Method for increasing brine output of brine mining well in salt lake mining area

Abstract

The invention discloses a method for increasing brine output of brine mining wells in a salt lake mining area, which belongs to the technical field of brine mining and comprises the following steps: S1, arranging auxiliary wells in set intervals of the brine mining wells; s2, a wellhead of the auxiliary well is sealed, brine is injected into the auxiliary well, so that the brine in the auxiliary well reaches set pressure, and the brine injected into the auxiliary well carries debris in formation pores to enter the brine mining well through a falling funnel; s3, extracting the brine in the brine extraction well together with the debris; and S4, when the content of debris in the brine extracted by the brine extraction well is reduced to a set degree, stopping injecting the brine into the auxiliary well. According to the invention, the auxiliary wells are arranged around the brine mining well and the brine is injected into the auxiliary wells, so that the formation pores can be opened by using the pressure of the brine, and debris in the formation pores enters the brine mining well through the falling funnel, thereby increasing the brine output, improving the brine mining efficiency and reducing the production cost.

Description

Technical Field

[0001] The invention relates to the technical field of brine mining, and in particular to a method for increasing the brine output of a brine mining well in a salt lake mining area. Background Art

[0002] Potassium salt, as an indispensable fertilizer component in agricultural production, is of great significance for improving crop yield and quality. Salt lake brine is one of the main sources of raw materials for potash fertilizer production. Salt lake brine is mainly stored in the intercrystalline pores of salt sedimentary layers formed during the sedimentary evolution of salt lakes. Due to changes in the geological environment, these sedimentary layers have formed a complex sedimentary structure, including multiple salt sedimentary layers and clay debris sedimentary layers, which in turn constitute an aquifer group of upper potential brine aquifers and multiple lower confined brine aquifers. These aquifers show a trend of gradually decreasing intercrystalline pores, weakening hydraulic connections, and decreasing water richness from top to bottom, which poses a challenge to the exploitation of brine.

[0003] For salt lakes with deep brine strata that need to be drained, the traditional mining method mainly uses brine wells. However, with the long-term and large-scale extraction of underground brine, the brine water level continues to drop, and the upper water-rich potential brine strata are gradually exhausted, resulting in a continuous decline in the brine extraction capacity of the brine wells. In order to maintain production, it is necessary to increase the proportion of mining in the lower pressure brine strata. However, the lower pressure brine strata generally have low porosity and poor water richness, and their single well brine production capacity is much lower than that of the upper potential brine strata, which poses a severe challenge to potash fertilizer production.

[0004] The existing brine extraction system and mining methods are unable to cope with this challenge. Even if more brine wells are added to the current brine extraction system, it is difficult to maintain a large production scale due to the interference effect of the group of wells. At the same time, the substantial increase in infrastructure investment and production costs has further aggravated the pressure on potash fertilizer production.

[0005] Therefore, how to improve the brine output capacity of existing brine wells and explore more efficient and economically reasonable brine extraction methods has become a key issue that needs to be urgently addressed in the current potash fertilizer production field. Summary of the invention

[0006] The purpose of the present invention is to provide a method for increasing the brine output of brine wells in salt lake mining areas to solve the problems existing in the above-mentioned prior art. By setting auxiliary wells around the brine wells and injecting brine into the auxiliary wells, the pressure of the brine can be used to open the pores of the formation, and the debris in the pores of the formation can enter the brine well through a descending funnel, thereby increasing the brine output, improving the efficiency of brine mining, and reducing production costs.

[0007] To achieve the above object, the present invention provides the following solutions:

[0008] The present invention provides a method for increasing the brine output of a brine mining well in a salt lake mining area, comprising the following steps:

[0009] S1. Arrange auxiliary wells within the set spacing of brine wells;

[0010] S2, sealing the wellhead of the auxiliary well, injecting brine into the auxiliary well, so that the brine in the auxiliary well reaches a set pressure, and the brine injected into the auxiliary well carries the debris in the pores of the formation into the brine production well through the descending funnel;

[0011] S3, extracting the brine in the brine extraction well together with the debris;

[0012] S4. When the debris content in the brine extracted from the brine production well drops to a set level, the injection of brine into the auxiliary well is stopped.

[0013] In one embodiment, in step S1, the auxiliary well is arranged at a distance of 50m to 200m from the brine production well.

[0014] In one embodiment, in step S1, a plurality of groups of auxiliary wells are arranged around the brine production well, and steps S2 to S4 are performed on the auxiliary wells one by one.

