Trona mining method and trona mining well

Abstract

The invention discloses a trona exploitation method and a trona exploitation well, and relates to the technical field of trona exploitation, the trona exploitation method comprises the following steps: drilling to form an exploitation well: vertically drilling from a first position of the earth surface to the underground to form the exploitation well; drilling to form an injection well: vertically drilling from a second position of the earth surface to the underground to form a straight well section; a directional drilling tool formed by combining a coiled tubing, well bottom power and a measurement-while-drilling system is adopted, the bottom of the vertical well section serves as a starting point, multiple times of turning is conducted to the horizontal direction, drilling is conducted to form a plurality of horizontal sections which are sequentially communicated end to end, and one end of the horizontal section formed by last-time horizontal drilling is communicated with the mining well; the straight well section and the horizontal sections form an injection well; and mining trona: injecting water into the injection well, and extracting brine from the mining well. According to the trona mining method and the trona mining well, the mining area can be increased, the mining efficiency can be improved, and the cost is lower.

Description

Technical Field

[0001] The 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 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 respectively. 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 has 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 natural alkali ore layer underground;

[0007] Drilling to form 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 that is a combination of a coiled tubing, a bottom hole power, and a measurement while drilling system, starting from the bottom of the vertical well section, turning to the horizontal direction for multiple times and drilling to form multiple horizontal sections that are connected end to end, the directional drilling tool has opposite drilling directions when drilling to form two adjacent horizontal sections, and one end of a horizontal section formed by the last horizontal drilling is connected to the production well; the vertical well section and 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, with 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 of 3m-5m thickness 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, a surface casing is lowered into the production well.

[0014] In some embodiments, after the step of lowering 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 lowering the surface casing, the step further includes: lowering a technical casing: lowering a technical casing into the surface casing, the technical casing having a screen section, and the water in the injection well can pass through the screen section and enter the technical casing.

[0016] In some embodiments, after the technical casing is lowered, the method further includes: an annular space is provided between the technical casing and the surface casing, and a heat insulating medium is filled into the annular space.

[0017] In some embodiments, in the step of mining natural alkali: it 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.

[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 a 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 natural alkali mining method provided in this embodiment performs continuous directional drilling through a directional drilling tool composed of a continuous oil pipe, bottom hole power and a measurement while drilling system, and forms multiple horizontal sections connected end to end in sequence in the natural alkali ore layer. The natural ore layer can be dissolved by injecting water into the injection well, and brine containing natural alkali can be obtained from the mining well. Compared with the method of mining using only one horizontal well, this mining method adds multiple horizontal sections located in the natural alkali ore layer, increases the mining area, and improves the mining efficiency; in addition, in the prior art, if multiple horizontal wells are formed by drilling from multiple different positions as starting points, each corresponding to a horizontal well needs to be drilled to form a vertical well section, and the problem of carrying ground drilling equipment is also involved, which is costly. The natural alkali mining method in this embodiment uses a directional drilling tool to continuously drill, which avoids the problems of moving the drilling equipment on the ground, repeatedly drilling the vertical well section, etc., reduces the number of drilling wells, and greatly saves 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 on mining during the mining process.

[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, and the gaps in 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 drawings required for use in the embodiments will be briefly introduced below. 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 creative work.

[0026] Figure 1 A schematic diagram of the structure of a natural alkali production well drilled by the natural alkali production method in 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 be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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 creative work 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] Embodiment 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: drilling vertically from a first position on the surface to form a production well 1 underground, and the production well 1 passes through the natural alkali ore layer underground;

[0034] Drilling to form an 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 a horizontal section 21: A directional drilling tool using a combination of a coiled tubing, a bottom hole power, and a measurement while drilling system takes the bottom of the vertical well section 22 as the starting point, turns to the horizontal direction for multiple times, and drills to form multiple horizontal sections 21 that are connected end to end. The directional drilling tool drills in opposite directions when drilling to form two adjacent horizontal sections 21. One end of a 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 an injection well 2;

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

[0038] The natural alkali mining method provided in this embodiment performs continuous directional drilling through a directional drilling tool composed of a continuous oil pipe, bottom hole power and a measurement while drilling system, and forms multiple horizontal sections 21 connected end to end in sequence in the natural alkali ore layer. The natural ore layer can be dissolved by injecting water into the injection well 2, and brine containing natural alkali can be obtained from the mining well 1. Compared with the method of mining using only one horizontal well, this mining method adds multiple horizontal sections 21 located in the natural alkali ore layer, increases the mining area, and improves the mining efficiency; in addition, in the prior art, if multiple horizontal wells are formed by drilling from multiple different positions as starting points, each corresponding to a horizontal well needs to be drilled to form a vertical well section, and the problem of transporting ground drilling equipment is also involved, which is costly. The natural alkali mining method in this embodiment uses a directional drilling tool to continuously drill, which avoids the problems of moving the drilling equipment on the ground, repeatedly drilling the vertical well section, etc., reduces the number of drilling wells, and greatly saves mining costs. Among them, the water pump 8 can be connected to the insulated water pipe 7, 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 carried out in the direction of the maximum principal stress according to the ground stress test.

