阅读说明：本技术 一种层状盐岩选择性溶采造腔控制工艺 (Control process for selective solution mining cavity construction of layered rock salt ) 是由 李行 刘凯 许�鹏 张文广 卢青峰 付星辉 郝金波 于 2018-07-25 设计创作，主要内容包括：本发明涉及一种层状盐岩选择性溶采造腔控制工艺,具体是在盐穴储库建造过程中,首先,在钻井阶段对夹层进行钻孔压裂,在一定范围内破坏夹层的完整性；其次,在盐岩开采过程中,对夹层的上、下盐层先溶蚀造腔,使夹层长期处于卤水浸泡中；同时,改变注井水溶液的成分,使夹层中部分物质优先溶解,破坏夹层结构；另外,通过自振空化射流装置,调节井下注水方向和注水压力,加大对夹层的冲蚀作用,进一步促进夹层的快速剥蚀垮塌。本发明针对不同的盐岩层位,采取不同的开采方案,解决了层状盐岩中的厚夹层难以垮塌的问题,实现了盐穴储库溶腔形状的有效控制。(The invention relates to a layered salt rock selective solution mining cavity-building control process, which is characterized in that in the salt cavern reservoir building process, firstly, drilling and fracturing are carried out on an interlayer in a drilling stage, and the integrity of the interlayer is damaged within a certain range; secondly, in the process of salt rock mining, the upper salt layer and the lower salt layer of the interlayer are firstly corroded to form a cavity, so that the interlayer is soaked in brine for a long time; meanwhile, the components of the well injection water solution are changed, so that part of substances in the interlayer are dissolved preferentially, and the interlayer structure is damaged; in addition, the underground water injection direction and the water injection pressure are adjusted through the self-vibration cavitation jet device, the erosion effect on the interlayer is increased, and the rapid denudation and collapse of the interlayer are further promoted. The invention adopts different mining schemes aiming at different salt rock positions, solves the problem that a thick interlayer in the layered salt rock is difficult to collapse, and realizes the effective control of the shape of the dissolving cavity of the salt cavern reservoir.)

1. A layered rock salt selective solution mining cavity-making control process comprises the following steps:

(1) in the drilling stage, firstly, drilling to the bottom of the rock salt;

(2) on the basis of identifying the thickness and the position of the interlayer, forming a hole seam in the thick interlayer in the salt rock within a certain range through a physical action;

(3) after the thick interlayer hole seams are formed, mining a salt layer at the lower part of the thick interlayer; injecting diesel oil into the salt well, controlling the dissolution of the dissolution cavity, enlarging the diameter of the dissolution cavity at the lower part, suspending the interlayer and providing a space for the interlayer to collapse;

(4) adjusting the position of a casing opening of the salt well, and mining a salt layer on the upper part of the thick interlayer; controlling the dissolution of the dissolution cavity by adopting an oil pad method; a self-vibration cavitation jet device is additionally arranged at the lower part of the water injection pipe, the underground water injection direction is adjusted to be the horizontal direction, the water injection pressure is adjusted to be 6-12 MPa, and the erosion of the cavity in the horizontal direction is accelerated;

(5) adjusting the opening of the underground water injection pipe to the thick interlayer, directly eroding the thick interlayer by using a self-vibration cavitation jet device, and further promoting the erosion and the peeling of the thick interlayer, wherein a certain amount of chemical substances for accelerating the erosion of interlayer substances are optionally added into the water solution of the injection well;

(6) after the thick interlayer collapses, controlling the upward dissolution by using an oil pad, and continuously exploiting an upper salt layer; and adjusting the underground water injection direction to be the horizontal direction and the water injection pressure to be 6-12 MPa through a self-vibration cavitation jet device, further optimizing the shape of the cavity, and finally forming the cavity with a regular shape.

