An underground soluble salt mining structure and method based on leakage recharge

Abstract

The present invention provides an underground soluble salt mining structure and method based on leakage recharge, belonging to the technical field of soluble salt mining, including a recharge channel well, a brine production well, a sealing assembly, and a connecting well. The connecting well is opened inside the soluble salt ore layer. The brine production well penetrates through the upper rock formation and extends into the soluble salt layer. When a confined aquifer is located above the soluble salt layer to form an upper confined aquifer, the recharge channel well penetrates through the upper rock formation and the upper confined aquifer and extends into the soluble salt ore layer. The present invention utilizes the pressure of the underground confined water itself, and through an artificial recharge channel, enables the underground confined water to enter the soluble salt layer, and then dissolves and mines the soluble salt. On the one hand, it solves the problem of insufficient surface fresh water volume, and on the other hand, by utilizing the advantage that the groundwater temperature is higher than that of surface water, it can improve the dissolution efficiency of soluble salt to a certain extent, and further improve the mining efficiency of soluble salt.

Description

Technical Field

[0001] The present invention belongs to the technical field of soluble salt mining, and particularly relates to an underground soluble salt mining structure and method based on leakage recharge. Background Art

[0002] Most of the exploitation of salt mineral resources adopts the solution mining process. This method utilizes the solubility of salt minerals, taking water as a solvent and injecting it into the ore deposit. Through physical and chemical reactions in the ore deposit, salt minerals are dissolved in situ and transformed into brine, and then collected and transported. To improve the efficiency of solution mining, for different ore geological conditions, a variety of methods have been widely applied, including brine lifting and pumping method, single-well convection method, well group connection method, etc. These methods have been widely used in the exploitation of salt deposits such as chlorides (rock salt, sylvite, carnallite, polyhalite), sulfates (anhydrite, mirabilite, glauberite), and carbonates (trona), achieving good technical and economic effects. However, in terms of current technology, the acquisition of solvent water is the core determining the effectiveness of this method. With the continuous tightening of relevant policies on ecological civilization construction, the utilization of surface water is increasingly restricted.

[0003] Currently, when mining soluble salts, the solvent water mainly comes from surface fresh water. By injecting surface fresh water into the ore-bearing layer, the soluble salts are dissolved and mined using surface fresh water. The consumption of surface fresh water is large and it has a great impact on the regional ecology. On the other hand, the temperature of surface water is relatively low, and its dissolving ability for soluble salts is poor, thus affecting the mining efficiency of soluble salts. Summary of the Invention

[0004] Aiming at the deficiencies of the above-mentioned existing technologies, the technical problem to be solved by the embodiments of the present invention is to provide an underground soluble salt mining structure and method based on leakage recharge.

[0005] To solve the above technical problems, the present invention provides the following technical solutions:

[0006] An underground soluble salt mining structure based on leakage recharge includes a recharge channel well, a brine production well, a sealing assembly, and a connecting well.

[0007] The connecting well is opened inside the soluble salt ore layer.

[0008] The brine production well penetrates the upper rock formation and extends into the soluble salt layer.

[0009] When the confined aquifer is located above the soluble salt layer to form an upper confined aquifer, the recharge channel well penetrates through the upper rock formation and the upper confined aquifer and extends into the soluble salt ore layer. One end of the connection well is connected to the recharge channel well, and the other end is connected to the brine production well. The sealing assembly is arranged in the recharge channel well inside the upper rock formation to prevent the confined water from gushing out from the upper port of the recharge channel well.

[0010] When the confined aquifer is located below the soluble salt layer to form a lower confined aquifer, the recharge channel well penetrates through the upper rock formation, the upper aquitard, the soluble salt layer and the lower aquitard in sequence and extends into the lower confined aquifer. One end of the connection well is connected to the recharge channel well, and the other end is connected to the brine production well. The sealing assembly is arranged at a position above the connection well inside the recharge channel well to prevent the confined water from gushing out from the upper port of the recharge channel well.

[0011] As a further improvement of the present invention: when the confined aquifer forms a lower confined aquifer below the soluble salt ore layer, a water-stop casing is arranged in the upper confined aquifer, and the water-stop casing is used to seal the brine production well.

[0012] As a further improvement of the present invention: the sealing assembly is a water-stop packer.

[0013] As a further improvement of the present invention: the connection well is of a horizontal structure.

[0014] As a further improvement of the present invention: the connection well is an open-hole completion.

[0015] As a further improvement of the present invention: the mining structure further includes a gas-driven pressure-compensating well, and the gas-driven pressure-compensating well penetrates through the upper rock formation and is connected to the confined aquifer.

