresponding curves for pressure and flow rate;

[0080] P in the maximum discharge flow test o1 P o2 P o3 ..., P1, P2, P3... P max And Q1, Q2, Q3...Q max Plot the curves corresponding to pressure and flow rate;

[0081] The two tests selected the injection pressure, discharge pressure, and flow rate that approached the maximum flow rate, denoted as Pz and P. L Q L Po, P, Q.

[0082] Then, the flow resistance is calculated:

[0083] (1) First, determine the fluid motion state, use the Reynolds number to distinguish different flow states, and calculate the drag coefficient according to the empirical formula for the drag coefficient. For details, please refer to Figure 4 The table showing the relationship between the empirical formula for drag coefficient and Reynolds number and flow pattern is provided.

[0084] (2) After the drag coefficient is determined, there are three cases based on the flow pattern:

[0085] a) Laminar flow:

[0086]

[0087]

[0088] b) Hydraulic smoothing:

[0089]

[0090] c) Hydraulic roughness:

[0091]

[0092] In the above formula: h f Let ρ be the pipe friction, λ be the coefficient of friction, l be the pipe length, v be the flow velocity, d be the pipe diameter, ρ be the fluid density, μ be the dynamic viscosity, and Q be the flow rate. denoted as roughness, and Δ as absolute roughness.

[0093] Based on the test data from step (9) above: P z P L Q L P oSubstituting P and Q into the above formula, the frictional resistance within the tubing string is calculated. Assuming the depth of test well 30 is h and the depth of the old well is H, other parameters in the frictional resistance calculation are substituted based on the actual parameters of the tubing string. The frictional resistances of test well 30 and the old well tubing string are calculated as h, h, and h, respectively. fc and h fl .

[0094] Then calculate the sediment friction M:

[0095] M = (P o -Ph fc1 )+(P z -h fl - h fc2 - P L )) / 2

[0096] The present invention provides a method for testing the connectivity of sediment at the bottom of an old brine storage tank in a salt mine. By using the method of water injection and brine return from the old well to the brine discharge well, the method tests the connectivity between the old well shaft, the storage tank 50 cavity, and the brine discharge well. It also tests the basic parameters such as porosity and flow resistance of the sediment 51 at the bottom, providing first-hand data for the utilization of sediment 51 and providing effective data support for subsequent gas injection, brine discharge, and cavity volume calculation.

[0097] Option 2

[0098] This invention provides a system for testing the connectivity of sediment at the bottom of old brine storage tanks in salt mines, applicable to the aforementioned method for testing the connectivity of sediment at the bottom of old brine storage tanks in salt mines. Figure 1 As shown, the system for testing the connectivity of sediment at the bottom of the old brine storage chamber in this salt mine includes:

[0099] Storage tank 50, with sediment 51 present at the bottom of the chamber;

[0100] Injection well 10 is connected to the top of storage tank 50, and injection flow and pressure measuring mechanism 11 is connected to the wellhead of injection well 10;

[0101] Test well 30 is connected to the side or bottom of storage tank 50, and the wellhead of test well 30 is connected to discharge flow and pressure measuring mechanism 31;

[0102] The test fluid injected into the storage tank 50 by the injection well 10 can flow through the sediment 51 at the bottom of the storage tank 50, then flow into the test well 30 and be discharged through the test well 30; the injection flow and pressure measuring mechanism 11 is used to measure the flow and pressure at the injection end, and the discharge flow and pressure measuring mechanism 31 is used to measure the flow and pressure at the discharge end.

[0103] This testing system can be used to conduct connectivity tests on the bottom sediment of the old brine storage tank in the salt mine. The test liquid can flow through the sediment 51 at the bottom of the storage tank 50 and then into the test well 30 and out. The test liquid is injected into the injection well 10 and returned from the test well 30 to test the connectivity between the injection well 10, the test well 30, the storage tank 50 and the sediment 51, as well as the physical properties of the sediment 51. It verifies the pore space and flow resistance of the bottom sediment 51, providing effective data support for subsequent gas injection and brine discharge and the calculation of the volume of the storage tank 50. It also facilitates the utilization of the sediment 51 formed by insoluble matter at the bottom of the storage tank 50, and significantly increases the usable storage capacity of the salt mine storage tank 50.

[0104] The above descriptions are merely a few embodiments of the present invention. Those skilled in the art can make various modifications or variations to the embodiments of the present invention based on the content disclosed in the application documents without departing from the spirit and scope of the present invention.

