Natural alkali mining method and natural alkali mining well

Abstract

The present invention discloses a trona mining method and a trona mining well, relating to the technical field of trona mining. The trona mining method comprises the following steps: drilling to form a mining well: vertically drilling from a first position on the surface to the ground to form a mining well; drilling to form an injection well: vertically drilling from a second position on the surface to the ground to form a vertical well section; using a directional drilling tool composed of a continuous tubing, a bottom hole power source, and a measurement while drilling system, starting from the bottom of the vertical well section, turning horizontally multiple times and drilling to form multiple horizontal sections connected end to end, wherein one end of a horizontal section formed by the last horizontal drilling is connected to the mining well; the vertical well section and the multiple horizontal sections form an injection well; mining trona: injecting water into the injection well and extracting brine from the mining well. The trona mining method and the trona mining well of the present invention can increase the mining area and mining efficiency, and are also more cost-effective.

Description

Technical Field

[0001] The present invention relates to the technical field of natural alkali mining, in particular to a natural alkali mining method and a natural alkali mining well. Background Art

[0002] Natural soda is an important chemical raw material required for industrial production and is widely used in the fields of food, chemical industry, animal husbandry, petroleum, textile, medicine, fire protection and metallurgy. At present, the main methods for mining salt deposits are single well convection method, hydraulic fracturing connecting well method and horizontal connecting well method, among which the most commonly used method is horizontal well connecting well mining. However, due to the technical limitations of the length of a single horizontal section, if the mining area needs to be increased, it is necessary to arrange multiple horizontal wells connected to the vertical well. Each additional horizontal well involves repeated drilling of the vertical well section, movement of the drilling equipment and other problems, which will further increase the drilling cost. Therefore, there is an urgent need for a natural soda mining method that can increase the mining area and mining efficiency and at a lower cost. Summary of the Invention

[0003] The object of the present invention is to provide a natural alkali mining method and a natural alkali mining well to solve the problems existing in the above-mentioned prior art, so as to increase the mining area and mining efficiency and at a lower cost.

[0004] To achieve the above object, the present invention provides the following solutions:

[0005] The present invention provides a natural alkali mining method, comprising the following steps:

[0006] Drilling to form a production well: drilling vertically from a first position on the surface to form a production well underground, the production well passing through the underground natural soda ore layer;

[0007] Drilling an injection well includes the following steps:

[0008] Drilling to form a vertical well section: drilling vertically from the second position on the surface to the underground to form a vertical well section;

[0009] Drilling to form a horizontal section: Using a directional drilling tool combined with coiled tubing, bottom hole power, and a measurement while drilling system, starting from the bottom of the vertical well section, turning multiple times to a horizontal direction and drilling to form multiple horizontal sections connected end to end. The directional drilling tool drills in opposite directions when drilling two adjacent horizontal sections. One end of the horizontal section formed by the last horizontal drilling is connected to the production well. The vertical well section and the multiple horizontal sections form the injection well.

[0010] Mining natural alkali: injecting water into the injection well and extracting brine from the mining well.

[0011] In some embodiments, the natural alkali mining step further includes: injecting 100° C. water into the injection well at an injection rate of 340-360 cubic meters per day and an injection pressure of not less than 25 MPa.

[0012] In some embodiments, the step of drilling to form a production well further includes the following steps: reserving a cement plug: reserving a cement plug 3m-5m thick at the bottom of the production well.

[0013] In some embodiments, the step of drilling to form a production well further includes the following steps: lowering surface casing: the production well is formed by multiple drilling operations, and during the first drilling, surface casing is lowered into the production well.

[0014] In some embodiments, after the step of running the surface casing, the method further includes: thermal insulation cement cementing: filling thermal insulation cement between the inner wall of the production well and the surface casing.

[0015] In some embodiments, after the step of running the surface casing, the method further includes: running a technical casing: running a technical casing into the surface casing, the technical casing having a screen section, and water in the injection well can pass through the screen section and enter the technical casing.

[0016] In some embodiments, after running the technical casing, the method further includes: providing an annular space between the technical casing and the surface casing, and filling the annular space with a heat insulating medium.

[0017] In some embodiments, the step of mining natural alkali further comprises: stopping water injection after a period of mining, injecting foamed cement into the injection well, and continuing water injection after the foamed cement solidifies.

