Linked hydraulic fracturing ground stress testing device and testing method

Abstract

The present invention provides a linkage type hydraulic fracturing method ground stress testing device and testing method, including a pressure relief device, an upper packer and a lower packer connected to the pressure relief device in sequence, the pressure relief device including: an upper valve body connected to a drill pipe during testing, the upper valve body including a first shell and a limit device arranged in the first shell; a base elastically connected to the first shell, the base also connected to the limit device; a lower valve body including a second shell and a lower valve body piston movably arranged in the second shell, a second inner cavity and a third water outlet are arranged in the second shell, a central flow channel and a fourth water outlet connected to the central flow channel are arranged in the lower valve body piston, the second inner cavity is also connected to a central pipeline, the central pipeline connects the lower valve body, the upper packer and the lower packer, and a test section water outlet is arranged on the central pipeline. The present invention can quickly relieve pressure on the upper and lower packers by controlling the rise and fall of the drill pipe during the test.

Description

Technical Field

[0001] The invention belongs to the technical field of rock mass mechanics testing, and in particular relates to a linkage type hydraulic fracturing method ground stress testing device and a testing method. Background Art

[0002] Conventional hydraulic fracturing method for geostress testing is mainly divided into single-tube method and double-tube method. The single-tube method switches the pressure channel between the packer and the test section by connecting a push-pull valve between the drill pipe and the double-plug packer. It is suitable for continuous and rapid testing of deep boreholes with high water levels (generally the water level does not exceed 50m) and is simple to operate. The double-tube method forms two pressure channels by connecting a slender high-pressure water pipe to the packer and the drill pipe. It is suitable for shallow borehole testing and is complex to operate. As the burial depth of underground projects increases, geological boreholes with large burial depths and deep water levels will be common. The single-tube method is generally used for testing. However, the pressure formed by the head difference between the inside and outside of the drill pipe during water injection will cause the packer to expand autonomously and be fixed on the hole wall and unable to move. Therefore, a matching pressure relief device is required to relieve the pressure of the packer separately. The existing pressure relief method is relatively inefficient and the required testing time is much longer than that of high-water-level drilling.

[0003] At present, there are two main types of pressure relief methods with high operability: the first type of pressure relief method cannot be tested continuously after the pressure of the packer is removed. After a test section is completed, the packer needs to be completely lifted to the ground through the drill pipe, the pressure relief device needs to be manually restored, and then the drill pipe needs to be connected again and lifted to the designated position through the drilling rig winch and water needs to be re-injected into the drill pipe. This pressure relief method is the least efficient, and a lot of time and manpower are spent on connecting and disassembling the drill pipe during repeated lifting and the water injection stage before testing; the second type of pressure relief method is to fine-tune the stroke of the piston in the pressure relief device by accurately controlling the lifting and lowering of the drill pipe on the ground so that the water in the drill pipe flows into the borehole, reducing the head difference inside and outside the drill pipe, and achieving the purpose of packer pressure relief. After pressure relief, it can be lifted by the drilling rig winch and placed at the next test position for continuous testing, but water needs to be re-injected into the drill pipe before testing. This pressure relief method is more efficient than the first method, and does not require repeated lifting of the drill pipe, but the water release of the drill pipe during the pressure relief process and the water injection before retesting still take a long time. Although the above two methods achieve the purpose of pressure relief, their efficiency is very low, and clean water resources at the test site are often scarce. Therefore, in order to save time, manpower and material resources, improve test efficiency and reduce test costs, it is of great significance to invent a hydraulic fracturing ground stress test device and test method suitable for deep drilling and low water level, which is efficient and easy to operate. Summary of the invention

[0004] One object of the present invention is to address the deficiencies of the prior art and provide a linkage type hydraulic fracturing method geostress testing device, which can adjust the pressure relief device for water injection or pressure relief only by controlling the drill pipe, thereby achieving the purpose of rapid pressure relief of the packer, preservation of the drill pipe water head and pressure channel switching in deep drilling low water level testing.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0006] A linkage type hydraulic fracturing method in-situ stress testing device, the testing device comprising a pressure relief device, an upper packer connected to the pressure relief device through a first pipeline, and a lower packer connected to the upper packer through a second pipeline, wherein the pressure relief device comprises:

[0007] An upper valve body, which is connected to the drill pipe during testing, and includes a first shell and a limiting device. A first inner cavity extending along its axial direction and connected to the drill pipe, a first water outlet hole and a second water outlet hole connected to the first inner cavity are provided in the first shell. A first channel and a second channel are provided on the limiting device, wherein the first water outlet hole and the second water outlet hole, and the first channel and the second channel are not connected to each other. The limiting device is provided in the first inner cavity and can be selectively moved in the first inner cavity. When the limiting device is fixed in the first inner cavity, the first channel is connected to the first water outlet hole. When the limiting device moves to the limit position in the first inner cavity, the first water outlet hole, the second channel and the second water outlet hole are connected in sequence.

