Multi-cluster hole sealing device and method for true triaxial hydraulic fracturing test

Abstract

The invention provides a true triaxial hydraulic fracturing test multi-cluster hole sealing device and method. The multi-cluster hole sealing device for the true triaxial hydraulic fracturing test comprises a screw rod, a plurality of hole sealing devices and a plurality of hole sealing devices, the multiple cone parts are arranged on the peripheral face of the screw rod, the peripheral contour of the cross section of each cone part is circular, the outer diameter of each cone part is larger than or equal to the outer diameter of the screw rod, the outer diameter of each cone part is decreased upwards, and at least one cone part is arranged on each of the two sides of each first outlet in the vertical direction; at least one cone part is arranged between every two adjacent first outlets in the vertical direction; and the multiple expansion rings are arranged on the upper portions of the multiple cone parts in a sleeving mode in a one-to-one correspondence mode, and when the cone parts move upwards relative to the corresponding expansion rings, the outer diameters of the expansion rings can be increased. Therefore, the multi-cluster hole sealing device for the true triaxial hydraulic fracturing test has the advantage that the drilled hole can be conveniently sealed so that hydraulic fracturing can be carried out.

Description

Technical Field

[0001] The invention relates to the technical field of rock fracturing tests, and in particular to a true triaxial hydraulic fracturing test multi-cluster sealing device and method. Background Art

[0002] Hydraulic fracturing technology uses high pressure to inject fracturing fluid into underground rock formations to form cracks, thereby improving the seepage capacity and extraction efficiency of oil and gas. The hydraulic fracturing true triaxial test simulates the actual stress environment that underground rocks are subjected to by applying stress in different directions to the rock sample on a triaxial loader. Then, through drilling, the high-pressure pipe is pre-buried in the specified position and the hole is sealed, and high-pressure fracturing fluid is injected into the rock sample to explore the expansion law of the cracks and the mechanical behavior of the rock. In related technologies, in a single borehole, fracturing fluid is usually injected in stages through a sealer to form multiple fracture clusters. The efficiency of the sealer to inject fracturing fluid in stages is low, which makes the hydraulic fracturing test less efficient. Summary of the invention

[0003] The present invention aims to solve one of the technical problems in the related art at least to a certain extent. To this end, an embodiment of the present invention provides a multi-cluster sealing device and method for a true triaxial hydraulic fracturing test.

[0004] The multi-cluster sealing device for true triaxial hydraulic fracturing test according to the embodiment of the present invention comprises:

[0005] A screw, the screw extending in the up-down direction, the outer peripheral contour of the cross section of the screw is circular, the screw having a plurality of guide channels arranged at intervals, a first inlet of the guide channel being opened at the top of the screw, a first outlet of the guide channel being opened on the outer peripheral surface of the middle and lower part of the screw, and a plurality of the first outlets being arranged at intervals in the up-down direction;

[0006] A plurality of vertebral bodies, wherein the plurality of vertebral bodies are arranged on the outer peripheral surface of the screw, the outer peripheral contour of the cross section of the vertebral body is circular, the outer diameter of the vertebral body is greater than or equal to the outer diameter of the screw, and the outer diameter of the vertebral body decreases upward, each of the first outlets is provided with at least one vertebral body on both sides in the up-down direction, and at least one vertebral body is provided between two adjacent first outlets in the up-down direction;

[0007] A plurality of expansion rings are sleeved on the upper parts of the plurality of vertebral bodies in a one-to-one correspondence, and when the vertebral bodies move upward relative to the corresponding expansion rings, the outer diameters of the expansion rings can be increased.

[0008] Therefore, the multi-cluster sealing device for true triaxial hydraulic fracturing test according to the embodiment of the present invention has the advantage of being convenient for sealing the borehole for hydraulic fracturing.

[0009] In some embodiments, a plurality of positioning rings are disposed on the outer circumference of the screw rod, and the plurality of positioning rings are correspondingly located above the plurality of vertebral bodies, and the plurality of positioning rings are correspondingly abutted against the top surfaces of the plurality of expansion rings.

[0010] In some embodiments, the expansion ring is elastically deformable.

[0011] In some embodiments, the diameter of the inner annular surface of the lower portion of the expansion ring increases downward.

[0012] In some embodiments, the outer diameters of the outer circumferences of the expansion rings are equal;

[0013] Alternatively, the diameter of the outer annular surface of the upper portion of the expansion ring is smaller than or equal to the diameter of the outer annular surface of the lower portion of the expansion ring, and the diameter of the outer annular surface of the lower portion of the expansion ring increases downward.

[0014] In some embodiments, the first outlet is oriented horizontally;

[0015] The top of the screw has an upper end surface facing upward, and the first inlets of the plurality of guide channels are all opened on the upper end surface of the screw.

[0016] In some embodiments, the screw has two guide channels, and the first outlets of the two guide channels are arranged in opposite directions in a horizontal direction.

[0017] In some embodiments, the top of the screw is provided with an external thread, the top of the screw is sleeved with a gasket for abutting against the opening of the drilled hole, and the top of the screw is provided with a nut connected to the external thread thereon.

[0018] The present invention also proposes a true triaxial hydraulic fracturing test multi-cluster sealing method using the true triaxial hydraulic fracturing test multi-cluster sealing device, comprising the following steps:

[0019] The plurality of expansion rings are sleeved on the plurality of vertebral bodies on the screw rod in a one-to-one correspondence;

[0020] Put the true triaxial hydraulic fracturing test multi-cluster sealing device downward into the borehole;

[0021] The screw is rotated so that the plurality of vertebral bodies on the screw can move upward relative to the expansion ring, thereby making the outer peripheral surface of the expansion ring abut against the wall surface of the borehole.