Claims

1. A method for testing the connectivity of sediment at the bottom of an old brine storage tank in a salt mine, characterized in that, A test system for the connectivity of sediment at the bottom of old brine storage tanks in salt mines was adopted. The system for testing the connectivity of sediment at the bottom of the old brine storage tank in the salt mine includes: A storage tank, the bottom of which contains sediment; An injection well is connected to the top of the storage tank, and the wellhead of the injection well is connected to an injection flow and pressure measuring mechanism. The test well is connected to the storage tank at a location located in the sediment area at the bottom of the storage tank, and the wellhead of the test well is connected to a discharge flow and pressure measuring mechanism. The method for testing the connectivity of the bottom sediment in the old brine storage tank of a salt mine includes: The test fluid injected into the storage tank by the injection well flows through the sediment at the bottom of the storage tank, then flows into the test well and is discharged through the test well. The injection flow and pressure measuring mechanism measures the flow and pressure at the injection end, and the discharge flow and pressure measuring mechanism measures the flow and pressure at the discharge end; The method for testing the connectivity of sediment at the bottom of the old brine storage tank in the salt mine includes a fluidity test, which includes: The injection well continuously injects test fluid into the storage tank at a first flow rate. After the flow rate and pressure at the discharge end stabilize, the flow rate and pressure at the discharge end, as well as the pressure at the injection end, are measured and recorded. The method for testing the connectivity of sediment at the bottom of the old brine storage tank in the salt mine includes a maximum discharge flow rate test, which includes: The test well is closed, and the test liquid is injected into the storage tank through the injection well until the pressure at the injection end is the first pressure; the injection well stops injecting the test liquid and is closed, the test well is opened, and the flow rate and pressure at the discharge end are measured and recorded.

2. The method for testing the connectivity of sediment at the bottom of an old brine storage tank in a salt mine according to claim 1, characterized in that, The liquidity test includes: After completing the first flow rate test, the flow rate value is gradually increased based on the first flow rate. The flow rate and pressure at the discharge end and the pressure at the injection end are measured and recorded after stabilization.

3. The method for testing the connectivity of sediment at the bottom of an old brine storage tank in a salt mine according to claim 1, characterized in that, The maximum discharge flow rate test includes: After the first pressure test is completed, the injection well continues to inject test fluid into the storage tank. The pressure is gradually increased from the first pressure to the upper limit pressure of the storage tank cavity using a segmented pressurization method. The flow rate and pressure at the discharge end are measured and recorded after the injection well is closed and the test well is opened.

4. The method for testing the connectivity of sediment at the bottom of an old brine storage tank in a salt mine according to claim 1, characterized in that, The maximum discharge flow rate test is performed after the fluidity test.

5. The method for testing the connectivity of sediment at the bottom of an old brine storage tank in a salt mine according to claim 4, characterized in that, Based on the flow rate and pressure at the injection end and the flow rate and pressure at the discharge end, calculate the frictional resistance of the test well tubing, the frictional resistance of the injection well tubing, and the sediment frictional resistance.

6. The method for testing the connectivity of sediment at the bottom of an old brine storage tank in a salt mine according to claim 1, characterized in that, The salt mine brine old storage chamber bottom sediment connectivity test system includes a first liquid storage tank, a water injection pump truck and a first valve connected in series. The first valve is connected to the injection well through the main injection pipeline.

7. The method for testing the connectivity of sediment at the bottom of an old brine storage tank in a salt mine according to claim 6, characterized in that, The salt mine brine old storage chamber bottom sediment connectivity test system includes a second storage tank and a second valve connected in series. The second valve is connected to the test well through the discharge main line.

8. The method for testing the connectivity of sediment at the bottom of an old brine storage tank in a salt mine according to claim 7, characterized in that, The first storage tank is connected to the second storage tank, and the test liquid in the second storage tank can flow into the first storage tank to achieve circulation.

9. A system for testing the connectivity of sediment at the bottom of an old brine storage tank in a salt mine, characterized in that, The method for testing the connectivity of sediment at the bottom of an old brine storage tank as described in any one of claims 1-8, wherein the testing system for the connectivity of sediment at the bottom of an old brine storage tank comprises: A storage tank, the bottom of which contains sediment; An injection well is connected to the top of the storage tank, and the wellhead of the injection well is connected to an injection flow and pressure measuring mechanism. A test well, which is connected to the side or bottom of the storage tank, and the wellhead of the test well is connected to a discharge flow and pressure measuring mechanism; The test fluid injected into the storage tank through the injection well can flow through the sediment at the bottom of the storage tank, then flow into the test well and be discharged through the test well; the injection flow and pressure measuring mechanism is used to measure the flow and pressure at the injection end, and the discharge flow and pressure measuring mechanism is used to measure the flow and pressure at the discharge end.

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