Salt lake type potassium lithium ore gas lift mining method and system based on horizontal well and vertical well linkage

Abstract

The invention relates to the technical field of mineral resource mining, and discloses a salt lake type potassium lithium ore gas lift mining method and system based on linkage of a horizontal well and a vertical well. A horizontal well is constructed on the shoreside of a salt lake, a horizontal section of the horizontal well is in butt joint with a vertical well underground to form a well pattern shaped like a Chinese character'chang ', compressed air is injected into the horizontal well to form a low-density gas-liquid mixture, meanwhile, a suction pump is arranged in the vertical well, and brine is cooperatively driven to be conveyed to a shoreside treatment station by means of the gas lift effect generated by suction negative pressure and the density difference of the gas-liquid mixture; the corresponding system comprises a vertical well, a horizontal well, a gas injection system, a lifting system and a brine conveying pipeline. According to the method, the energy consumption of brine mining is greatly reduced, the single well mining radius is enlarged, the mining efficiency is improved, the method is particularly suitable for mining of low-grade potassium-lithium ore with large salt lake water depth and poor ore-bearing layer permeability, and economic benefits and ecological benefits are both achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of mineral resource exploitation, and in particular to a salt lake type potassium-lithium mine gas lift exploitation method and system based on linkage of horizontal wells and vertical wells. BACKGROUND

[0002] Potassium is an indispensable core nutrient element for the growth and development of crops, and the stable supply of potassium fertilizer is of strategic significance to the guarantee of national food security. Lithium, as a key metal in the field of new energy, its resource guarantee is also related to the overall situation of the development of the new energy industry. China's potassium-lithium resources are special, and most of them are hosted in salt lake brine, with the typical representative being the salt lake group in the Qaidam Basin of Qinghai.

[0003] At present, the exploitation methods of domestic salt lake brine potassium-lithium mines mainly include "channel mining" and "vertical well mining". Among them, the "channel mining" technology needs to build large-scale salt fields in the salt lake area, and realize the grading concentration of brine and the enrichment of minerals through natural evaporation, but this method has obvious drawbacks: first, the land occupation is large, and a single salt field system occupies several square kilometers of land, resulting in serious waste of land resources; second, the evaporation efficiency is restricted by climate conditions, and in high-altitude and low-evaporation areas, the brine concentration period is as long as several months or even several years, and the exploitation efficiency is extremely low; third, the ecological environment is greatly disturbed, and the construction of salt fields will destroy the original ecological system of the salt lake, and the leakage of salt fields will easily cause the surrounding soil salinization.

[0004] "Vertical well mining" is a widely used technology, which drills vertical wells in the salt lake mining area, and lifts the brine to the ground by submersible pumps, and then transports it to the processing plant through pipelines. However, this technology has many technical bottlenecks when facing large water depth, low permeability, and low-grade ore-bearing layers: first, the low permeability of the ore-bearing layer slows down the brine supply, and the daily brine production of a single well is low, making it difficult to meet the needs of industrial production; second, the construction of vertical wells in the lake center area needs to build a water-based operation platform, and the supporting power supply and maintenance facilities cost a lot, and the construction cost of a single well is 3-5 times higher than that of a shore-based well; third, the submersible pump needs to overcome the large water depth and the gravity of the brine to realize lifting, resulting in high energy consumption, and the single well exploitation radius is usually less than 200 meters, making it difficult to form a large-scale exploitation network; fourth, for low-grade ore layers, the unit mineral exploitation cost of traditional vertical well mining is too high, and it lacks economic feasibility.

[0005] In the prior art, some fields try to apply gas lift technology to fluid exploitation, and there are also cases of using horizontal well technology for mineral resource development, but there is no technology that integrates horizontal well docking, gas lift effect, and pump suction and applies it to large water depth, low permeability salt lake potassium-lithium mine exploitation scenarios, so there is an urgent need to develop a new type of exploitation technology that is suitable for such special salt lake working conditions. SUMMARY

[0006] The present application aims to overcome the shortcomings of the prior art salt lake potassium lithium mine mining technology, and provides a salt lake type potassium lithium mine gas lift mining method and system based on horizontal well and vertical well linkage, which has low energy consumption, wide mining range, strong adaptability and small ecological disturbance, and realizes efficient and economic mining of salt lake potassium lithium mines with large water depth, low permeability and low grade.