[0015] In one embodiment, in step S2, the extracted brine comes from a brine delivery channel. The brine extracted from the brine extraction well is first transported to the brine delivery channel and then injected into the auxiliary well from the brine delivery channel.

[0016] In one embodiment, in step S2, a water injection pump is used to inject brine into the auxiliary well, the inlet end of the water injection pump is connected to the brine delivery channel through a suction pipe, and the outlet end of the water injection pump is connected to the auxiliary well through an injection pipe, and the injection pipe penetrates into the auxiliary well near the bottom of the well.

[0017] In one embodiment, the rated flow rate of the water injection pump is not less than 100m 3 / h.

[0018] In one embodiment, in step S2, the brine pressure in the auxiliary well is no more than 2 MPa.

[0019] In one embodiment, in step S4, when the content of debris in the brine extracted from the brine production well is less than 2%, the injection of brine into the auxiliary well is stopped.

[0020] In one embodiment, in step S1, the auxiliary well is entirely casingd, the casing comprising a screen tube and a solid tube, the screen tube is placed in the brine stratum section, the solid tube is placed in the impermeable stratum section, and the solid tube has no sieve holes.

[0021] In one embodiment, the sieve hole diameter of the sieve tube is not less than 1.5 cm, and the sieve hole porosity is not less than 20%.

[0022] Compared with the prior art, the present invention has achieved the following technical effects:

[0023] The present invention sets up auxiliary wells around the brine mining well and injects brine into the auxiliary wells, thereby utilizing the pressure of the brine to open the pores of the formation, and allowing the debris in the pores of the formation to enter the brine mining well through a descending funnel, thereby increasing the brine output of the brine mining well and improving the efficiency of brine mining, thereby reducing the infrastructure investment in salt lake mines, extending the service life of brine mining equipment, and reducing production costs, providing strong support for the sustainable development of potash fertilizer production, and improving the enterprise and social and economic benefits.

[0024] Other technical solutions included in the present invention can also achieve the following technical effects:

[0025] The present invention arranges multiple groups of auxiliary wells around the brine production well, injects brine into the auxiliary wells one by one, and extracts brine from the brine production wells while injecting brine, so that the brine in the stratum around the brine production well can be exploited more thoroughly, and the brine output of a single brine production well can be increased. At the same time, multiple auxiliary wells can repeatedly use the same set of water injection equipment to reduce production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] 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.

[0027] Figure 1 is a cross-sectional view of a brine extraction system in an embodiment of the present invention;

[0028] Figure 2 It is a plan view of the brine extraction system in an embodiment of the present invention;

[0029] Among them, 1. Submerged brine strata; 2. Pressurized brine strata; 3. Brine mining wells; 4. Auxiliary wells; 5. Submersible pumps; 6. Water injection pumps; 7. Suction pipes; 8. Water injection pipes; 9. Brine transfer channels; 10. Aquicludes. DETAILED DESCRIPTION

[0030] 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.

[0031] The purpose of the present invention is to provide a method for increasing the brine output of brine wells in salt lake mining areas to solve the problems existing in the prior art. By setting auxiliary wells around the brine wells and injecting brine into the auxiliary wells, the pressure of the brine can be used to open the pores of the formation, and the debris in the pores of the formation can enter the brine well through a descending funnel, thereby increasing the brine output, improving the efficiency of brine mining, and reducing production costs.

[0032] 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.

[0033] The present invention is applicable to brine mining in salt lake mining areas. The strata in the salt lake mining areas are characterized by brine strata and aquicludes 10 being distributed in an upper and lower interval. The brine strata are further divided into a potential brine stratum 1 and a pressure brine stratum 2. The potential brine stratum 1 refers to a brine stratum located at a shallower part of the brine deposit, and the pressure brine stratum 2 refers to a brine stratum located at a deeper part of the brine deposit. Figure 1 As shown, there are multiple pressurized brine strata 2 below the potential brine strata 1.

[0034] like Figure 1 and Figure 2 As shown, the present invention provides a method for increasing the brine output of brine mining wells in salt lake mining areas, which can be applied as follows Figure 1 and Figure 2 The brine extraction system shown includes a brine extraction well 3 and an auxiliary well 4 which is arranged at a certain distance from the brine extraction well 3. The auxiliary well 4 has a lower installation cost than the brine extraction well 3. The main function of the auxiliary well 4 is to inject brine.

