A device for real-time observation of rock mass cracks in hydraulic fracturing ground stress test

Abstract

The present invention discloses a device for real-time observation of rock cracks in a hydraulic fracturing method in-situ stress test, comprising: a slider, a guide rod, a camera, a camera mounting seat and a reel, wherein the guide rod is arranged between an upper and a lower packer, the slider is arranged on the guide rod and can slide along the guide rod, the edge of the slider is provided with teeth, the camera mounting seat is C-shaped and is installed on the edge of the slider, a driving gear meshing with the teeth of the slider is also arranged in the camera mounting seat, a transparent protective cover is arranged at the bottom of the camera mounting seat, a camera is arranged in the transparent protective cover, and a compass for positioning is arranged at the bottom of the transparent protective cover. The present invention can perform real-time observation of cracks in a hydraulic fracturing method in-situ stress test, can realize simultaneous testing and crack observation, does not need to open the crack again, not only improves the accuracy of crack positioning, but also simplifies the process of crack direction observation, and improves the working efficiency of the test.

Description

Technical Field

[0001] The invention relates to the technical field of hydraulic fracturing ground stress testing, and in particular to a device for real-time observation of rock mass cracks in hydraulic fracturing ground stress testing. Background Art

[0002] The principle of hydraulic fracturing geostress test is to use a pair of expandable rubber packers to isolate a section of the borehole at a predetermined test depth, and then pump in liquid medium to apply pressure to the isolation section. According to the characteristic values ​​of the fracturing process curve, pressure parameters such as the bursting pressure, instantaneous closing pressure, and reopening pressure can be obtained, and the planar geostress state can be directly deduced from the direction of the fracture.

[0003] There are currently two methods for observing the direction of cracks. The first method is to place a mold to the test depth after the test, apply a certain pressure to the mold to expand it, open the closed cracks in the rock again, and leave marks on the surface of the mold. Then take it out, find the crack indentation on the surface of the mold, and determine the crack direction through the compass fixed to the mold. The second method is to place the drilling camera equipment to the test depth after the test, find the position of the crack on the rock wall by visual inspection, and determine the direction through the compass.

[0004] Both methods have obvious defects. In the first method, the surface of the impression device is flexible rubber, which is easy to leave marks. The wall of the drilled hole is not completely smooth. In actual use, the surface of the impression device will be covered with various marks after it is taken out of the drilled hole, making it difficult to distinguish the cracks and indentations of the rock mass. In the second method, since the hydraulic fracturing equipment is usually lowered to the test section with a drill rod, and the drilling camera equipment is lowered to the test section with a data line, when the hole is drilled deeper, it will produce a large error and often deviate from the test section. In addition, the cracks in the rock mass are relatively small. After closing, it is difficult to detect with the naked eye, so this method also has great limitations. Summary of the invention

[0005] In order to overcome the problems existing in the prior art and facilitate real-time observation of rock cracks during the test, the present invention provides a device for real-time observation of rock cracks in a hydraulic fracturing ground stress test, and the specific technical solution is as follows.

[0006] A device for real-time observation of rock cracks in a hydraulic fracturing ground stress test, comprising: an upper packer, a lower packer, and a flower tube and a packer connecting pipe connected between the upper packer and the lower packer, characterized in that it also comprises: a slider, a guide rod, a camera and a camera mounting seat, the guide rod is arranged between the upper packer and the lower packer and is parallel to the flower tube, the slider is arranged on the guide rod and can slide along the guide rod, the edges of the upper surface and the lower surface of the slider are both provided with a slide groove, the slide groove is an arc or a circle surrounding the flower tube, The edge of the slider is provided with teeth, the camera mounting seat is C-shaped and is installed on the edge of the slider, the camera mounting seat is provided with a roller located in a slide groove on the upper surface of the slider and a roller located in a slide groove on the lower surface of the slider, the camera mounting seat is also provided with a driving gear meshing with the teeth of the slider, the camera mounting seat is also provided with a driving motor for driving the driving gear, a transparent protective cover is provided at the bottom of the camera mounting seat, a camera is provided in the transparent protective cover, and a compass for positioning is provided at the bottom of the transparent protective cover.

[0007] When in use, the upper and lower packers are sealed at the upper and lower ends of the test borehole section, and water is injected into the upper and lower packers to form a closed rock section. The test is started, and water is injected into the test borehole section through the flower tube to form pressure on the test section rock. When the water pressure is monitored to decrease, that is, a small crack is generated in the test section rock, and the water flows into the rock from the crack. At this time, the slider is controlled to move along the guide rod on the ground, and the camera mounting seat is controlled to move along the slide groove of the slider, so that the camera can move along the axial direction of the borehole and around the flower tube (along the circumferential / annular movement of the borehole), which is convenient for all-round real-time observation of the borehole wall of the test section. The camera has its own lighting device, which can accurately observe the position of the crack in real time. Combined with the compass, the orientation of the crack can be determined, and the orientation of the minimum plane principal stress of the rock mass can be tracked and determined. The camera preferably uses a wide-angle camera or a panoramic camera, which can display the borehole wall and the compass at the same time in one observation field; the compass is a conventional compass in the hydraulic fracturing method ground stress test.