[0008] A base is elastically connected to the first shell, and the base is also connected to the limit device. When the base and the first shell move away from each other to the limit position, the limit device moves in the first inner cavity under the action of the base; a third channel is also provided in the base, and one end of the third channel is connected to the first water outlet through a third pipeline;

[0009] The lower valve body comprises a second shell and a lower valve body piston connected to the base, a second inner cavity and a third water outlet are arranged in the second shell, a central flow channel and a fourth water outlet connected to the central flow channel are arranged in the lower valve body piston, the lower valve body piston is movably arranged in the second inner cavity, when the lower valve body piston moves to an extreme position in the second inner cavity toward the base, the third water outlet is connected to the fourth water outlet, when the lower valve body piston moves to an extreme position in the second inner cavity toward the direction away from the base, the third water outlet is connected to the fourth water outlet. It is separated from and not connected to the fourth water outlet; the third water outlet is also connected to the upper packer through the first pipeline. In addition, the second inner cavity is also connected to the central pipe. The end of the central pipe away from the upper packer is a closed section. The central pipe passes through the upper packer and the lower packer to connect the lower valve body, the upper packer and the lower packer. A test section water outlet for injecting water into the test section is provided on the central pipe between the upper and lower packers. When the third water outlet is separated from and not connected to the fourth water outlet, the water in the central flow channel flows from the fourth water outlet to the second inner cavity and the central pipe in sequence.

[0010] Furthermore, the limiting device includes a first spring connected to the upper valve body at one end, an upper valve body piston connected to the other end of the first spring, a limiting pin arranged on the side wall of the first inner cavity and used to limit the movement of the upper valve body piston, and a connecting rope connected to the limiting pin at one end and the base at the other end, wherein the first channel and the second channel are arranged on the upper valve body piston, an L-shaped mounting hole for installing the limiting pin is arranged on the side wall of the first shell, and a corresponding slot is also arranged on the upper valve body piston. In an initial state, the limiting pin is inserted from the mounting hole into the slot to fix the upper valve body piston, and the connecting rope is pulled to pull the limiting pin out of the slot. The upper valve body piston moves in the first inner cavity under the action of the first spring, and when the limiting pin is inserted into the slot, the first spring is in a stretched state.

[0011] Furthermore, the first inner cavity includes a first cavity and a second cavity connected to the first cavity, the inner diameter of the first cavity is larger than the inner diameter of the second cavity, the upper valve body piston is T-shaped, and includes a first piston body and a second piston body vertically connected to the first piston body, wherein the first piston body is adapted in the first cavity, and the second piston body is adapted in the second cavity, when the upper valve body piston moves in the first inner cavity to the point where the first piston body is located at the connection between the first cavity and the second cavity, the slot is aligned with the mounting hole, and the limit pin is inserted from the mounting hole into the slot.

[0012] Furthermore, a plurality of sealing rings are arranged at intervals on the inner wall of the first inner cavity, and the plurality of sealing rings are respectively used to block the water flow in the first inner cavity from directly flowing into the first water outlet and to block the water flow between the first channel and the second channel.

[0013] Furthermore, a push-pull device connected to the first spring is also provided on the first shell, and the push-pull device includes a bolt with one end passing through the first shell and connected to one end of the first spring, and a nut connected to the bolt by a thread. When the nut is screwed, the bolt compresses the first spring or stretches the first spring.

[0014] Furthermore, the first shell is elastically connected to the base, and the elastic connection structure includes a connector outer sleeve arranged on the bottom surface of the first shell, a baffle movably arranged inside the connector outer sleeve, a connecting shaft with one end connected to the baffle and the other end extending out of the connector outer sleeve, and a second spring sleeved on the connecting shaft and connected to the baffle at one end and the connector outer sleeve at the other end. When the connecting shaft is pulled in the direction of the lower valve body, the second spring is compressed. In addition, the other end of the connecting shaft is connected to the base.

[0015] Furthermore, the lower valve body piston and the second inner cavity cooperate to set a limiting structure, and the limiting structure is specifically:

[0016] The second inner cavity includes a third cavity and a fourth cavity connected to the third cavity, wherein the inner diameter of the third cavity is smaller than the inner diameter of the fourth cavity, and the lower valve body piston includes an integrally formed third piston body and a fourth piston body, the outer diameter of the third piston body is equivalent to the inner diameter of the third cavity, the outer diameter of the fourth piston body is equivalent to the inner diameter of the fourth cavity, and the length of the fourth cavity is greater than the length of the fourth piston body, the fourth piston body is adapted in the fourth cavity and when the fourth piston body moves to the connection between the fourth cavity and the third cavity, the lower valve body piston can no longer move upward and is limited, and at this time, the central flow channel, the fourth water outlet and the third water outlet are connected in sequence.