[0018] In some embodiments, the directional drilling tool drills horizontally twice to form two horizontal sections.

[0019] The present invention also provides a natural alkali production well, comprising a production well and an injection well, wherein the production well extends vertically downward from a first position on the surface and passes through the natural alkali ore layer, and the injection well comprises a vertical well section and a plurality of horizontal sections connected end to end in sequence, wherein the vertical well section extends vertically downward from a second position on the surface, and each of the horizontal sections is located in the natural alkali ore layer, and one end of the horizontal section formed by the last horizontal drilling is connected to the production well.

[0020] Compared with the prior art, the present invention has achieved the following technical effects:

[0021] The trona mining method provided in this embodiment utilizes continuous directional drilling using a directional drilling tool that combines coiled tubing, downhole power, and a measurement-while-drilling system. This creates multiple, end-to-end, connected horizontal sections within the trona ore layer. Water is injected into the injection well to dissolve the trona ore layer, and brine containing trona is obtained from the mining well. Compared to mining methods that utilize only a single horizontal well, this mining method adds multiple horizontal sections within the trona ore layer, increasing the mining area and improving mining efficiency. Furthermore, in the prior art, if multiple horizontal wells are drilled from different starting points, a vertical well section is required for each horizontal well, which also involves the cost of transporting ground drilling equipment, resulting in high costs. The trona mining method of this embodiment utilizes a directional drilling tool for continuous drilling, eliminating the need for moving ground drilling equipment and repeated drilling of vertical well sections, reducing the number of wells drilled and significantly saving mining costs.

[0022] Furthermore, by filling insulating cement between the mining well and the surface casing, and filling insulating medium between the technical casing and the surface casing, the heat exchange between the mining well and the inside and outside is reduced, and crystallization due to temperature changes in the process of brine rising from the bottom of the well in the mining well is avoided.

[0023] Furthermore, by injecting high-temperature and high-pressure water into the injection well, natural soda can be better dissolved in water, effectively avoiding the negative impact of natural soda crystallization during the mining process on mining.

[0024] Furthermore, after a period of mining, in order to prevent the natural alkali ore layer from being mined out and collapsing, foamed cement is injected into the injection well. The foamed cement can provide support for the well wall to prevent collapse. Moreover, the gaps on the foamed cement can provide a flow channel for water injected in the later mining. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0026] Figure 1 A schematic structural diagram of a trona mining well drilled using the trona mining method according to some embodiments of the present invention;

[0027] In the figure: 1, production well; 2, injection well; 21, horizontal section; 22, vertical well section; 3, surface casing; 4, technical casing; 41, screen section; 5, insulating cement; 6, insulating medium; 7, insulating water pipe; 8, water pump. DETAILED DESCRIPTION

[0028] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0029] The object of the present invention is to provide a natural alkali mining method and a natural alkali mining well to solve the problems existing in the above-mentioned prior art, so as to increase the mining area and mining efficiency and at a lower cost.

[0030] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0031] Example 1

[0032] This embodiment provides a natural alkali mining method, such as Figure 1 As shown, the following steps are included:

[0033] Drilling to form a production well 1: vertically drilling from a first position on the surface to form a production well 1 underground, wherein the production well 1 passes through an underground natural soda ore layer;

[0034] Drilling to form injection well 2: includes the following steps:

[0035] Drilling to form a vertical well section 22: vertically drilling from a second position on the surface to the underground to form a vertical well section 22;

[0036] Drilling to form horizontal section 21: A directional drilling tool using a combination of coiled tubing, bottomhole power, and a measurement while drilling system starts from the bottom of the vertical well section 22, turns horizontally multiple times, and drills to form multiple horizontal sections 21 connected end to end. The directional drilling tool drills in opposite directions when drilling two adjacent horizontal sections 21. One end of the horizontal section 21 formed by the last horizontal drilling is connected to the production well 1. The vertical well section 22 and multiple horizontal sections 21 form the injection well 2.

[0037] Mining natural soda: inject water into injection well 2 and extract brine from mining well 1.