[0008] Furthermore, the electric wires of the driving motor and the data wires of the camera are led out from the camera mounting seat and then wound on a wire reel, the wire reel is arranged at the bottom of the upper packer, and the electric wires and the data wires are led to the controller on the surface through the wire reel and the upper packer. The wire reel has a coil spring, so that the electric wires and the data wires can automatically follow the movement of the camera mounting seat.

[0009] Furthermore, a guide rail parallel to the guide rod is connected between the upper packer and the lower packer, the guide rail passes through the guide rail hole of the slider, the guide rail is a rack, a slider gear meshing with the guide rail is arranged in the slider, a slider motor for driving the slider gear is also arranged in the slider, the slider motor is controlled by a remote control module, the remote control module is arranged at the bottom of the upper packer, and the control line of the remote control module is led to the controller on the surface through the upper packer. The staff on the surface controls the forward or reverse rotation of the slider motor through the remote control module to adjust the rise or fall of the slider. Of course, those skilled in the art can also use other means to move the slider, such as: fixing the slider on a transmission belt.

[0010] Furthermore, the center of the slider has a hollow structure for the flower tube to pass through; this facilitates controlling the camera mounting seat to move around the flower tube to achieve a maximum observation field of view.

[0011] The present invention can observe cracks in a hydraulic fracturing ground stress test in real time, and can realize simultaneous testing and crack observation without opening the crack again, which not only improves the accuracy of crack positioning, but also simplifies the process of crack direction observation and improves the working efficiency of the test. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is an overall schematic diagram of the present invention;

[0013] Figure 2 is a schematic diagram of a slider of the present invention;

[0014] Figure 3 is a schematic diagram of a camera mounting base of the present invention;

[0015] Figure 4 It is a schematic diagram of a guide rail of the present invention.

[0016] In the figure: 1-middle through conduit, 2-upper packer, 3-packer wire groove, 4-remote control module, 5-reel, 6-camera mounting seat, 7-camera, 8-transparent protective cover, 9-compass, 10-guide rod, 11-flower tube, 12-guide rail, 13-packer connecting pipe, 14-closed iron pipe, 15-lower packer, 16-slider, 17-guide rod hole, 18-guide rail hole, 19-slider motor, 20-slider gear, 21-slide groove, 22-roller, 23-drive motor, 24-drive gear, 25-mounting seat wire groove, 26-notch, 27-tooth. DETAILED DESCRIPTION

[0017] The present invention is further described in detail below in conjunction with the accompanying drawings.

[0018] See also Figure 1-4A device for real-time observation of rock cracks in a hydraulic fracturing ground stress test, comprising an upper packer 2 and a lower packer 15, wherein the upper packer 2 has a central through conduit 1, and the lower packer 15 has a closed iron pipe 14, a flower pipe 11 is connected between the central through conduit 1 and the closed iron pipe 14, and a water outlet is provided on the flower pipe for injecting pressurized water into the test section, the upper packer 2 and the lower packer 15 are connected through a packer connecting pipe 13, and the packer connecting pipe 13 is used to inject water or oil into the lower packer 15, and the packer connecting pipe 13 can be a rubber hose; a guide rail 12 and two guide rods 10 parallel to the flower pipe 11 are provided between the upper packer 2 and the lower packer 15, a slider 16 is penetrated on the guide rod 10 and the guide rail 12 through a guide rod hole 17 and a guide rail hole 18, and the guide rail 12 is a rack.

[0019] The slider 16 is annular or C-shaped, and the center of the slider 16 has a hollow structure for the flower tube 11 to pass through. The edges of the upper and lower surfaces of the slider 16 are both provided with a slide groove 21, which is a circle or arc shape surrounding the flower tube 11, and a tooth 27 is provided on the edge of the slider; the slider 16 is also provided with a slider gear 20 meshing with the rack of the guide rail 12, and the slider 16 is also provided with a slider motor 19 for driving the slider gear 20. The slider motor 19 preferably adopts an outer rotor motor, and the slider motor 19 is fixedly connected to the slider gear 20. The slider motor 19 is controlled by a remote control module 4, and the remote control module 4 is arranged at the bottom of the upper packer 2. The control line of the remote control module 4 is led to the controller on the ground surface through the packer line groove 3 of the upper packer. The staff on the ground surface controls the forward or reverse rotation of the slider motor 19 through the remote control module 4, drives the slider gear 20 to rotate forward or reverse, and makes the slider 16 rise or fall along the guide rod 10. The notch 26 of the C-shaped slider 16 can be used to avoid the packer connecting pipe 13 .