[0007] To solve the above technical problems, the present application adopts the following technical solutions:

[0008] A salt lake type potassium lithium mine gas lift mining method based on horizontal well and vertical well linkage comprises the following steps:

[0009] S1: at least one vertical well is constructed in a salt lake mining area, the vertical well penetrates to a potassium lithium brine layer, a screen pipe is used for completion of a mineral-containing section, and the screen pipe hole diameter is 0.5-1 mm;

[0010] S2: a horizontal well is constructed on the shore of a salt lake, the horizontal well has a curvature radius of 80-120 m in a build-up section, a horizontal section extends in the potassium lithium brine layer and is precisely connected with the vertical well underground, the connection error is controlled within 5 cm, a screen pipe or a bare hole is used for completion of a connection area, and a brine mining channel is formed;

[0011] S3: compressed air with a pressure of 0.8-1.2 MPa is injected into the horizontal well through an air compressor, so that the compressed air is mixed with brine to form a gas-liquid mixture with a density of 0.6-0.8 g / cm3;

[0012] S4: a submersible brine pump is lowered into the vertical well, a pump suction inlet is arranged at the bottom or lower part of the vertical well, and is 0.5-1 m away from the bottom plate of the potassium lithium brine layer;

[0013] S5: the submersible brine pump is started and compressed air is continuously injected, the submersible brine pump generates a negative pressure of-0.2--0.3 MPa at the bottom of the vertical well, the gas-liquid mixture and pure brine form a gas lift thrust due to a density difference, and the two cooperate to mine the potassium lithium brine from the vertical well to the shore through the horizontal well.

[0014] As a further scheme of the present application, in step S2, the horizontal section length of the horizontal well is 1000-1500 m, and 2-5 vertical wells can be connected to form a brine mining network.

[0015] As a further scheme of the present application, in step S3, the air injection amount of the air compressor can be dynamically adjusted according to the brine flow to ensure that the density of the gas-liquid mixture is stably kept at 0.6-0.8 g / cm3.

[0016] A salt lake type potassium lithium mine gas lift mining system comprises:

[0017] Vertical well unit, at least one vertical well, is arranged in the salt lake mining area and penetrates the potassium lithium brine layer, the ore-bearing section is a screen pipe completion structure, and a suction pump mounting position is arranged at the bottom of the well;

[0018] Horizontal well unit, one horizontal well, is arranged on the shore of the salt lake, and the horizontal section extends in the potassium lithium brine layer and is precisely connected with the vertical well, and the length of the horizontal section is 1000-1500 m;

[0019] Gas injection system, comprising an air compressor and an injection pipeline, the air compressor is arranged on the shore and the outlet pressure is adjustable, and the injection pipeline is connected with the air compressor and the wellhead of the horizontal well;

[0020] Lifting system, comprising a submerged brine electric pump, a cable and a control module, the submerged brine electric pump is arranged at the bottom of the vertical well, the cable is connected with the submerged brine electric pump and the shore power supply, and the control module can adjust the power of the submerged brine electric pump; brine conveying pipeline is connected with the wellhead of the horizontal well and the brine treatment facility on the shore, and the inner wall of the pipeline is treated for corrosion resistance.

[0021] As a further scheme of the present application, the air compressor of the gas injection system can operate in parallel to meet the gas injection demand of the multi-vertical well connection working condition.

[0022] As a further scheme of the present application, the control module of the lifting system can realize linkage control of the submerged brine electric pump and the air compressor, and guarantee the stable operation of the brine mining system.

[0023] The present application has the following technical effects compared with the prior art:

[0024] The present application realizes the synergistic lifting of the gas lifting effect and the suction pump, the required lift of the suction pump is reduced by 40%-50%, the daily average power consumption of a single well is reduced by more than 30% compared with the traditional vertical well mining, and the brine mining energy consumption cost is greatly reduced.

[0025] The length of the horizontal section of the horizontal well of the present application can reach kilometers, a single horizontal well can be connected with 2-5 vertical wells, forming a "one main and multiple auxiliary" brine mining network, the mining radius of a single well is expanded from less than 200 m to 1500 m, and the overall mining efficiency is improved by 2-3 times.

[0026] In the present application, the core equipment (air compressor, control module and treatment plant) is arranged on the shore, and it is not necessary to construct a costly water operation platform and power supply system in the lake center, the construction cost of a single set of mining system is reduced by 25%-30%, and the equipment maintenance convenience is greatly improved.