2. A control process for selective solution mining cavity construction of layered rock salt by using a single well comprises the following steps:

(1) drilling a single well from the surface, namely drilling the single well to the bottom of the salt rock, wherein a technical casing, a middle pipe and a central pipe are sequentially arranged in the single well in the dissolving production process;

(2) on the basis of identifying the thickness and the position of the interlayer, forming a hole gap in a certain range of the thick interlayer through physical action;

(3) after the thick interlayer hole seams are formed, a salt layer at the lower part of the thick interlayer is mined, the oil cushion method is utilized to control the dissolution of the dissolution cavity, the horizontal direction dissolution of the cavity is accelerated, the diameter of the dissolution cavity at the lower part is enlarged, and a space is provided for the collapse of the interlayer;

(4) lifting the central pipe and the middle pipe to the upper part of the thick interlayer, and mining the salt rock on the upper part of the thick interlayer; controlling the dissolving of the dissolving cavity by using an oil pad method; meanwhile, a self-vibration cavitation jet device is additionally arranged at the lower part of the central pipe, the underground water injection direction is adjusted to be the horizontal direction, the water injection pressure is adjusted to be 6-12 MPa, and the corrosion of the cavity in the horizontal direction is accelerated;

(5) adjusting the water outlet of the central pipe to the thick interlayer, directly eroding the thick interlayer by using a self-vibration cavitation jet device, and further promoting the erosion and the peeling of the thick interlayer, wherein a certain amount of chemical substances are optionally added into the water solution of the injection well to accelerate the erosion of interlayer substances;

(6) after the thick interlayer collapses, controlling the upward dissolution by using an oil pad, and continuously exploiting an upper salt layer; and adjusting the underground water injection direction to be the horizontal direction and the water injection pressure to be 6-12 MPa through a self-vibration cavitation jet device, further optimizing the shape of the cavity, and finally forming the cavity with a regular shape.

3. A control process for selective solution mining cavity construction of layered rock salt by utilizing double wells comprises the following steps:

(1) drilling two wells, namely a vertical well and a horizontal butt well from the ground surface, wherein the distance between the two wells is generally 50-300 m, preferably 150-210 m, and a technical casing pipe and a middle pipe are sequentially arranged in the wells in the dissolving production process of the wells;

(2) after drilling is finished, on the basis of identifying the thickness and the position of an interlayer, forming hole seams in a certain range in thick interlayers around the shafts of the two wells respectively through physical action;

(3) after the thick interlayer hole seams are formed, mining a salt layer at the lower part of the thick interlayer; diesel oil is injected into an annular gap between the technical sleeve and the middle pipe to control the dissolution of the dissolution cavity; the vertical well and the horizontal butt-joint well are periodically and alternately injected with water and discharged with brine, so that the corrosion of the cavity in the horizontal direction is accelerated, the diameter of the lower cavity is enlarged, and a space is provided for the collapse of the interlayer;

(4) lifting the middle pipe to the upper part of the thick interlayer, and mining the salt rock on the upper part of the thick interlayer; diesel oil is injected into an annular gap between the technical sleeve and the middle pipe to control the upper dissolution of the dissolution cavity; meanwhile, a self-vibration cavitation jet device is additionally arranged at the lower part of the middle pipe, the underground water injection direction is adjusted to be the horizontal direction, the water injection pressure is adjusted to be 6-12 MPa, and the corrosion of the cavity in the horizontal direction is accelerated;

(5) adjusting the water outlet of the middle pipe to the thick interlayer, directly and respectively eroding the thick interlayers of the two salt wells by using a self-vibration cavitation jet device, and further promoting the erosion and the peeling of the thick interlayers, wherein optionally, a certain amount of chemical substances for accelerating the erosion of interlayer substances are added into the water solution of the injection well;

(6) after the thick interlayer collapses, controlling the upward dissolution by using an oil pad, and continuously exploiting an upper salt layer; and adjusting the underground water injection direction to be the horizontal direction and the water injection pressure to be 6-12 MPa through a self-vibration cavitation jet device, further optimizing the shape of the cavity, and finally forming the cavity with a regular shape.

4. The method according to any one of claims 1 to 3, wherein in step (2), the thick interbedded layer refers to a poorly soluble or insoluble rock formation in the rock salt having a thickness of 3 to 30m, preferably 10 to 20 m.

5. A method according to any one of claims 1-3, wherein in step (2), the method of forming apertures in the thick interlayer by physical action essentially comprises:

(1) the single well hole fractures the thick interlayer, so that effective gaps and cracks are formed in the thick interlayer; and/or

(2) And drilling a horizontal well in the thick interlayer by sidetracking, forming a series of drilled holes in the thick interlayer, and then fracturing in a small range to form effective gaps and cracks in the thick interlayer.

6. A process according to any one of claims 1 to 3, wherein in step (4), the upper cavity height is controlled to be 5 to 30m, preferably 10 to 15 m.