[0038] The trona mining method provided in this embodiment utilizes a directional drilling tool comprising a coiled tubing, bottomhole power, and a measurement while drilling system for continuous directional drilling. This tool forms multiple horizontal sections 21 connected end-to-end within the trona ore layer. Water is injected into the injection well 2 to dissolve the trona ore layer, and brine containing trona is obtained from the mining well 1. Compared to mining methods utilizing only a single horizontal well, this mining method adds multiple horizontal sections 21 within the trona ore layer, thereby increasing the mining area and improving mining efficiency. Furthermore, in the prior art, if multiple horizontal wells are drilled starting from multiple locations, a vertical well section must be drilled for each horizontal well, which also involves the cost of transporting ground drilling equipment, resulting in high costs. The trona mining method of this embodiment utilizes a directional drilling tool for continuous drilling, avoiding the problems of moving ground drilling equipment and repeatedly drilling vertical well sections, thereby reducing the number of wells drilled and significantly saving mining costs. Among them, an insulated water pipe 7 can be used to connect a water pump 8, and the water pump 8 can be sunk into the mining well 1 to extract brine; before drilling the mining well 1, vertical drilling can be performed in the direction of the maximum principal stress based on the ground stress test.

[0039] In one embodiment of this embodiment, the trona extraction step further includes injecting 100°C water into injection well 2 at a rate of 340-360 cubic meters per day and an injection pressure of no less than 25 MPa. Injecting high-temperature, high-pressure water into injection well 2 allows the trona to dissolve better in the water, effectively preventing the negative impact of trona crystallization during the extraction process.

[0040] In order to protect the bottom of the mining well 1, in one embodiment of the present invention, the step of drilling to form the mining well 1 also includes the following steps: reserving a cement plug: reserving a cement plug 3m-5m thick at the bottom of the mining well 1.

[0041] In one embodiment of this invention, the step of drilling to form the production well 1 further includes the following steps: running a surface casing: The production well 1 is formed by multiple sparging operations. During the first sparging operation, a surface casing 3 is run into the production well 1. The surface casing 3 protects the wellhead of the production well 1 and makes the wellhead of the production well 1 more stable.

[0042] In one embodiment of this embodiment, after running the surface casing 3, the process further includes: insulating cement cementing: filling the space between the inner wall of the production well 1 and the surface casing 3 with insulating cement 5. Because the top of the production well 1 is close to the surface, the temperature there differs from that at the bottom of the well, which can easily lower the brine temperature and cause trona precipitation. The insulating cement 5 acts as a thermal insulator, preventing the ambient temperature from lowering the brine temperature and causing trona precipitation.

[0043] In one embodiment of this embodiment, after running the surface casing 3, the process further includes running the technical casing 4: running the technical casing 4 within the surface casing 3. The technical casing 4 includes a screen section 41. The position of the screen section 41 corresponds to the position of the horizontal section 21 formed during the last horizontal drilling. Water from the injection well 2 can pass through the screen section 41 and enter the technical casing 4. The screen can filter large particles of impurities in the brine, improving the quality of the extracted natural soda. The surface casing 3 and the technical casing 4 are preferably secured using dedicated fixtures or clamps. An insulated water pipe 7 can be used to connect a water pump 8, which is then lowered into the technical casing 4 to extract the brine.

[0044] In one embodiment of this embodiment, after the technical casing 4 is lowered, an annular space is formed between the technical casing 4 and the surface casing 3, and a heat insulating medium 6 is filled into the annular space. The heat insulating medium 6 further insulates the top of the production well 1, thereby preventing the precipitation of trona from the brine.

[0045] In one embodiment of this embodiment, in the natural alkali mining step, it also includes: after a period of mining, stopping water injection, injecting foamed cement into the injection well 2, and continuing water injection after the foamed cement solidifies. After a period of water injection development, part of the natural alkali ore layer in the injection well 2 is mined and prone to collapse. At this time, the injected foamed cement can provide support for the well wall of the injection well 2 to prevent collapse. At the same time, the foamed cement has pores and can also provide a circulation channel for the water injected in subsequent mining. The time to stop water injection and inject foamed cement can be determined according to the formation conditions after exploring the formation.

[0046] In one implementation of this embodiment, the directional drill tool drills horizontally twice to form two horizontal sections 21 .