[0035] The method for increasing the brine output of brine mining wells in salt lake mining areas comprises the following steps:

[0036] S1. Auxiliary wells 4 are arranged within the set spacing of the brine mining wells 3. The set spacing here can be reasonably set according to parameters such as the brine content in the brine ore layer and the pressure that the auxiliary wells 4 can withstand.

[0037] S2. After placing the water injection pipe 8 in the auxiliary well 4, seal the wellhead of the auxiliary well 4, and inject brine into the auxiliary well 4 so that the brine in the auxiliary well 4 reaches a set pressure, which is sufficient to drive the brine into the brine ore layer and open the formation pores under the action of pressure, so that the debris (salt debris, sand and clay, etc.) in the formation pores will be separated from the formation pores. The separated debris, carried by the injected brine, enters the brine production well 3 through the descending funnel (a funnel-shaped water level drop area formed around the brine production well 3 when the brine is extracted).

[0038] S3. The brine in the brine well 3 is extracted together with the debris. A submersible pump 5 can be used for extraction. The submersible pump 5 goes deep below the liquid level of the brine in the brine well 3. The extracted brine enters the brine storage pool or the brine delivery channel 9.

[0039] S4. When the debris content in the brine extracted from the brine well 3 is reduced to a set level, the injection of brine into the auxiliary well 4 is stopped. The set level mentioned here can be understood as the debris content being reduced to a certain level, or reduced to an undetectable level. At this time, the brine injected into the auxiliary well 4 can no longer carry the debris in the formation pores, or a greater pressure is required to increase the debris, and the bearing capacity of the auxiliary well 4 or the increased cost caused by the increased pressure are no longer suitable for continuation.

[0040] The present invention sets an auxiliary well 4 around the brine production well 3 and injects brine into the auxiliary well 4, so as to utilize the pressure of the brine to open the pores of the formation, and let the debris in the pores of the formation enter the brine production well 3 through the descending funnel, thereby increasing the brine output of the brine production well 3, improving the efficiency of brine extraction, reducing production costs, and providing strong support for the sustainable development of potash fertilizer production.

[0041] The present invention solves the problem that the brine output of the brine well 3 in the salt lake mining area decays too quickly, resulting in a mismatch between the brine output capacity of the brine well 3 and the brine production capacity of the equipment and the need to frequently replace the brine production equipment by increasing the brine output of the brine well 3, thereby extending the service life of the brine production equipment supporting the existing brine well 3.

[0042] In one embodiment, in step S1, the auxiliary well 4 is arranged at a distance of 50m to 200m from the brine production well 3. Within this range, a suitable injection pressure can be adopted (which can be within the bearing capacity of the auxiliary well 4 and can pass the injected brine from the auxiliary well 4 to the brine production well 3), and the salt debris in the brine ore layer can be relatively thoroughly mined, which has high economy and feasibility.

[0043] In one embodiment, in step S1, multiple groups of auxiliary wells 4 are arranged around the brine mining well 3, and the auxiliary wells 4 can be evenly distributed around the brine mining well 3, and steps S2 to S4 are performed one by one on the auxiliary wells 4. After brine is injected into all the auxiliary wells 4, the brine ore layer in the area around the brine mining well 3 can be penetrated, and the salt debris in the brine ore layer in the area can be completely taken, which can increase the brine output of a single brine mining well 3. At the same time, multiple auxiliary wells 4 can repeatedly use the same set of water injection equipment, thereby effectively reducing production costs.

[0044] Compared with other existing technologies, the present invention has the advantages that the auxiliary well 4 has low cost and the water injection pump 6 can be reused, and the cost of increasing the brine output of the brine well 3 is lower than the cost of adding a new brine well 3, which can achieve the effect of reducing the infrastructure investment in salt lake mines and improving the economic benefits of enterprises and society.

[0045] In one embodiment, in step S2, the extracted brine comes from the brine delivery channel 9, and the brine taken from the brine mining well 3 is first transported to the brine delivery channel 9 by the submersible pump 5, and then injected into the auxiliary well 4 by the brine delivery channel 9 under the action of the water injection pump 6. Therefore, the brine injected into the auxiliary well 4 is the brine with less brine content extracted from the brine mining well 3, and there is no need to increase the source of brine, and there is no need to increase long-distance transportation equipment to transport the brine for injection, which reduces the equipment investment. At the same time, because the brine injected is low-halogen brine instead of pure water, it itself has a certain brine content, and the brine content can be increased after passing through the brine ore layer. Therefore, when preparing salts later, it is brine with a higher brine content, which reduces the energy loss when preparing salts with brine with a lower brine content.