7. A method according to any one of claims 1 to 3 wherein in step (5) a chemical substance for accelerating the erosion of the interlayer material is added to the aqueous injection well solution in dependence on the composition of the material of the interlayer in the salt rock, for example where glauberite is present in the interlayer, CaCl is added to the aqueous injection well solution₂。

8. The method of claim 7, wherein CaCl is added to the well injection water solution at a concentration of 20-200 g/L, preferably 100-150 g/L₂。

9. A method according to any of claims 1-3, wherein a range is a radius of 20-60 meters, preferably 30-40 meters.

Technical Field

The invention relates to a layered rock salt selective solution mining cavity-making control technology, belongs to the technical field of cavity making of salt cavern underground reservoirs (gas storage or oil storage), and particularly relates to a selective solution mining control technology for a thick interlayer containing insoluble or insoluble salt rocks.

Background

The salt cavern storage is used for storing petroleum or natural gas by utilizing a salt cavern reserved by water solution exploitation according to the characteristics of low permeability, low porosity and the like of a salt rock stratum. Salt cavern reservoirs abroad are almost built in huge salt dunes, and the salt cavern reservoirs are large in thickness of salt rocks, high in grade, few in indissolvable substances and easy to build.

Compared with the foreign reservoir building conditions, the salt deposit in China has the disadvantages of more interlayers, low grade and the like, and the construction difficulty of the salt cavern reservoir is increased. In the process of salt cavern storage construction, the thin interlayer can naturally collapse after the lower salt rock is dissolved, while the thicker interlayer is difficult to collapse, so that the cavity is irregular in shape and even deformed, and the use requirement of the salt cavern storage cannot be met. At present, a solution for the lack of a thick interlayer in salt rock is provided, and the construction of salt cavern reservoirs in China is restricted.

Disclosure of Invention

The invention provides a control process for selective solution mining and cavity construction of layered salt rock, which solves the problem of influence of a thick interlayer on the stability of a salt cavity.

The technical scheme of the invention is as follows: according to geological data, on the basis of determining the position and thickness of an interlayer and physical and chemical properties, a mine (single well or double wells) is arranged in a mining area by means of physical damage to the interlayer and changing chemical components of a well injection solution, and selective solution mining control of a layered rock salt cavern is achieved. In the drilling stage, the thick interlayer is perforated with vertical holes and horizontal holes and is locally and directionally fractured to form a hole seam. Meanwhile, in the process of mining, the upper salt layer and the lower salt layer of the thick interlayer are mined preferentially, so that the thick interlayer is suspended and soaked in brine, and soluble substances in the interlayer are dissolved to destroy the interlayer structure. In the process of exploitation, the self-vibration cavitation jet device is utilized to adjust the underground water injection direction and water injection pressure, and the erosion to the cavity in the horizontal direction is accelerated. Meanwhile, the position of a water outlet of the self-vibration cavitation jet flow is adjusted to be aligned to the thick interlayer, so that the erosion effect on the thick interlayer is strengthened, and the denudation of the thick interlayer is promoted. In addition, according to the material composition of the salt rock interlayer, a specific chemical substance is selected and added into the injection water.

According to a first embodiment of the invention, the invention provides a layered rock salt selective solution mining cavity control process, which comprises the following steps:

(1) in the drilling stage, firstly, drilling to the bottom of the rock salt;

(2) on the basis of identifying the thickness and the position of the interlayer, forming a hole seam in the thick interlayer in the salt rock within a certain range (such as the radius of 20-60 meters, preferably within the range of 30-40 meters) through a physical action;

(3) after the thick interlayer hole seams are formed, mining a salt layer at the lower part of the thick interlayer; diesel oil is injected into an annular gap between the technical sleeve and the middle pipe to form an oil cushion layer to control the upper dissolution of the dissolution cavity, the diameter of the lower dissolution cavity is enlarged, and a space is provided for the collapse of the interlayer;

(4) adjusting the position of a casing opening of the salt well, and mining a salt layer on the upper part of the thick interlayer; injecting diesel oil into the salt well, and controlling the dissolution of the dissolution cavity; a self-vibration cavitation jet device is additionally arranged at the lower part of the water injection pipe, the water pressure of an injection well is adjusted to 6-12 MPa, preferably 8-10MPa through an injection well water pump, a rotary controller and a rotary spray head are pushed, the direction of underground water flow is adjusted to be horizontal, the pressure is adjusted to 6-12 MPa, preferably 8-10MPa, and the corrosion to the cavity in the horizontal direction is accelerated;