[0020] The camera mounting seat 6 is C-shaped and is clamped on the edge of the slider 16. The camera mounting seat 6 is provided with a roller 22 located in the slide groove 21. The camera mounting seat 6 is also provided with a driving gear 24 meshing with the teeth 27 of the slider 16. The camera mounting seat 6 is also provided with a driving motor 23 for driving the driving gear 24. The driving motor 23 preferably adopts an outer rotor motor, and the driving motor 23 is fixedly connected to the driving gear 24; a transparent protective cover 8 is provided at the bottom of the camera mounting seat 6, a camera 7 is provided in the transparent protective cover 8, and a compass 9 for positioning is provided at the bottom of the transparent protective cover 8; the electric wires of the driving motor 23 and the data cables of the camera 7 are led out from the mounting seat wire groove 25 of the camera mounting seat 6 and then wound on the reel 5. The reel 5 is arranged at the bottom of the upper packer 1, and the electric wires and data cables are led to the controller on the surface through the reel 5 and the packer wire groove 3 of the upper packer. The staff controls the rotation of the driving motor 23 on the surface, thereby driving the driving gear 24 to rotate. The edge teeth of the driving gear 24 and the slider 16 mesh so that the camera mounting seat 6 moves along the slide groove 21 of the slider, thereby driving the camera 7 to move around the flower tube 11 to achieve a complete observation of the hole wall. The camera 7 preferably adopts a wide-angle camera or a panoramic camera, so that the camera does not need to go around the flower tube 11 to observe the entire hole wall, leaving no blind spots that cannot be observed. The reel 5 has a coil spring, so that the wires and data cables can automatically follow the movement of the camera mounting seat 6.

[0021] In actual use, the whole system is placed into the test hole using equipment such as a drill rod or a wire rope, and the location of the test section can be determined based on the conditions of the borehole wall rock mass captured by the camera. After the test section is selected, water or oil is injected into the upper and lower packers to form a closed rock section, and the test begins. Water is injected through the pressurized section flower pipe 11 to form pressure on the test section rock mass. When a decrease in water pressure is detected, that is, tiny cracks have occurred in the test section rock mass, and water flows into the rock mass, the slider 16 is controlled to move up and down on the ground, and the camera mounting seat 6 moves circumferentially. The direction of water flow is observed through the camera 7, and the direction is determined in combination with the compass 9 to determine the direction of the minimum plane principal stress of the rock mass.

[0022] The embodiments of the present invention are described above in conjunction with the accompanying drawings. In the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. For the convenience of description, the words "upper" and "lower" appearing in the above only indicate that the upper and lower directions are consistent with the accompanying drawings themselves, and do not limit the structure. The present invention is not limited to the above-mentioned specific embodiments, which are merely illustrative and not restrictive. Under the enlightenment of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the present invention and the claims, which all belong to the protection scope of the present invention.

Claims

1. A device for real-time observation of rock mass cracks during hydraulic fracturing in-situ stress testing, comprising: An upper packer (2), a lower packer (15), and a flower tube (11) and a packer connecting pipe (13) connected between the upper packer (2) and the lower packer (15), characterized in that they also include: a slider (16), a guide rod (10), a camera (7) and a camera mounting seat (6), wherein the guide rod (10) is arranged between the upper packer (2) and the lower packer (15) and is parallel to the flower tube (11), the slider (16) is arranged on the guide rod (10) and can slide along the guide rod (10), the edges of the upper surface and the lower surface of the slider (16) are both provided with a slide groove (21), the slide groove (21) is an arc or a circle surrounding the flower tube (11), and the edge of the slider (16) is provided with a teeth (27), the camera mounting seat (6) is C-shaped and mounted on the edge of the slider (16), the camera mounting seat (6) is provided with a roller (22) located in a slide groove (21) on the upper surface of the slider and a roller (22) located in a slide groove (21) on the lower surface of the slider, the camera mounting seat (6) is further provided with a driving gear (24) meshing with the teeth (27) of the slider (16), the camera mounting seat (6) is further provided with a driving motor (23) for driving the driving gear (24), a transparent protective cover (8) is provided at the bottom of the camera mounting seat (6), a camera (7) is provided in the transparent protective cover (8), and a compass (9) for positioning is provided at the bottom of the transparent protective cover (8); A guide rail (12) parallel to the guide rod (10) is connected between the upper packer (2) and the lower packer (15), the guide rail (12) passes through the guide rail hole (18) of the slider (16), the guide rail (12) is a rack, a slider gear (20) meshing with the guide rail (12) is provided in the slider (16), a slider motor (19) for driving the slider gear (20) is also provided in the slider (16), the slider motor (19) is controlled by a remote control module (4), the remote control module (4) is provided at the bottom of the upper packer (2), and a control line of the remote control module (4) is led to a controller on the surface through the upper packer (2); The center of the slider (16) has a hollow structure for the flower tube (11) to pass through.

2. The device for real-time observation of rock cracks in a hydraulic fracturing ground stress test according to claim 1, characterized in that: The electric wires of the driving motor (23) and the data wires of the camera (7) are led out from the camera mounting seat (6) and wound on a wire reel (5). The wire reel (5) is arranged at the bottom of the upper packer (2). The electric wires and the data wires are led to a controller on the surface through the wire reel (5) and the upper packer (2).

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