[0046] In one embodiment, in step S2, a water injection pump 6 is used to inject brine into the auxiliary well 4. The inlet end of the water injection pump 6 is connected to the brine delivery channel 9 through the suction pipe 7, and the outlet end of the water injection pump 6 is connected to the auxiliary well 4 through the water injection pipe 8. The water injection pump 6 is located on the ground, and the water injection pipe 8 penetrates into the position of the auxiliary well 4 close to the bottom of the well, so that the brine can be injected into the bottom of the well through the water injection pipe 8. The size of the formation pores gradually decreases from top to bottom, that is, the closer the formation pores are to the bottom of the well, the smaller they are. By deepening the water injection pipe 8 into the bottom of the well, the injection pressure of the formation pores at the depth of the bottom of the well can be increased. At this time, the closer to the bottom of the well, the greater the injection pressure, so that the injection pressure corresponds to the formation pores, that is, the smaller the formation pores are, the greater the injection pressure is, so that the brine can pass through the brine ore layer better, smoothly open the formation pores in the brine ore layer, and better mine the salt debris in the brine ore layer.

[0047] In one embodiment, the rated flow rate of the water injection pump 6 is not less than 100m 3 / h, to ensure that the auxiliary well 4 can be filled with brine and maintain the brine at a pressure that can penetrate the brine stratum.

[0048] In one embodiment, in step S2 , the brine pressure in the auxiliary well 4 is not greater than 2 MPa to prevent excessive pressure from fracturing the formation and causing pressure relief in the auxiliary well 4 .

[0049] In one embodiment, in step S4, when the debris content in the brine extracted from the brine production well 3 is less than 2%, the injection of brine into the auxiliary well 4 is stopped. Avoid the mismatch between the input (the cost of brine injection) and the output (the salts obtained from the brine) to improve efficiency. At this time, although the injection of brine into the auxiliary well 4 is stopped, the submersible pump 5 can still be used to obtain brine with a high brine content in the brine production well 3 until the brine content drops to a certain level. After all the auxiliary wells 4 have undergone the brine injection process and the content of the brine taken has dropped to a certain level, the working life of the brine production well 3 is about to end.

[0050] In one embodiment, in step S1, casing is placed under the entire section of the auxiliary well 4, and the casing includes a screen pipe and a solid pipe. The screen pipe is placed under the brine ore layer section to facilitate brine to enter the brine ore layer from the auxiliary well 4 through the screen pipe. A solid pipe is placed under the aquiclude 10 section, and the solid pipe has no screen holes to avoid pressure loss and damage to the aquiclude 10.

[0051] In one embodiment, the sieve hole diameter of the sieve pipe is not less than 1.5 cm, and the sieve hole porosity is not less than 20%, so that the brine can smoothly enter the brine ore layer, and at the same time, the auxiliary well 4 is prevented from collapsing.

[0052] The present invention innovatively applies the Terzaghi effective stress principle, arranges a low-cost auxiliary well 4, and uses a water injection pump 6 to inject pressurized brine into the auxiliary well 4. While increasing the formation pore water pressure, the debris filling in the formation pores is caused to shear and slide, and then the slipped debris is guided to flow into the brine production well 3 and be pumped out by the submersible pump 5, thereby achieving the effect of improving the pore size and pore connectivity of the target aquifer and increasing the brine output of the brine production well 3.

[0053] The present invention provides specific embodiments as follows:

[0054] Lop Nur Salt Lake is located in the eastern part of the Tarim Basin. The lake area is 115km long from north to south and 90km wide from east to west, with an area of ​​about 10,350km 2 , which is one of the largest dry salt lakes in the world. Luobei Mining Area is located in the north of Lop Nur Salt Lake. Guotou Xinjiang Lop Nur Potash Co., Ltd. currently owns the mining rights of Luobei Mining Area. Within the mining rights of Luobei Mining Area, there is a total of one underground potential brine ore layer 1, namely W1, and three underground pressurized brine ore layers 2, namely W2~W4. As mining continues, the static water level in the mining area drops by about 1m each year. Due to the thinning of the brine ore layer, the annual brine mining capacity of the single well of the brine mining well 3 decreases by 10%~15%. If the current product scale is to be maintained, it is necessary to continuously add new brine mining wells 3.