[0017] Furthermore, a limit plate is provided on the fourth piston body, and the limit plate is used to limit the maximum descending distance of the fourth piston body in the fourth cavity.

[0018] Furthermore, a plurality of sealing rings are arranged at intervals on the inner wall of the second inner cavity, and the plurality of sealing rings are used to prevent the water flow in the fourth water outlet from flowing through the second cavity to the third water outlet.

[0019] Another object of the present invention is to provide a testing method according to the above-mentioned linkage type hydraulic fracturing method ground stress testing device, comprising the following steps:

[0020] Step 1, connect the pressure relief device, the upper packer and the lower packer of the test device in sequence, and then connect the pressure relief device to the drill pipe. In the initial state, the pressure relief device is in a stretched state, the limit device is fixed in the first inner cavity, the first channel is connected to the first water outlet, the lower valve body piston is located at the limit position away from the base in the second inner cavity, and the third water outlet is separated from the fourth water outlet; then lower the test device to a selected position in the borehole through the drill pipe. During the lowering process, under the action of gravity, the lower valve body piston moves to the limit position relative to the second shell in the second inner cavity toward the base. At this time, the third water outlet is connected to the fourth water outlet, and the high-pressure water flows from the drill pipe to the first inner cavity, the first channel, the first water outlet, the third pipeline, the third channel, the central flow channel, the fourth water outlet, the third water outlet, the first pipeline, the upper packer, the second pipeline, and the lower packer in sequence. The upper packer and the lower packer expand and cling to the borehole under the action of the high-pressure water flow, forming a test section between the upper and lower packers;

[0021] Step 2, press down the drill pipe, when the piston of the lower valve body moves to the extreme position in the second inner cavity in the direction away from the base, the third water outlet is separated from the fourth water outlet and is not connected, and the high-pressure water flow in the drill pipe flows through the first inner cavity, the first channel, the first water outlet, the third pipeline, the third channel, the central flow channel, the fourth water outlet to the second inner cavity below the fourth water outlet, and then flows from the second inner cavity to the central pipeline and through the test section outlet on the central pipeline to pressurize the selected test section and perform water injection and test;

[0022] Step 3, after the ground stress test of step 2 is completed, the drill pipe is lifted upward. Since the upper and lower packers are sealed, when the piston of the lower valve body moves to the limit position in the direction of the base in the second inner cavity, the third water outlet is connected with the fourth water outlet, and the lifting is continued until the base and the first shell move away from each other to the limit position. Under the action of the base, the limit device moves to the limit position in the first inner cavity. At this time, the second channel is connected with the first water outlet, and the water in the lower packer and the upper packer passes through the second pipeline, the first pipeline, the third water outlet, the fourth water outlet, the central flow channel, the third channel, the third pipeline, the first water outlet, and the second channel in sequence, thereby flowing into the first inner cavity and finally flowing out from the second water outlet, thereby releasing the pressure in the upper and lower packers;

[0023] The fourth step is to completely release the pressure in the upper and lower packers, restore the base and the first shell to their initial state under the action of elastic force, and then move the drill pipe to the next selected test position. Before the test, apply pressure to the first inner cavity through the drill pipe, and restore the limit device to its initial state under the action of pressure, and repeat the above steps to test the next test section.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) The present invention does not need to consider the water head difference between the inside and outside of the drill pipe during the test process. The water path in the pressure relief device can be switched only by controlling the rise and fall of the drill pipe, thereby achieving the purpose of quickly relieving the pressure of the upper and lower packers;

[0026] (2) The present invention does not require repeated lifting of the drill pipe. The upper valve body can be restored to its initial state by simply applying pressure inside the drill pipe, which greatly saves testing time and reduces the risk of repeated drilling up and down.

[0027] (3) Due to the structural characteristics of the upper valve body, the present invention can preserve the water in the drill pipe when the pressure is released, thus saving the time required for draining and injecting water into the drill pipe;

[0028] (4) The present invention fully utilizes the internal pressure of the drill pipe to return the piston in the valve body, has a simple and practical structure, can improve the test efficiency, and reduce the test cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a structural schematic diagram of the initial state of the linkage type hydraulic fracturing method ground stress testing device according to an embodiment of the present invention;

[0030] Figure 2 It is a schematic structural diagram of the upper and lower packers of the linked hydraulic fracturing method ground stress testing device according to the embodiment of the present invention when water is injected to seal the upper and lower packers;

[0031] Figure 3 This is a schematic structural diagram of the linked hydraulic fracturing method in-situ stress testing device for water injection into a test section according to an embodiment of the present invention;

[0032] Figure 4 It is a schematic structural diagram of the linkage type hydraulic fracturing ground stress testing device according to an embodiment of the present invention when it is pulled up and depressurized. DETAILED DESCRIPTION

[0033] The technical solutions in the embodiments of the present invention will be described clearly and completely below in combination with 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.