[0039] In one embodiment of the present invention, the step of mining natural alkali further includes: injecting water at 100°C into the injection well 2, with an injection flow rate of 340-360 cubic meters per day and an injection pressure of not less than 25 MPa. By injecting high-temperature and high-pressure water into the injection well 2, the natural alkali can be better dissolved in the water, effectively avoiding the negative impact of crystallization of natural alkali on mining during the mining process.

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

[0041] In one implementation of this embodiment, the step of drilling to form the production well 1 further includes the following steps: lowering the surface casing: the production well 1 is formed by multiple drillings, and during the first drilling, the surface casing 3 is lowered into the production well 1. The surface casing 3 can protect the wellhead of the production well 1 and make the wellhead of the production well 1 more stable.

[0042] In one implementation of this embodiment, after the step of lowering the surface casing 3, it also includes: insulating cement cementing: filling the insulating cement 5 between the inner wall of the mining well 1 and the surface casing 3. Since the top of the mining well 1 is close to the surface, its temperature is different from the bottom temperature, which can easily reduce the temperature of the brine and cause the precipitation of natural alkali, and the insulating cement 5 can play a role in heat insulation, preventing the external temperature from reducing the temperature of the brine and causing the precipitation of natural alkali.

[0043] In one embodiment of the present embodiment, after the step of lowering the surface casing 3, the step further includes: lowering the technical casing: lowering the technical casing 4 into the surface casing 3, the technical casing 4 having a screen section 41, the position of the screen section 41 corresponds to the position of the horizontal section 21 formed by the last horizontal drilling, and the water injected into the 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 and improve the quality of the natural alkali produced. Among them, the surface casing 3 and the technical casing 4 are preferably fixed with dedicated fixings or clamps; the water pump 8 can be connected with an insulated water pipe 7, and the water pump 8 is sunk into the technical casing 4 to extract the brine.

[0044] In one embodiment of the present embodiment, after the technical casing 4 is lowered, the following steps are further performed: an annular space is provided 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 can further insulate the top of the mining well 1, thereby preventing the precipitation of natural alkali from the brine.

[0045] In one implementation of this embodiment, in the step of mining natural alkali: 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 avoid collapse. At the same time, the foamed cement has pores and can also provide a circulation channel for the water injected in subsequent mining. Among them, 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 performs horizontal drilling twice to form two horizontal sections 21 .

[0047] Embodiment 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 alkali ore layer. The injection well 2 includes a vertical well section 22 and a plurality of horizontal sections 21 connected end to end in sequence. The vertical well section 22 extends vertically downward from a second position on the surface. Each horizontal section 21 is located in the natural alkali ore layer. One end of the horizontal section 21 formed by the last horizontal drilling is connected to the production well 1.

[0049] Compared with the method of using only one horizontal well for mining, the natural alkali mining well provided in this embodiment adds multiple horizontal sections located in the natural alkali ore layer, thereby increasing the mining area and improving the mining efficiency. In addition, in the prior art, if multiple horizontal wells are drilled from multiple different positions as starting points, a vertical well section needs to be drilled for each horizontal well, and the problem of transporting the ground drilling equipment is also involved, which is costly. The natural alkali mining method in this embodiment uses a directional drilling tool for continuous drilling, which avoids the problems of moving the ground drilling equipment and repeatedly drilling the vertical well section, reduces the number of drillings, and greatly saves the mining cost. Among them, it is preferred that two horizontal sections 21 are provided; each horizontal section 21 can be in the same depth of the formation or in the formation 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 used to help understand the method and core ideas of the present invention. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood 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 natural alkali ore layer underground; Drilling to form 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 that is a combination of a coiled tubing, a bottom hole power, and a measurement while drilling system, starting from the bottom of the vertical well section, turning to the horizontal direction for multiple times and drilling to form multiple horizontal sections that are connected end to end, the directional drilling tool has opposite drilling directions when drilling to form two adjacent horizontal sections, and one end of a horizontal section formed by the last horizontal drilling is connected to the production well; the vertical well section and 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, characterized in that: 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, characterized in that: The drilling step to form a production well also includes the following steps: reserving a cement plug: reserving a cement plug with a thickness of 3m-5m at the bottom of the production well.

4. The natural alkali mining method according to claim 2, characterized in that: In the step of drilling to form a production well, The method comprises the following steps: lowering a surface casing: the mining well is formed by multiple drillings, and during the first drilling, a surface casing is lowered into the mining well.

5. The natural alkali mining method according to claim 4, characterized in that: After the step of lowering 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, characterized in that: After the step of lowering the surface casing, the method further includes lowering a technical casing: lowering 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, characterized in that: After the technical casing is lowered, the method further comprises: an annular space is provided between the technical casing and the surface casing, and a heat insulating medium is filled into the annular space.

8. The natural alkali mining method according to claim 1, characterized in that: In the step of mining natural alkali: it 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, characterized in that: The directional drilling tool drills horizontally twice to form two horizontal sections.

10. A natural alkali production well, 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 a natural alkali ore layer. The injection well includes a vertical well section and a plurality of horizontal sections connected end to end in sequence. 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.

Images