[0016] A method for underground soluble salt mining based on leakage recharge includes the following steps:

[0017] 1) Construct a recharge channel well and a brine production well respectively on the upper rock formation on the surface of the mining area;

[0018] 2) Lower a water-stop casing into the aquifer section penetrated by the brine production well and block it;

[0019] 3) Construct a connection well in the soluble salt layer to connect one end of the connection well to the recharge channel well and the other end to the brine production well;

[0020] 4) Lower a sealing assembly into the recharge channel well to prevent the confined water from gushing upward;

[0021] 5) When the self-pressure of the confined water is insufficient, a gas-driven pressure-compensating well is constructed to connect the gas-driven pressure-compensating well with the confined water layer, and then gas drive is carried out at the wellhead to achieve the compensation of the pressure of the confined water.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] The present invention utilizes the self-pressure of the underground confined water. Through the artificial recharge channel, the underground confined water enters the soluble salt layer, and then the soluble salt is dissolved and mined. On the one hand, the problem of insufficient surface fresh water volume is solved. On the other hand, taking advantage of the fact that the temperature of groundwater is higher than that of surface water, the dissolution efficiency of soluble salt can be improved to a certain extent, and thus the mining efficiency of soluble salt is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a schematic structure of the present invention Figure 1 ;

[0025] Figure 2 is a schematic structure of the present invention Figure 2 ;

[0026] In the figure: 1 - upper rock stratum, 2 - upper confined water layer, 3 - upper water-resisting layer, 4 - soluble salt ore layer, 5 - lower water-resisting layer, 6 - lower confined water layer, 7 - bottom rock stratum, 8 - recharge channel well, 9 - brine production well, 10 - sealing assembly, 11 - water-stop casing, 12 - connecting well, 13 - gas-driven pressure-compensating well. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0027] The technical solutions of the present application will be further described in detail below in conjunction with the specific embodiments.

[0028] The embodiments of the present application are described in detail below. The examples of the embodiments are shown in the drawings, where the same or similar reference numerals represent the same or similar elements or elements with the same or similar functions from beginning to end. The embodiments described below with reference to the drawings are exemplary and are only used to explain the present application and should not be construed as a limitation to the present application.

[0029] Please refer to Figure 1 and Figure 2, this embodiment provides an underground soluble salt mining structure based on leakage recharge, including a recharge channel well 8, a brine production well 9, a sealing assembly 10, and a connecting well 12. The connecting well 12 is opened inside the soluble salt ore layer 4. The brine production well 9 penetrates the upper rock formation 1 and extends into the soluble salt layer 4. When the confined aquifer is above the soluble salt layer 4 and forms an upper confined aquifer 2, the recharge channel well 8 penetrates the upper rock formation 1 and the upper confined aquifer 2 and extends into the soluble salt ore layer 4. One end of the connecting well 12 is connected to the recharge channel well 8, and the other end is connected to the brine production well 9. The sealing assembly 10 is arranged in the recharge channel well 8 inside the upper rock formation 1 to prevent the confined water from gushing out from the upper port of the recharge channel well 8. When the confined aquifer is below the soluble salt layer 4 and forms a lower confined aquifer 6, the recharge channel well 8 penetrates the upper rock formation 1, the upper aquitard 3, the soluble salt layer 4, and the lower aquitard 5 in sequence and extends into the lower confined aquifer 6. One end of the connecting well 12 is connected to the recharge channel well 8, and the other end is connected to the brine production well 9. The sealing assembly 10 is arranged at the position above the connecting well 12 inside the recharge channel well 8 to prevent the confined water from gushing out from the upper port of the recharge channel well 8.

[0030] When the confined aquifer is above the soluble salt layer 4 and forms an upper confined aquifer 2, the confined water in the upper confined aquifer 2 flows downward along the recharge channel well 8 under its own pressure and enters the inside of the connecting well 12. When the confined water flows into the connecting well 12, it can continuously dissolve the soluble salt in the soluble salt ore layer 4. After reaching saturation, saturated brine is formed. The saturated brine enters the brine production well 9 and is finally mined to the surface.

[0031] When the confined aquifer is below the soluble salt layer 4 and forms a lower confined aquifer 6, the confined water in the lower confined aquifer 6 flows upward along the recharge channel well 8 under its own pressure and enters the inside of the connecting well 12. When the confined water flows into the connecting well 12, it can continuously dissolve the soluble salt in the soluble salt ore layer 4. After reaching saturation, saturated brine is formed. The saturated brine enters the brine production well 9 and is finally mined to the surface.

[0032] In the above process, the inner cavity of the recharge channel well 8 is sealed by the sealing assembly 10, so as to prevent the confined water from gushing out from the upper port of the recharge channel well 8, so that the confined water can only enter the inside of the soluble salt ore layer 4 and then dissolve the soluble salt.

[0033] Please refer to Figure 1 , in one embodiment, a water-stop casing 11 is arranged in the upper confined aquifer 2, and the water-stop casing 11 is used to seal the brine production well 9.

[0034] In one embodiment, the sealing assembly 10 is a water stop separator, the communication well 12 is a horizontal structure, and the communication well 12 is an open-hole completion.