[0034] It should be noted that the experimental methods described in the following embodiments are conventional methods unless otherwise specified, and the reagents and materials are commercially available unless otherwise specified; in the description of the present invention, the terms "lateral", "longitudinal", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0035] The present invention will be further described below in conjunction with specific embodiments, but the present invention is not limited thereto.

[0036] like Figure 1As shown, an embodiment of the present invention discloses a linkage type hydraulic fracturing method ground stress testing device, including a pressure relief device, an upper packer 5 connected to the pressure relief device through a first pipeline 4, and a lower packer 7 connected to the upper packer 5 through a second pipeline 6. Among them, the pressure relief device includes an upper valve body, a base 2 and a lower valve body connected in sequence. During the test, the upper valve body is connected to the drill pipe. In this embodiment, the upper valve body includes a first shell 100 and a limit device arranged in the first shell 100. Specifically, a first inner cavity extending along its axial direction, a first water outlet 101 and a second water outlet 102 connected to the first inner cavity are arranged in the first shell 100, and a through hole connected to the first inner cavity is also arranged at the top of the first shell 100, so that when the drill pipe is connected to the upper valve body, the drill pipe is connected to the first inner cavity through the through hole. The first water outlet 101 is an L-shaped water outlet, which is arranged on the side wall of the first inner cavity, and the second water outlet 102 is arranged at the bottom of the side wall of the first inner cavity. The limiting device includes a first spring 103 connected to the first housing 100 at one end, an upper valve body piston connected to the other end of the first spring 103, a limiting pin 104 arranged on the side wall of the first inner cavity and used to limit the movement of the upper valve body piston, and a connecting rope 105 connected to the limiting pin 104 at one end and the base 2 at the other end. In order to facilitate the return of the limiting pin, the first inner cavity includes a first cavity 106 and a second cavity 107 connected to the first cavity 106, the inner diameter of the first cavity 106 is larger than the inner diameter of the second cavity 107, and the upper valve body piston is T-shaped, which includes a first piston body 108 and a second piston body 109 vertically connected to the first piston body 108, wherein the first piston body 108 is adapted in the first cavity 106, and the second piston body 109 is adapted in the second cavity 107, and when the upper valve body piston moves in the first inner cavity to the point where the first piston body is located at the connection between the first cavity 106 and the second cavity 107, the upper valve body piston cannot continue to move. An L-shaped first channel 110 and a second channel 111 are provided on the upper valve body piston. The first channel 110 and the second channel 111 are not connected to each other, the water inlet end of the first channel 110 is connected to the first cavity 106, and the water outlet end of the first channel 110 is selectively connected to the first water outlet hole 101. One end of the second channel 111 is also selectively connected to the first water outlet hole 101, and the other end of the second channel 111 is connected to the second cavity 107, and the water inlet end of the second water outlet hole 102 is also connected to the second cavity 107.In order to limit the upper valve body piston, an L-shaped mounting hole 112 for mounting a limiting pin 104 is provided on the side wall of the first shell 100, and correspondingly, a slot 113 is provided on the upper valve body piston. In the initial state, that is, when the first piston body 108 is located at the connection between the first cavity 106 and the second cavity 107, the mounting hole 112 is aligned with the slot 113, and the limiting pin 104 is inserted from the mounting hole 112 into the slot 113 to fix the upper valve body piston. At this time, the first spring 103 is in a stretched state; the connecting rope 105 is pulled, and the limiting pin 104 is pulled out of the slot 113. At this time, under the action of the elastic restoring force of the first spring 103, the upper valve body piston moves upward in the first inner cavity until the first spring 103 is in a naturally extended state. In order to facilitate the return of the limit pin 104 in the initial state, a push-pull device connected to the first spring 103 is also provided on the first shell 100, and the push-pull device includes a bolt 114 with one end passing through the top of the first shell 100 and connected to the first spring 103, and a nut 115 connected to the bolt 114 by a thread. When the nut 115 is screwed, the bolt 114 compresses or stretches the first spring 103, and then the position of the slot 113 on the upper valve body piston is regulated by the first spring 103. When the limit pin 104 is stuck in the slot 113, the upper valve body piston is limited, and the first channel 110 is connected to the first water outlet 101; when the pull rope 105 is pulled, the limit pin 104 is pulled out, and the upper valve body piston moves in the direction of the bolt under the action of the first spring 103, driving the upper valve body piston to move upward, thereby connecting the first water outlet 101 and the second channel 111, and then the first water outlet 101, the second channel 111, the second cavity 107 and the second water outlet 102 are connected in sequence. In order to prevent the water flow in the first cavity 106 from directly flowing into the first water outlet 101 and to block the water flow between the first channel 110 and the second channel 111, a sealing ring 116 is arranged on the inner wall of the first cavity where the first cavity 106 contacts the first piston body 108, on the inner wall of the second cavity where the first cavity is connected, and on the inner wall of the second cavity above and below the first water outlet 101.