[0027] The present application reduces the engineering construction in the lake center area, avoids the construction of a large-scale salt field, reduces the disturbance to the original ecological system of the salt lake to the minimum, and reduces the risk of soil salinization caused by brine leakage.

[0028] The synergistic lifting method in this invention can effectively drive the flow of brine in low-permeability ore layers, solving the problem of uneconomical mining of low-grade ore using traditional methods and expanding the exploitable resource range of salt lake potassium-lithium ore. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the mining system in this invention;

[0030] In the diagram, 1-vertical well, 2-horizontal well, 3-potassium brine layer, 4-suction pump, 5-air compressor, 6-brine treatment plant. Detailed Implementation

[0031] 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.

[0032] Gas lift extraction method for saline lake-type potash and lithium deposits based on the linkage of horizontal and vertical wells

[0033] Vertical well construction: In the center of the salt lake or the main mining area, at least one vertical well shall be constructed. The drilling depth shall penetrate to the target potassium-lithium brine layer, and the bottom of the vertical well shall extend to the middle and lower part of the mineral brine layer to ensure the stability of brine replenishment. When completing the vertical well, screen pipe completion shall be used in the mineral brine layer section. The screen pipe pore diameter shall be controlled at 0.5~1mm to ensure smooth brine flow and intercept large-diameter impurities in the brine.

[0034] Horizontal well construction and downhole connection: A horizontal well is constructed in a flat area on the shore of the salt lake. The horizontal well is first drilled vertically to the preset depth and then the inclination section is started. The curvature radius of the inclination section is controlled at 80~120m to ensure well wall stability. The horizontal section needs to precisely pass through the potassium-lithium brine layer. The length of the horizontal section is set according to the mining requirements and can be extended up to 1500m. Through directional drilling technology, the horizontal section of the horizontal well and the vertical well are precisely connected in the potassium-lithium brine layer. The connection error is controlled within 5cm to form a downhole brine extraction channel. The connection area adopts open hole or screen pipe completion to ensure the flow of brine between the vertical well and the horizontal well.

[0035] Air injection to prepare low-density gas-liquid mixture: A compressor is arranged on the shore as an air injection device, and compressed air is continuously injected into the horizontal well through the injection pipeline. The pressure of the compressed air is controlled at 0.8-1.2 MPa, and the air injection amount is dynamically adjusted according to the brine flow rate to ensure that the air and the brine in the horizontal well are fully mixed to form a low-density gas-liquid mixture with a density of 0.6-0.8 g / cm³, which is significantly lower than that of pure brine (1.2-1.3 g / cm³).

[0036] Suction pump lowering: A suction pump, preferably a submersible brine pump, is lowered into the vertical well. The suction inlet of the pump is placed at the bottom or lower part of the vertical well, and is 0.5-1 m away from the bottom of the brine layer containing potassium and lithium, to ensure that high-concentration potassium and lithium-containing brine can be extracted. A cable and a control module are provided for the suction pump to accurately control the power of the pump.

[0037] Synergistic lifting of brine extraction: The suction pump is started and the continuous injection of compressed air is maintained. The suction pump generates a negative pressure of-0.2 to-0.3 MPa at the bottom of the vertical well, forming a suction force. At the same time, the low-density gas-liquid mixture in the horizontal well and the pure brine in the vertical well form a density difference in the U-shaped communication well network, generating an air-lifting thrust. The two forces synergistically drive the potassium and lithium-containing brine from the vertical well to flow into the horizontal well through the downhole docking channel, and finally to the shore brine treatment station.

[0038] Salt lake type potassium and lithium mine air-lifting exploitation system

[0039] Vertical well unit: at least one vertical well is arranged in the salt lake mining area and penetrates the potassium and lithium-containing brine layer. The mineralized section is completed with a screen pipe, and a suction pump installation site is provided at the bottom of the well for collecting mineralized brine.

[0040] Horizontal well unit: a horizontal well is arranged on the shore of the salt lake. The horizontal section extends into the potassium and lithium-containing brine layer and precisely docks with the vertical well. The length of the horizontal section can cover a mining range of 1000-1500 m, providing a channel for brine transportation.

[0041] Air injection system: including a compressor and an injection pipeline. The compressor is arranged on the shore, and the outlet pressure is adjustable. One end of the injection pipeline is connected to the compressor, and the other end extends to the wellhead of the horizontal well for transporting compressed air to the horizontal well.