(5) adjusting the opening of the underground water injection pipe to the thick interlayer, and directly eroding the thick interlayer by using a self-vibration cavitation jet device to further promote the erosion and the stripping of the thick interlayer; optionally adding a certain amount of chemical substances for accelerating the erosion of interlayer substances into the well injection water solution according to the substance composition of the interlayer in the salt rock;

(6) after the thick interlayer collapses, the salt well is additionally injected with diesel oil to control the upward dissolution, and the upper salt layer is continuously exploited; and (3) additionally arranging a self-vibration cavitation jet device at the lower part of the water injection pipe, adjusting the water flow direction to be horizontal, and adjusting the water pressure of the injection well to 6-12 MPa, preferably 8-10MPa through the injection well water pump. Further optimizing the shape of the cavity, and finally forming the cavity with regular shape.

Further, in the step (2) of the invention, the identification of the thickness of the interlayer is involved, and the thick interlayer refers to a difficultly soluble or insoluble rock stratum with the thickness of 3-30 m in the salt rock, and preferably 10-20 m; in the step (4), the height of the upper cavity is controlled to be 5-30 m, preferably 10-15 m.

In the step (5) of the present invention, a specific chemical substance is added to the well injection aqueous solution according to the material composition of the interlayer in the salt rock, and the addition amount of the chemical substance for accelerating the erosion of the interlayer material in the well injection aqueous solution is, for example, 20 to 200g/L, preferably 100 to 150 g/L. For example, when glauberite is present in the interlayer, CaCl may be added to the well injection aqueous solution₂But not limited to the use of CaCl₂The concentration is 20 to 200g/L, preferably 100 to 150 g/L.

The drilling system of the invention comprises an outer technical casing, an intermediate pipe inside the technical casing and a central pipe inside the intermediate pipe.

The self-vibration cavitation jet device comprises a rotary controller and a rotary nozzle (reference document: patent No. ZL 200520016953.3; Song Xian et al, research on multi-interlayer rock salt self-vibration cavitation jet cavity-making technology, petroleum machinery, 2009, 37 (12): 20-23), is additionally arranged at the lower end of a water injection pipe, and ground liquid is injected by the water injection pipe after being pressurized, flows through the self-vibration cavitation jet device, drives the rotary controller to rotate the rotary nozzle to generate self-vibration cavitation jet in the horizontal and inclined directions, and erodes and breaks the salt rock or the interlayer.

The physical effects described herein may be (1) fracturing a single wellbore against a thick interlayer, causing the thick interlayer to form effective voids, fractures; (2) and drilling a horizontal well in the thick interlayer by sidetracking, forming a series of drilled holes in the thick interlayer, and then fracturing in a small range to form effective gaps and cracks in the thick interlayer.

Factors affecting the exfoliation of thick interlayers include:

(1) the earlier drilling fractures the cracks formed in the sandwich, causing the sandwich to fail.

(2) The mid-span of the interlayer in the brine is increased, and the collapse of the interlayer is accelerated.

(3) The self-vibration cavitation jet directly has the erosion effect on the interlayer.

(4) After the upper part and the lower part of the thick interlayer form a dissolving cavity, the interlayer is completely soaked in brine, so that the dissolution of soluble substances in the interlayer is promoted, and the internal structure of the interlayer is damaged.

(5) The chemical substance in the well water solution and the substance in the interlayer are chemically reacted to form glauberite (Na) in the interlayer₂SO₄·CaSO₄) For example, glauberite is dissolved and decomposed in an aqueous solution into slightly soluble CaSO₄And soluble Na₂SO₄，Na₂SO₄Can be mixed with CaCl₂Reaction is carried out: CaCl₂+Na₂SO₄+2H₂O＝2NaCl+CaSO₄·2H₂And O ↓promotesthe interlayer erosion and accelerates the collapse of the interlayer.

The invention can select single well or double wells.

In one embodiment, the present invention provides a process for controlling selective dissolution production cavity of layered rock salt using a single well, comprising the steps of:

(1) drilling a single well from the surface, namely drilling the single well to the bottom of the salt rock, wherein a technical casing, a middle pipe and a central pipe are sequentially arranged in the single well in the dissolving production process;

(2) on the basis of identifying the thickness and the position of the interlayer, forming a hole gap in a certain range (such as the range of radius 20-60 meters, preferably 30-40 meters) of the thick interlayer through physical action;