[0035] Please refer to Figure 1 and Figure 2 , in one embodiment, the mining structure further includes a gas injection pressure compensation well 13, the gas injection pressure compensation well 13 penetrates through the upper rock formation 1 and communicates with the confined aquifer. When the self-pressure of the confined water is insufficient, the gas injection pressure compensation well 13 is constructed, and then gas injection is carried out through the wellhead to achieve the compensation of the pressure of the confined water, so that the groundwater can smoothly enter the soluble salt layer 4 from the recharge channel well 8, and the dissolution mining of the soluble salt is realized.

[0036] Please refer to Figure 1 and Figure 2 , in one embodiment, a bottom rock formation 7 is provided below the lower confined aquifer 6.

[0037] In one embodiment, a method for underground soluble salt mining based on leakage recharge is provided, and the method includes the following steps:

[0038] 1) Construct a recharge channel well 8 and a brine production well 9 respectively on the upper rock formation 1 on the surface of the mining area;

[0039] 2) Lower a water stop casing 11 into the aquifer section passed through by the brine production well 9 and block it;

[0040] 3) Construct a communication well 12 in the soluble salt layer 4, so that one end of the communication well 12 is communicated with the recharge channel well 8 and the other end is communicated with the brine production well 9;

[0041] 4) Lower a sealing assembly 10 into the recharge channel well 8 to prevent the confined water from gushing upward;

[0042] As described above, a set of systems for mining underground soluble salts using underground confined water is constructed. At this time, under the condition of the self-pressure of the confined water, the groundwater enters the communication well 12 in the soluble salt layer 4 from the recharge channel well 8. The communication well 12 is an open-hole completion. During the process of the underground water flowing through this section, the soluble salt is continuously dissolved. After reaching saturation, a saturated brine is formed and enters the brine production well 9, and finally is mined to the surface.

[0043] 5) When the self-pressure of the confined water is insufficient, construct a gas injection pressure compensation well 13 to connect the gas injection pressure compensation well 13 with the confined aquifer, and then carry out gas injection through the wellhead to achieve the compensation of the pressure of the confined water, so that the groundwater can smoothly enter the soluble salt layer 4 from the recharge channel well 8, and the dissolution mining of the soluble salt is realized.

[0044] The preferred embodiments of the present application have been described in detail above. However, the present application is not limited to the above embodiments, and various changes can be made without departing from the gist of the present application within the scope of knowledge possessed by those of ordinary skill in the art.

Claims

1. An underground soluble salt mining structure based on leakage recharge, characterized in that It includes a recharge channel well, a brine production well, a sealing assembly and a connecting well. The connecting well is drilled inside the soluble salt ore layer. The brine production well penetrates the upper rock formation and extends into the soluble salt ore layer. When the confined aquifer is located above the soluble salt ore layer to form an upper confined aquifer, the recharge channel well penetrates the upper rock formation and the upper confined aquifer and extends into the soluble salt ore layer. One end of the connecting well is connected to the recharge channel well, and the other end is connected to the brine production well. The sealing assembly is arranged in the recharge channel well inside the upper rock formation to prevent the confined water from gushing out from the upper port of the recharge channel well. When the confined aquifer is located below the soluble salt ore layer to form a lower confined aquifer, the recharge channel well penetrates the upper rock formation, the upper aquitard, the soluble salt ore layer and the lower aquitard in sequence and extends into the lower confined aquifer. One end of the connecting well is connected to the recharge channel well, and the other end is connected to the brine production well. The sealing assembly is arranged at the position above the connecting well in the recharge channel well to prevent the confined water from gushing out from the upper port of the recharge channel well. A water-stop casing is arranged in the upper confined aquifer, and the water-stop casing is used to seal the brine production well.

2. The underground soluble salt mining structure based on leakage recharge according to claim 1, characterized in that, The sealing assembly is a water-stop packer.

3. The underground soluble salt mining structure based on leakage recharge according to claim 1, characterized in that, The connecting well is of a horizontal structure.

4. A structure for underground soluble salt mining based on leakage recharge according to claim 1, characterized in that, The connecting well is completed with an open hole.

5. A soluble salt mining structure based on leakage recharge according to claim 1, characterized in that The mining structure further includes a gas-driven pressure compensation well, and the gas-driven pressure compensation well penetrates the upper rock formation and is connected to the confined aquifer.

6. A method for underground soluble salt mining based on leakage recharge, which adopts the underground soluble salt mining structure based on leakage recharge as described in any one of claims 1-5, and is characterized in that, It includes the following steps: 1) Construct a recharge channel well and a brine production well respectively on the upper rock formation on the surface of the mining area. 2) Lower a water-stop casing into the section of the brine production well passing through the aquifer and plug it. 3) Construct a connecting well in the soluble salt ore layer so that one end of the connecting well is connected to the recharge channel well and the other end is connected to the brine production well. 4) Lower a sealing assembly into the recharge channel well to prevent the confined water from gushing upward. 5) When the self-pressure of the confined water is insufficient, construct a gas-driven pressure compensation well to connect the gas-driven pressure compensation well to the confined aquifer, and then perform gas drive at the wellhead to realize the compensation of the pressure of the confined water.

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