[0037] The base 2 is elastically connected to the first housing 100, and the elastic connection structure includes a connector outer sleeve 200 arranged on the bottom surface of the first housing 100, a baffle 201 movably arranged inside the connector outer sleeve 200, a connecting shaft 202 with one end vertically connected to the baffle 201 and the other end extending out of the connector outer sleeve 200, and a second spring 203 sleeved on the connecting shaft 202 and connected to the baffle 201 at one end and the connector outer sleeve 200 at the other end. When the connecting shaft 202 is pulled toward the lower valve body 3, the second spring 203 is compressed. In addition, the other end of the connecting shaft 202 extending out of the connector outer sleeve 200 is connected to the base 2. A third channel 204 is arranged in the base 2, and one end of the third channel 204 is connected to the first water outlet 102 through a third pipeline 205. A connecting rope seat 206 is also provided on the base 2 , one end of the connecting rope 105 is fixed on the limiting pin 104 , and the other end of the connecting rope 105 passes through the mounting hole 112 and is fixed on the connecting rope seat 206 .

[0038] The lower valve body 3 includes a second shell 300 and a lower valve body piston connected to the base 2. A second inner cavity and a third water outlet 301 are provided in the second shell 200, a central flow channel 302 and a fourth water outlet 304 connected to the central flow channel 302 are provided in the lower valve body piston, and the lower valve body piston is movably provided in the second inner cavity. When the lower valve body piston moves to an extreme position in the second inner cavity toward the base 2, the third water outlet 301 is connected to the fourth water outlet 304. When the lower valve body piston moves to an extreme position in the second inner cavity toward a direction away from the base 2, the third water outlet 301 is separated from the fourth water outlet 304 and is not connected. In order to limit the maximum rising distance of the lower valve body piston in the second inner cavity, the lower valve body piston and the second inner cavity are provided with a limit structure, and the limit structure is specifically as follows: the second inner cavity includes a third cavity 305 and a fourth cavity 306 connected to the third cavity 305, wherein the inner diameter of the third cavity 305 is smaller than the inner diameter of the fourth cavity 306; correspondingly, the lower valve body piston includes an integrally formed third piston body 307 and a fourth piston body 308, and the outer diameter of the third piston body 307 is equivalent to the inner diameter of the third cavity 305. , the outer diameter of the fourth piston body 308 is equal to the inner diameter of the fourth cavity 306, and the length of the fourth cavity 306 is greater than the length of the fourth piston body 308. The fourth piston body 308 is adapted in the fourth cavity 306 and when the fourth piston body 308 moves to the top of the fourth cavity 306, since the inner diameter of the third cavity 305 is smaller than the outer diameter of the fourth piston body 308, the lower valve body piston cannot move upward and is limited. At this time, the central flow channel 302, the fourth water outlet 304 and the third water outlet 301 are connected in sequence. In order to limit the maximum descending distance of the lower valve body piston, a limiting plate 303 is provided on the third piston body 307. When the lower valve body piston descends to the limiting plate 303 thereon and presses against the top of the second housing 300, the lower valve body piston descends to the limit position in the second inner cavity. At this time, the third water outlet 301 and the fourth water outlet 304 are separated and not connected to each other. Two sealing rings 309 are sleeved on the inner wall of the fourth cavity 306 at intervals. The two sealing rings 309 are respectively arranged on the upper and lower sides of the third water outlet. The sealing rings are used to block the water flow in the fourth water outlet 304 from directly flowing through the fourth cavity 306 to the third water outlet 301.

[0039] The third water outlet 301 is also connected to the upper packer 5 through the first pipeline 4, and the upper packer 5 is connected to the lower packer 7 through the second pipeline 6. In addition, the lower valve body is also connected to the upper packer 5 and the lower packer 7 through the central pipeline 8, wherein the fourth cavity 306 is connected to the central pipeline 8, and the central pipeline 8 passes through the upper packer 5 and the lower packer 7 to connect the lower valve body, the upper packer and the lower packer, and the end of the central pipeline 8 away from the upper packer 5 is a closed section. A test section water outlet 800 for injecting water into the test section is provided on the central pipeline 8 between the upper and lower packers. When the third water outlet 301 is separated from the fourth water outlet 304 and is not connected, the water flow in the central flow channel 302 flows from the fourth water outlet 304 to the fourth cavity 306 and the central pipeline 8 in sequence to pressurize and inject water into the test section.