[0047] Example 2

[0048] This embodiment provides a natural alkali production well, such as Figure 1 As shown, it includes a production well 1 and an injection well 2. The production well 1 extends vertically downward from a first position on the surface and passes through the natural soda ash layer. The injection well 2 includes a vertical well section 22 and multiple horizontal sections 21 connected end to end. The vertical well section 22 extends vertically downward from a second position on the surface. Each horizontal section 21 is located in the natural soda ash layer. One end of the horizontal section 21 formed by the last horizontal drilling is connected to the production well 1.

[0049] Compared to the method of mining using only one horizontal well, the natural soda mining well provided in this embodiment adds multiple horizontal sections located within the natural soda ore layer, thereby increasing the mining area and improving mining efficiency. In addition, in the prior art, if multiple horizontal wells are drilled from multiple different locations, a vertical well section needs to be drilled for each horizontal well, which also involves the problem of transporting ground drilling equipment, which is costly. The natural soda mining method of this embodiment uses directional drilling tools for continuous drilling, which avoids the problems of moving ground drilling equipment and repeatedly drilling vertical well sections, reduces the number of drilling wells, and greatly saves mining costs. Among them, two horizontal sections 21 are preferably provided; each horizontal section 21 can be in the same depth of the formation or in formations of different depths.

[0050] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. A natural alkali mining method, characterized in that: The following steps are involved: Drilling to form a production well: drilling vertically from a first position on the surface to form a production well underground, the production well passing through the underground natural soda ore layer; Drilling an injection well includes the following steps: Drilling to form a vertical well section: drilling vertically from the second position on the surface to the underground to form a vertical well section; Drilling to form a horizontal section: Using a directional drilling tool combined with coiled tubing, bottom hole power, and a measurement while drilling system, starting from the bottom of the vertical well section, turning multiple times to a horizontal direction and drilling to form multiple horizontal sections connected end to end. The directional drilling tool drills in opposite directions when drilling two adjacent horizontal sections. One end of the horizontal section formed by the last horizontal drilling is connected to the production well. The vertical well section and the multiple horizontal sections form the injection well. Mining natural alkali: injecting water into the injection well and extracting brine from the mining well.

2. The natural alkali mining method according to claim 1, wherein: The step of mining natural alkali also includes: injecting 100°C water into the injection well, with an injection flow rate of 340-360 cubic meters per day and an injection pressure of not less than 25 MPa.

3. The natural alkali mining method according to claim 1, wherein: The step of drilling to form a production well also includes the following steps: reserving a cement plug: reserving a cement plug 3m-5m thick at the bottom of the production well.

4. The natural alkali mining method according to claim 2, wherein: In the step of drilling to form a production well, The method comprises the following steps: running a surface casing: the mining well is formed by drilling multiple times, and during the first drilling, a surface casing is run into the mining well.

5. The natural alkali mining method according to claim 4, wherein: After the step of running the surface casing, the method further includes: thermal insulation cement cementing: filling thermal insulation cement between the inner wall of the production well and the surface casing.

6. The natural alkali mining method according to claim 5, wherein: After the step of running the surface casing, the method further includes: running a technical casing: running a technical casing into the surface casing, wherein the technical casing has a screen section, and water in the injection well can pass through the screen section and enter the technical casing.

7. The natural alkali mining method according to claim 6, wherein: After the technical casing is lowered, the method further comprises: providing an annular space between the technical casing and the surface casing, and filling the annular space with a heat insulating medium.

8. The natural alkali mining method according to claim 1, wherein: The step of mining natural alkali also includes: after mining for a period of time, stopping water injection, injecting foamed cement into the injection well, and continuing water injection after the foamed cement solidifies.

9. The natural alkali mining method according to claim 1, wherein: The directional drilling tool drills horizontally twice to form two horizontal sections.

10. A natural alkali production well constructed by the natural alkali production method according to claim 1, characterized in that: It includes a production well and an injection well. The production well extends vertically downward from a first position on the surface and passes through the natural alkali ore layer. The injection well includes a vertical well section and multiple horizontal sections connected end to end. The vertical well section extends vertically downward from a second position on the surface. Each of the horizontal sections is located in the natural alkali ore layer. One end of the horizontal section formed by the last horizontal drilling is connected to the production well.

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