(3) after the thick interlayer hole seams are formed, a salt layer at the lower part of the thick interlayer is mined, diesel oil is injected into an annular gap between a technical sleeve and a middle pipe, the dissolution of a dissolution cavity is controlled, the horizontal corrosion of the cavity is accelerated, the diameter of the dissolution cavity at the lower part is enlarged, and a space is provided for the collapse of the interlayer;

(4) lifting the central pipe and the middle pipe to the upper part of the thick interlayer, and mining the salt rock on the upper part of the thick interlayer; diesel oil is injected into an annular gap between the technical sleeve and the middle pipe to control the upper dissolution of the dissolution cavity; meanwhile, a self-vibration cavitation jet device is additionally arranged at the lower part of the central pipe, the water pressure of the injection well is adjusted to 6-12 MPa through an injection well water pump, a rotary controller and a rotary spray head are pushed, the water flow direction is adjusted to be horizontal, the pressure is adjusted to 6-12 MPa, and the corrosion to the cavity in the horizontal direction is accelerated;

(5) adjusting a water outlet of a central pipe to the thick interlayer, directly eroding the thick interlayer by using a self-vibration cavitation jet device, and further promoting the erosion and the peeling of the thick interlayer, wherein a certain amount of chemical substances for accelerating the erosion of interlayer substances are optionally added into the water solution of the injection well according to the substance components of the interlayer in the salt rock;

(6) after the thick interlayer collapses, controlling the upward dissolution by using an oil pad, and continuously exploiting an upper salt layer; and (3) additionally arranging a self-vibration cavitation jet device at the lower part of the water injection pipe, adjusting the water flow direction to be horizontal, and adjusting the water pressure of the injection well to 6-12 MPa, preferably 8-10MPa through the injection well water pump. Further optimizing the shape of the cavity, and finally forming the cavity with regular shape.

Wherein, in the production process of solution mining, the relative position of the central pipe and the middle pipe is mainly determined according to the shape of the cavity.

In another embodiment, the present invention relates to a process for controlling selective dissolution production cavity for layered rock salt using twin wells, comprising the steps of:

(1) drilling two wells, namely a vertical well and a horizontal butt well from the ground surface, wherein the distance between the two wells is generally 50-300 m, preferably 150-210 m, and a technical casing pipe and a middle pipe are sequentially arranged in the wells in the dissolving production process of the wells;

(2) after drilling, on the basis of identifying the thickness and position of an interlayer, forming hole seams in a certain range (such as the range of radius 20-60 meters, preferably 30-40 meters) in thick interlayers around the shafts of the two wells through physical action;

(3) after the thick interlayer hole seams are formed, mining a salt layer at the lower part of the thick interlayer; diesel oil is injected into an annular gap between the technical sleeve and the middle pipe to control the dissolution of the dissolution cavity; the vertical well and the horizontal butt-joint well are periodically and alternately injected with water and discharged with brine, so that the corrosion of the cavity in the horizontal direction is accelerated, the diameter of the lower cavity is enlarged, and a space is provided for the collapse of the interlayer;

(4) lifting the middle pipe to the upper part of the thick interlayer, and mining the salt rock on the upper part of the thick interlayer; diesel oil is injected into an annular gap between the technical sleeve and the middle pipe to control the upper dissolution of the dissolution cavity; meanwhile, a self-vibration cavitation jet device is additionally arranged at the lower part of the water injection pipe, the water pressure of the injection well is adjusted to 6-12 MPa through an injection well water pump, a rotary controller and a rotary spray head are pushed, the water flow direction is adjusted to be horizontal, the pressure is adjusted to 6-12 MPa, and the corrosion to the cavity in the horizontal direction is accelerated;

(5) adjusting the water outlet of the middle pipe to the thick interlayer, directly and respectively eroding the thick interlayers of the two salt wells by using a self-vibration cavitation jet device, and further promoting the erosion and the stripping of the thick interlayers; optionally adding a certain amount of chemical substances for accelerating the erosion of interlayer substances into the well injection water solution according to the substance composition of the interlayer in the salt rock;

(6) after the thick interlayer collapses, controlling the upward dissolution by using an oil pad, and continuously exploiting an upper salt layer; and (3) additionally arranging a self-vibration cavitation jet device at the lower part of the water injection pipe, adjusting the water flow direction to be horizontal, and adjusting the water pressure of the injection well to 6-12 MPa, preferably 8-10MPa through the injection well water pump. Further optimizing the shape of the cavity, and finally forming the cavity with regular shape.

Wherein, in the solution production process, the position of the middle pipe orifice of the two salt wells is mainly determined according to the shape of the cavity.