[0040] The embodiment of the present invention further provides a method for testing a linkage type hydraulic fracturing ground stress testing device, comprising the following steps:

[0041] Step 1: Connect the pressure relief device, upper packer 5, and lower packer 7 of the test device in sequence, and then connect the pressure relief device to the drill pipe. Figure 1 As shown, the first spring 103 in the pressure relief device is in a stretched state, that is, the limit pin 104 is inserted in the card slot 113, the first channel 110 on the upper valve body piston is connected with the first water outlet 101, and the lower valve body piston is lowered to the limit position in the second inner cavity (that is, the limit plate 303 is in contact with the second shell 300). At this time, the third water outlet 301 is separated from the fourth water outlet 304; then the test device is lowered to the selected position in the borehole through the drill rod. During the lowering process, Figure 2 As shown, under the action of gravity, the second housing 300 descends, and the piston of the lower valve body moves to the extreme position in the second inner cavity toward the direction of the base 2 (that is, the fourth piston body 308 moves to the top of the fourth cavity 306). At this time, the third water outlet 301 is connected with the fourth water outlet 304, and high-pressure water flow is injected into the drill pipe. The high-pressure water flow flows from the drill pipe to the first cavity 106, the first channel 110, the first water outlet 101, the third pipeline 205, the third channel 204, the central flow channel 302, the fourth water outlet 304, the third water outlet 301, the first pipeline 4, the upper packer 5, the second pipeline 6, and the lower packer 7. The upper packer 5 and the lower packer 7 expand under the action of the high-pressure water flow and are close to the borehole, forming a test section between the upper and lower packers;

[0042] Step 2: Figure 3As shown, the drill pipe is pressed down, and the piston of the lower valve body moves to the extreme position in the second inner cavity in the direction away from the base 2. At this time, the third water outlet 301 is separated from the fourth water outlet 304 and is not connected. The high-pressure water flow in the drill pipe passes through the first cavity 106, the first channel 110, the first water outlet 101, the third pipeline 205, the third channel 204, the central flow channel 302, and the fourth water outlet 304 to flow into the fourth cavity 306 below the fourth water outlet 304, and then flows from the fourth cavity 306 to the central pipe 8 and through the test section water outlet 800 on the central pipe 8 to pressurize the selected test section and perform the test;

[0043] Step 3: After the ground stress test in step 2 is completed, Figure 4 As shown, the drill pipe is lifted upward, and the piston of the lower valve body gradually rises to the limit position in the second inner cavity toward the base during the lifting process. At this time, the third water outlet 301 is connected with the fourth water outlet 304, and the drill pipe is continued to be lifted. Since the upper and lower packers are blocked in the borehole, the upper valve body continues to move upward with the drill pipe, and the connecting shaft 202 gradually compresses the second spring 203 to the shortest through the baffle 201. When the second spring 203 can no longer be compressed and the upper valve body is continuously lifted upward, the connecting rope 105 is pulled out by the tension to pull out the limit pin 104 stuck in the slot 113, and the upper valve body piston is in the first spring 103. Under the action of, the first spring 103 moves upward in the first inner cavity until the first spring 103 is in a naturally extended state. At this time, the second channel 111 is connected with the first water outlet 101, and the water flow sealed in the lower packer 5 and the upper packer 7 flows through the second pipeline 6, the first pipeline 4, the third water outlet 301, the fourth water outlet 304, the central flow channel 302, the third channel 204, the third pipeline 205, the first water outlet 101, and the second channel 111 to the second cavity 107 below the piston of the upper valve body, and finally flows out of the second water outlet 102 through the second cavity 107, thereby unloading the pressure and water flow in the upper and lower packers;

[0044] In the fourth step, after the pressure and water flow in the upper and lower packers are completely released, the base 2 and the first shell 100 are restored to the initial state under the action of the second spring 203, and then the test device is moved to the next selected test position through the drill pipe. Before the test, pressure is applied to the first inner cavity through the drill pipe, and the upper valve body piston in the first inner cavity is pressed downward and moves to the first piston body 108 at the connection between the first cavity 106 and the second cavity 107. At this time, the slot 113 is aligned with the mounting hole 112, and the drill pipe can be shaken in the direction of the slot 113 to make the limit pin 104 stuck in the slot 113, thereby restoring the piston in the upper valve body to the initial state, and repeating the above steps can complete the test of the next test section.

[0045] The above are only preferred embodiments of the present invention, and are not intended to limit the implementation methods and protection scope of the present invention. Those skilled in the art should be aware that all solutions obtained by equivalent substitutions and obvious changes made using the contents of the specification of the present invention should be included in the protection scope of the present invention.