[0042] Lifting system: including a suction pump, a cable, and a control module. The suction pump is a submersible brine pump placed at the bottom of the vertical well. The cable is used to transmit power, and the control module can start and stop the suction pump and adjust the power to form a negative pressure at the bottom of the vertical well.

[0043] Brine transportation pipeline: connected between the wellhead of the horizontal well and the shore brine treatment facility. The inner wall of the pipeline is treated for corrosion prevention, and is used to transport the extracted potassium and lithium-containing brine to the treatment end.

[0044] Example 1 Single vertical well docking horizontal well mining

[0045] A certain salt lake in Qinghai (water depth above the lake bottom 8m, permeability of potassium lithium brine layer 0.01~0.05mD, belongs to low permeability and low grade ore layer) implements the mining method of the application:

[0046] A vertical well is constructed in the center area of the salt lake, the drilling depth is 120m, and the potassium lithium brine layer section is 80~110m, which adopts a screen pipe with a pore diameter of 0.8mm for completion;

[0047] A horizontal well is constructed on the shore of the salt lake, the curvature radius of the build-up section is 100m, the length of the horizontal section is 1000m, and it precisely passes through the 80~110m potassium lithium brine layer and docks with the vertical well, the docking error is 0.3m, and the docking area adopts open hole completion;

[0048] A 150kW air compressor is configured on the shore, and compressed air with a pressure of 1.0MPa is injected into the horizontal well through the injection pipeline, the injection amount is controlled at 50m³ / min, and the gas-liquid mixture with a density of 0.7g / cm³ is formed by mixing with the brine;

[0049] A 200kW sub-halogen electric pump is lowered into the vertical well, and the pump suction inlet is 0.8m away from the brine layer bottom plate;

[0050] Start the sub-halogen electric pump and the air compressor, the sub-halogen electric pump generates-0.25MPa negative pressure at the bottom of the well, the density difference between the gas-liquid mixture and the pure brine forms gas lift thrust, and the two cooperate to drive the brine to flow, the daily average brine production of a single well reaches 800m³, which is 2.2 times higher than that of the traditional vertical well mining, and the daily average power consumption of a single well is reduced by 35% compared with the traditional way.

[0051] Example 2 Multi-vertical well docking horizontal well mining

[0052] A multi-vertical well docking scheme is implemented in a certain salt lake in Xinjiang (water depth above the lake bottom 12m, permeability of potassium lithium brine layer 0.02~0.06mD):

[0053] Three vertical wells are uniformly arranged in the salt lake mining area, the well spacing is 500m, and they all penetrate the 100~130m potassium lithium brine layer, and the ore-bearing section adopts a 1mm pore screen pipe for completion;

[0054] A horizontal well is constructed on the shore, the length of the horizontal section is 1500m, and it precisely docks with the three vertical wells in the 100~130m brine layer, and the docking error is controlled within 0.5m;

[0055] Two 200kW air compressors are configured in parallel operation, and compressed air with a pressure of 1.2MPa and a total injection amount of 80m³ / min is injected into the horizontal well, forming a gas-liquid mixture with a density of 0.65g / cm³;

[0056] 3 vertical wells are lowered into 200kW submersible halogen electric pump, and the pump suction inlet is 1m away from the halite layer bottom plate;

[0057] Synchronously start all equipment, and-0.3MPa negative pressure is formed at the bottom of the 3 vertical wells, which cooperates with the gas lift thrust, the daily halite production of the whole system reaches 2200m³, realizes large-scale efficient exploitation, and the unit halite power consumption is reduced by 40% compared with the traditional way.

[0058] The present application cooperates with the lifting of the suction pump by the gas lift effect, and the required head of the suction pump is reduced by 40%~50%, the daily power consumption of a single well is reduced by more than 30% compared with the traditional vertical well exploitation, and the halite energy consumption cost is greatly reduced.

[0059] The horizontal section length of the horizontal well of the present application can reach kilometers, and a single horizontal well can be connected with 2~5 vertical wells to form a halite mining network of ''one main and multiple auxiliary'', the single well exploitation radius is expanded from less than 200m to 1500m, and the overall exploitation efficiency is improved by 2~3 times.

[0060] The core equipment (air compressor, control module, processing plant) in the present application is arranged on the shore, and there is no need to build expensive water operation platform and power supply system in the lake center, the construction cost of a single set of mining system is reduced by 25%~30%, and the equipment maintenance convenience is greatly improved.