In the two embodiments, the chemical substance for accelerating the erosion of the interlayer substance is added into the well injection water solution at a concentration of, for example, 20-200 g/L, preferably 100-150 g/L, including but not limited to calcium chloride.

In this application, "optionally" means that the subsequent step is performed or not performed.

Further, in the present invention, a specific chemical is added to the well injection water solution according to the composition of matter of the interlayer in the salt rock. For example, interlayersThe composition contains glauberite (Na)₂SO₄·CaSO₄) In this case, CaCl may be added to the well injection aqueous solution₂The concentration is 20-200 g/L, preferably 100-150 g/L, but not limited to using CaCl₂. Glauberite is dissolved and decomposed into slightly soluble CaSO in water solution₄And soluble Na₂SO₄，Na₂SO₄Can be mixed with CaCl₂Reaction is carried out: CaCl₂+Na₂SO₄+2H₂O＝2NaCl+CaSO₄·2H₂And O ↓promotesthe interlayer erosion and accelerates the collapse of the interlayer.

In the present invention, factors that affect the exfoliation of thick interbeddes in layered rock salt include:

(1) the earlier drilling fractures the cracks formed in the sandwich, causing the sandwich to fail.

(2) The mid-span of the interlayer in the brine is increased, and the collapse of the interlayer is accelerated.

(3) The self-vibration cavitation jet directly has the erosion effect on the interlayer.

(4) After the upper part and the lower part of the thick interlayer form a dissolving cavity, the interlayer is completely soaked in brine, so that the dissolution of soluble substances in the interlayer is promoted, and the internal structure of the interlayer is damaged.

(5) Chemical substances in the well injection water solution and substances in the interlayer are subjected to chemical reaction, so that the interlayer corrosion is promoted, and the collapse of the interlayer is accelerated.

The invention has the advantages that: aiming at the problem that the thick interlayer is difficult to peel off in the cavity making process, the method comprehensively utilizes the methods of physical damage, chemical corrosion and the like, promotes the peeling and the collapse of the interlayer in the salt rock, solves the problem that the thick interlayer in the layered salt rock is difficult to collapse, and realizes the effective control of the shape of the cavity of the salt cavern storage.

Drawings

FIG. 1 is a schematic view of a single well thick interbed fracture profile of the present invention.

Fig. 2 is a schematic plan view of a thick interlayer fracture of the present invention.

FIG. 3 is a schematic view of a single well thick interbedded lower cavity construction in the practice of the present invention.

FIG. 4 is a schematic diagram of a single well for creating a cavity above a thick interbed in accordance with embodiments of the present invention.

FIG. 5 is a schematic diagram of a single well for erosion, spalling, and collapse of a thick interlayer in accordance with an embodiment of the present invention.

FIG. 6 is a schematic diagram of a single well salt cavity configuration after practice of the present invention.

FIG. 7 is a schematic representation of a dual well thick interbedded fracture profile of the present invention.

FIG. 8 is a schematic view of the cavity created below the double well thick interbed in the practice of the present invention.

FIG. 9 is a schematic diagram of dual wells for creating a cavity above a thick interbed in accordance with embodiments of the present invention.

FIG. 10 is a schematic diagram of dual wells eroding, spalling, and collapsing a thick interlayer in accordance with an embodiment of the present invention.

FIG. 11 is a schematic diagram of a twin well salt cavity configuration after practice of the invention.

In the figure: 1-rock salt overburden; 2-salt rock; 3, a thick interlayer; 4-salt rock; 5-thin interlayer; 6-salt rock; 7-rock salt underburden; 8, single well; 9-side holes; 10-cracking; 11-technical casing; 12-intermediate pipe; 13-a central tube; 14-oil cushion layer; 15-dissolving cavity; 16-bottoms; 17-self-vibration cavitation jet device; 18-vertical well; 19-horizontal docking well; 20-vertical well technical casing; 21-horizontal butt well technology casing; 22-vertical well middle pipe; 23-horizontally butting well intermediate pipes; 24-horizontally docking the well dissolution cavity; 25-vertical well karst cavity.

Detailed Description

For a further understanding of the present invention, reference will now be made in detail to the following examples, which are included to illustrate, but are not to be construed as limiting the present invention, and it is intended that the description be regarded as illustrative rather than restrictive, and that the features and advantages of the present invention are provided. Any equivalent replacement in the field made in accordance with the present disclosure is within the scope of the present invention.