Claims

1. A linkage type hydraulic fracturing method ground stress testing device, characterized in that: The testing device comprises a pressure relief device, an upper packer connected to the pressure relief device through a first pipeline, and a lower packer connected to the upper packer through a second pipeline, wherein the pressure relief device comprises: An upper valve body, which is connected to the drill pipe during testing, and includes a first shell and a limiting device. A first inner cavity extending along its axial direction and connected to the drill pipe, a first water outlet hole and a second water outlet hole connected to the first inner cavity are provided in the first shell. A first channel and a second channel are provided on the limiting device, wherein the first water outlet hole and the second water outlet hole, and the first channel and the second channel are not connected to each other. The limiting device is provided in the first inner cavity and can be selectively moved in the first inner cavity. When the limiting device is fixed in the first inner cavity, the first channel is connected to the first water outlet hole. When the limiting device moves to the limit position in the first inner cavity, the first water outlet hole, the second channel and the second water outlet hole are connected in sequence. A base is elastically connected to the first shell, and the base is also connected to the limit device. When the base and the first shell move away from each other to the limit position, the limit device moves in the first inner cavity under the action of the base; a third channel is also provided in the base, and one end of the third channel is connected to the first water outlet through a third pipeline; The lower valve body comprises a second shell and a lower valve body piston connected to the base, a second inner cavity and a third water outlet are arranged in the second shell, a central flow channel and a fourth water outlet connected to the central flow channel are arranged in the lower valve body piston, the lower valve body piston is movably arranged in the second inner cavity, when the lower valve body piston moves to an extreme position in the second inner cavity toward the base, the third water outlet is connected to the fourth water outlet, when the lower valve body piston moves to an extreme position in the second inner cavity toward the direction away from the base, the third water outlet is connected to the fourth water outlet. It is separated from and not connected to the fourth water outlet; the third water outlet is also connected to the upper packer through the first pipeline. In addition, the second inner cavity is also connected to the central pipe. The end of the central pipe away from the upper packer is a closed section. The central pipe passes through the upper packer and the lower packer to connect the lower valve body, the upper packer and the lower packer. A test section water outlet for injecting water into the test section is provided on the central pipe between the upper and lower packers. When the third water outlet is separated from and not connected to the fourth water outlet, the water in the central flow channel flows from the fourth water outlet to the second inner cavity and the central pipe in sequence.

2. The linkage type hydraulic fracturing method ground stress testing device according to claim 1 is characterized in that: The limiting device includes a first spring connected to the upper valve body at one end, an upper valve body piston connected to the other end of the first spring, a limiting pin arranged on the side wall of the first inner cavity and used to limit the movement of the upper valve body piston, and a connecting rope connected to the limiting pin at one end and the base at the other end, wherein the first channel and the second channel are arranged on the upper valve body piston, an L-shaped mounting hole for installing the limiting pin is arranged on the side wall of the first shell, and a corresponding card slot is also arranged on the upper valve body piston. In the initial state, the limiting pin is inserted from the mounting hole into the card slot to fix the upper valve body piston, and the connecting rope is pulled to pull the limiting pin out of the card slot. The upper valve body piston moves in the first inner cavity under the action of the first spring, and when the limiting pin is inserted into the card slot, the first spring is in a stretched state.

3. The linkage type hydraulic fracturing method ground stress testing device according to claim 2 is characterized in that: The first inner cavity includes a first cavity and a second cavity connected to the first cavity, the inner diameter of the first cavity is larger than the inner diameter of the second cavity, the upper valve body piston is T-shaped, and includes a first piston body and a second piston body vertically connected to the first piston body, wherein the first piston body is adapted in the first cavity, and the second piston body is adapted in the second cavity, when the upper valve body piston moves in the first inner cavity to the point where the first piston body is located at the connection between the first cavity and the second cavity, the slot is aligned with the mounting hole, and the limit pin is inserted from the mounting hole into the slot.

4. The linkage type hydraulic fracturing method ground stress testing device according to claim 2, characterized in that: A plurality of sealing rings are arranged at intervals on the inner wall of the first inner cavity, and the plurality of sealing rings are respectively used to block the water flow in the first inner cavity from directly flowing into the first water outlet hole and to block the water flow between the first channel and the second channel.

5. The linkage type hydraulic fracturing method ground stress testing device according to claim 2, characterized in that: A push-pull device connected to the first spring is also provided on the first shell, and the push-pull device includes a bolt with one end passing through the first shell and connected to one end of the first spring, and a nut connected to the bolt by a thread. When the nut is screwed, the bolt compresses the first spring or stretches the first spring.