[0061] The present application reduces the engineering construction in the lake center, avoids the construction of large-scale salt field, reduces the disturbance to the original ecological system of the salt lake to the minimum, and reduces the risk of soil salinization caused by brine leakage.

[0062] The cooperative lifting mode in the present application can effectively drive the flow of brine in low permeability ore layer, solve the problem of uneconomical exploitation of low-grade ore in the traditional way, and expand the exploitable resource range of salt lake potassium and lithium ore.

[0063] The above is only the preferred embodiment of the present application, and does not limit the technical scope of the present application, so any slight modification, equivalent change and modification of the above embodiment according to the technical essence of the present application still belongs to the scope of the technical solution of the present application.

Claims

1. A gas lift extraction method for saline lake-type potash and lithium deposits based on the linkage of horizontal and vertical wells, characterized in that, Includes the following steps: S1: Construct at least one vertical well in the salt lake mining area, the vertical well penetrating to the potassium- and lithium-bearing brine layer, and use screen pipe completion in the ore-bearing section, with a screen pipe pore diameter of 0.5~1mm; S2: Construct a horizontal well on the shore of the salt lake. The curvature radius of the horizontal well's directional section is 80-120m. The horizontal section extends within the potassium-lithium brine layer and precisely connects with the vertical well underground. The connection error is controlled within 5cm. The connection area uses screen pipe or open hole completion to form a brine extraction channel. S3: Compressed air at a pressure of 0.8~1.2MPa is injected into the horizontal well using an air compressor, so that it mixes with the brine to form a gas-liquid mixture with a density of 0.6~0.8g / cm³; S4: A submersible brine pump is lowered into the vertical well, with the pump inlet located at the bottom or lower part of the vertical well and 0.5~1m away from the bottom plate of the potassium-lithium brine layer; S5: Start the submerged brine electric pump and continuously inject compressed air. The submerged brine electric pump generates a negative pressure of -0.2~-0.3MPa at the bottom of the vertical well. The gas-liquid mixture and the pure brine form a density difference to generate air lift thrust. The two work together to extract potassium-lithium brine from the vertical well to the shore through the horizontal well.

2. The gas lift extraction method for saline lake-type potash and lithium deposits based on the linkage of horizontal and vertical wells as described in claim 1, characterized in that, In step S2, the horizontal section of the horizontal well has a length of 1000~1500m and can be connected to 2~5 vertical wells to form a brine extraction network.

3. The gas lift extraction method for saline lake-type potash and lithium deposits based on the linkage of horizontal and vertical wells as described in claim 1, characterized in that, In step S3, the air injection volume of the air compressor can be dynamically adjusted according to the brine flow rate to ensure that the density of the gas-liquid mixture is stable at 0.6~0.8 g / cm³.

4. A gas lift mining system for saline lake-type potash and lithium deposits to implement the method of any one of claims 1-3, characterized in that, include: A vertical well unit consists of at least one vertical well located in a salt lake mining area and penetrating a potassium- and lithium-bearing brine layer. The ore-bearing section has a screen pipe completion structure, and a suction pump installation position is provided at the bottom of the well. The horizontal well unit consists of a single horizontal well located on the shore of the salt lake. Its horizontal section extends within the potassium- and lithium-containing brine layer and precisely connects with the vertical well. The length of the horizontal section is 1000-1500m. The gas injection system includes an air compressor and an injection pipeline. The air compressor is located on the shore and has an adjustable outlet pressure. The injection pipeline connects the air compressor to the wellhead of the horizontal well. The lifting system includes a submerged brine pump, a cable, and a control module. The submerged brine pump is located at the bottom of the vertical well, the cable connects the submerged brine pump to the shore power supply, and the control module can adjust the power of the submerged brine pump. The brine delivery pipeline connects the wellhead of the horizontal well to the shore brine treatment facility, and the inner wall of the pipeline is treated with anti-corrosion coating.

5. The gas lift mining system for saline lake-type potassium-lithium ore according to claim 4, characterized in that, The air compressors of the gas injection system can be operated in parallel by multiple units to meet the gas injection requirements of multiple vertical well docking conditions.

6. The gas lift mining system for salt lake-type potash and lithium deposits according to claim 4, characterized in that, The control module of the lifting system can realize the linkage regulation of the submerged brine electric pump and the air compressor to ensure the stable operation of the brine extraction system.

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