[0055] The present invention is applied in the mining area. A brine well 3 and three auxiliary wells 4 are drilled in the mining area. The three auxiliary wells 4 are evenly arranged around the brine well 3. The distance between each auxiliary well 4 and the brine well 3 is 100m. The wellheads of the auxiliary wells 4 are sealed to prevent the injected brine from spraying out. A rated flow of 200m 3 / h submersible pump 5, each auxiliary well 4 is installed near the surface of the ground with a rated flow of 100m 3 / h water injection pump 6. Start the water injection pump 6 and inject brine into the auxiliary well 4 at a pressure of 1.5MPa. The injected brine moves into the formation pores through the pores of the auxiliary well 4 wall, increasing the formation pore water pressure, reducing the effective stress of the debris (salt debris, sand and clay, etc.) in the formation pores and causing shear sliding. Synchronously start the submersible pump 5 to pump water. The brine injected into the auxiliary well 4 carries the debris in the pores into the brine mining well 3 through the descending funnel and is discharged from the brine mining well 3 by the submersible pump 5, thereby improving the pore size and pore connectivity of the brine stratum. Continue to inject brine into the auxiliary well 4 until the debris content of the brine taken from the brine mining well 3 is less than 2%. Repeat the above steps to inject brine into each auxiliary well 4. This embodiment increases the brine output of the brine mining well 3 by 36%.

[0056] 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 method for increasing the brine output of brine wells in a salt lake mining area, characterized in that: The following steps are involved: S1. Arrange auxiliary wells within the set spacing of brine wells; S2, sealing the wellhead of the auxiliary well, injecting brine into the auxiliary well, so that the brine in the auxiliary well reaches a set pressure, and the brine injected into the auxiliary well carries the debris in the pores of the formation into the brine production well through the descending funnel; S3, extracting the brine in the brine extraction well together with the debris; S4. When the debris content in the brine extracted from the brine production well drops to a set level, the injection of brine into the auxiliary well is stopped.

2. The method for increasing the brine output of brine mining wells in salt lake mining areas according to claim 1, characterized in that: In step S1, the auxiliary well is arranged at a distance of 50m to 200m from the brine production well.

3. The method for increasing the brine output of brine mining wells in salt lake mining areas according to claim 2, characterized in that: In step S1, a plurality of groups of auxiliary wells are arranged around the brine extraction well, and steps S2 to S4 are performed on the auxiliary wells one by one.

4. The method for increasing the brine output of brine mining wells in salt lake mining areas according to claim 1, characterized in that: In step S2, the extracted brine comes from the brine delivery channel. The brine extracted from the brine extraction well is first transported to the brine delivery channel and then injected into the auxiliary well by the brine delivery channel.

5. The method for increasing the brine output of brine mining wells in salt lake mining areas according to claim 4, characterized in that: In step S2, a water injection pump is used to inject brine into the auxiliary well. The inlet end of the water injection pump is connected to the brine delivery channel through a suction pipe, and the outlet end of the water injection pump is connected to the auxiliary well through an injection pipe. The injection pipe penetrates into a position close to the bottom of the auxiliary well.

6. The method for increasing the brine output of brine mining wells in salt lake mining areas according to claim 5, characterized in that: The rated flow rate of the water injection pump is not less than 100m 3 / h.

7. The method for increasing the brine output of brine mining wells in salt lake mining areas according to claim 6, characterized in that: In step S2, the brine pressure in the auxiliary well is not greater than 2 MPa.

8. The method for increasing the brine output of brine wells in salt lake mining areas according to claim 1, characterized in that: In step S4, when the content of debris in the brine extracted from the brine production well is less than 2%, the injection of brine into the auxiliary well is stopped.

9. The method for increasing the brine output of brine mining wells in salt lake mining areas according to claim 1, characterized in that: In step S1, casing is placed in the entire section of the auxiliary well, and the casing includes a screen tube and a solid pipe. The screen tube is placed in the brine ore layer section, and the solid pipe is placed in the impermeable layer section. The solid pipe has no screen holes.

10. The method for increasing the brine output of brine wells in salt lake mining areas according to claim 9, characterized in that: The sieve hole diameter of the sieve tube is not less than 1.5 cm, and the sieve hole porosity is not less than 20%.

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