6. The linkage type hydraulic fracturing method ground stress testing device according to claim 1, characterized in that: The first shell is elastically connected to the base, and the elastic connection structure includes a connector outer sleeve arranged on the bottom surface of the first shell, a baffle movably arranged inside the connector outer sleeve, a connecting shaft connected to the baffle at one end and extending out of the connector outer sleeve at the other end, and a second spring sleeved on the connecting shaft and connected to the baffle at one end and the connector outer sleeve at the other end. When the connecting shaft is pulled in the direction of the lower valve body, the second spring is compressed. In addition, the other end of the connecting shaft is connected to the base.

7. The linkage type hydraulic fracturing method ground stress testing device according to claim 1, characterized in that: The lower valve body piston and the second inner cavity cooperate to set a limit structure, and the limit structure is specifically: The second inner cavity includes a third cavity and a fourth cavity connected to the third cavity, wherein the inner diameter of the third cavity is smaller than the inner diameter of the fourth cavity, and the lower valve body piston includes an integrally formed third piston body and a fourth piston body, the outer diameter of the third piston body is equivalent to the inner diameter of the third cavity, the outer diameter of the fourth piston body is equivalent to the inner diameter of the fourth cavity, and the length of the fourth cavity is greater than the length of the fourth piston body, the fourth piston body is adapted in the fourth cavity and when the fourth piston body moves to the connection between the fourth cavity and the third cavity, the lower valve body piston can no longer move upward and is limited, and at this time, the central flow channel, the fourth water outlet and the third water outlet are connected in sequence.

8. The linkage type hydraulic fracturing method ground stress testing device according to claim 7, characterized in that: A limit plate is also provided on the fourth piston body, and the limit plate is used to limit the maximum descending distance of the fourth piston body in the fourth cavity.

9. The linkage type hydraulic fracturing method ground stress testing device according to claim 7, characterized in that: A plurality of sealing rings are arranged at intervals on the inner wall of the second inner cavity, and the plurality of sealing rings are used to prevent the water flow in the fourth water outlet from flowing through the second cavity to the third water outlet.

10. A testing method for the linkage type hydraulic fracturing ground stress testing device according to any one of claims 1 to 9, characterized in that: The steps include: Step 1, connect the pressure relief device, the upper packer and the lower packer of the test device in sequence, and then connect the pressure relief device to the drill pipe. In the initial state, the pressure relief device is in a stretched state, the limit device is fixed in the first inner cavity, the first channel is connected to the first water outlet, the lower valve body piston is located at the limit position away from the base in the second inner cavity, and the third water outlet is separated from the fourth water outlet; then lower the test device to a selected position in the borehole through the drill pipe. During the lowering process, under the action of gravity, the lower valve body piston moves to the limit position relative to the second shell in the second inner cavity toward the base. At this time, the third water outlet is connected to the fourth water outlet, and the high-pressure water flows from the drill pipe to the first inner cavity, the first channel, the first water outlet, the third pipeline, the third channel, the central flow channel, the fourth water outlet, the third water outlet, the first pipeline, the upper packer, the second pipeline, and the lower packer in sequence. The upper packer and the lower packer expand and cling to the borehole under the action of the high-pressure water flow, forming a test section between the upper and lower packers; Step 2, press down the drill pipe, when the piston of the lower valve body moves to the extreme position in the second inner cavity in the direction away from the base, the third water outlet is separated from the fourth water outlet and is not connected, and the high-pressure water flow in the drill pipe flows through the first inner cavity, the first channel, the first water outlet, the third pipeline, the third channel, the central flow channel, the fourth water outlet to the second inner cavity below the fourth water outlet, and then flows from the second inner cavity to the central pipeline and through the test section outlet on the central pipeline to pressurize the selected test section and perform water injection and test; Step 3, after the ground stress test of step 2 is completed, the drill pipe is lifted upward. Since the upper and lower packers are sealed, when the piston of the lower valve body moves to the limit position in the direction of the base in the second inner cavity, the third water outlet is connected with the fourth water outlet, and the lifting is continued until the base and the first shell move away from each other to the limit position. Under the action of the base, the limit device moves to the limit position in the first inner cavity. At this time, the second channel is connected with the first water outlet, and the water in the lower packer and the upper packer passes through the second pipeline, the first pipeline, the third water outlet, the fourth water outlet, the central flow channel, the third channel, the third pipeline, the first water outlet, and the second channel in sequence, thereby flowing into the first inner cavity and finally flowing out from the second water outlet, thereby releasing the pressure in the upper and lower packers; The fourth step is to completely release the pressure in the upper and lower packers, restore the base and the first shell to their initial state under the action of elastic force, and then move the drill pipe to the next selected test position. Before the test, apply pressure to the first inner cavity through the drill pipe, and restore the limit device to its initial state under the action of pressure, and repeat the above steps to test the next test section.

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