[0022] In some embodiments, the top of the screw is provided with an external thread, the top of the screw is sleeved with a gasket for abutting against the orifice of the drilled hole, and the top of the screw is provided with a nut connected to the external thread thereon;

[0023] The screw rod can be driven to rotate by rotating the nut. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Schematic diagram of a multi-cluster sealing device for a true triaxial hydraulic fracturing test according to an embodiment of the present invention.

[0025] Figure 2 4 is a cross-sectional view of a multi-cluster sealing device for a true triaxial hydraulic fracturing test according to an embodiment of the present invention.

[0026] Figure 3 3 is a diagram showing the use status of a multi-cluster sealing device for a true triaxial hydraulic fracturing test according to an embodiment of the present invention.

[0027] Figure numerals: 1. screw rod, 2. guide channel, 3. cone body, 4. expansion ring, 5. positioning ring, 6. gasket, 7. nut. DETAILED DESCRIPTION

[0028] Embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to be used to explain the present invention, but should not be understood as limiting the present invention.

[0029] The following describes a true triaxial hydraulic fracturing test multi-cluster sealing device according to an embodiment of the present invention with reference to the accompanying drawings. Figures 1 to 3 As shown, the true triaxial hydraulic fracturing test multi-cluster sealing device according to an embodiment of the present invention includes a screw 1, a plurality of vertebral bodies 3 and a plurality of expansion rings 4.

[0030] The screw 1 extends in the up-down direction, and the outer peripheral profile of the cross section of the screw 1 is circular. The screw 1 has a plurality of diversion channels 2 arranged at intervals, the first inlet of the diversion channel 2 is opened at the top of the screw 1, the top of the screw 1 has an upper end surface facing the upper side, and the first inlets of the plurality of diversion channels 2 are all opened on the upper end surface of the screw 1. The first outlet of the diversion channel 2 is opened on the outer peripheral surface of the middle and lower part of the screw 1, and the plurality of first outlets are arranged at intervals in the up-down direction. Specifically, the first outlet is oriented in the horizontal direction. Thus, after the screw 1 is fixed in the borehole, the fracturing fluid of the preset pressure can be introduced into different diversion channels 2, and the fracturing fluid in different diversion channels 2 can be discharged from different first outlets, so as to form hydraulic fracturing cracks of different heights, and the plurality of diversion channels 2 can form multiple clusters of cracks. For example, the length of the screw 1 is 300 mm, and the outer diameter of the screw 1 is 25 mm. The diameter of the diversion channel 2 is 5 mm.

[0031] A plurality of vertebral bodies 3 are arranged on the outer peripheral surface of the screw 1, and the outer peripheral contour of the cross section of the vertebral body 3 is circular. The outer diameter of the vertebral body 3 is greater than or equal to the outer diameter of the screw 1, and the outer diameter of the vertebral body 3 decreases upward. A plurality of expansion rings 4 are sleeved on the upper part of the plurality of vertebral bodies 3 in a one-to-one correspondence, and the outer diameter of the expansion ring 4 can be increased when the vertebral body 3 moves upward relative to the corresponding expansion ring 4. Specifically, the vertebral body 3 is a conical structure with a diameter decreasing upward, and the vertebral body 3 and the screw 1 are integrally formed. The expansion ring 4 is a circular ring, and the shape and maximum outer diameter of the expansion ring 4 are adapted to the shape and diameter of the borehole so that the maximum outer diameter of the expansion ring 4 is slightly smaller than the diameter of the borehole. After the true triaxial hydraulic fracturing test multi-cluster sealing device according to the embodiment of the present invention is placed in the borehole, the screw 1 drives the vertebral body 3 to move upward relative to the corresponding expansion ring 4, so that the outer diameter of the expansion ring 4 can be increased, so that the expansion ring 4 can abut against the wall of the borehole, so that the expansion ring 4 can fill the gap between the vertebral body 3 and the borehole, and then the space between the borehole and the screw 1 is isolated in the up and down directions. Thereby, a good sealing effect can be formed, thereby preventing the leakage of the fracturing fluid.

[0032] Each first outlet is provided with at least one vertebral body 3 on both sides in the vertical direction, and at least one vertebral body 3 is provided between two adjacent first outlets in the vertical direction. Thus, multiple vertebral bodies 3 and multiple expansion rings 4 can be matched to block the first outlet in the vertical direction, prevent the fracturing fluid discharged from the first outlet from being discharged from the upper or lower part of the borehole, and avoid mutual influence between the diversion channels 2, so as to facilitate the sealing of the borehole. This facilitates hydraulic fracturing of rocks, so that fracturing tests at multiple positions can be flexibly performed in a single borehole.

[0033] Therefore, the multi-cluster sealing device for true triaxial hydraulic fracturing test according to the embodiment of the present invention has the advantage of being convenient for sealing the borehole for hydraulic fracturing.

[0034] like Figures 1 to 3 As shown, in some embodiments, the outer peripheral surface of the screw rod 1 is provided with a plurality of positioning rings 5, and the plurality of positioning rings 5 ​​are correspondingly located above the plurality of vertebral bodies 3, and the plurality of positioning rings 5 ​​are correspondingly abutted against the top surfaces of the plurality of expansion rings 4. Thus, the expansion rings 4 can be easily positioned so that the vertebral bodies 3 can move upward relative to the corresponding expansion rings 4.

[0035] In some embodiments, the top of the screw rod 1 is provided with an external thread, the top of the screw rod 1 is sleeved with a gasket 6 for abutting against the hole of the drilled hole, and the top of the screw rod 1 is provided with a nut 7 connected to the external thread thereon. Thus, the operator can gradually tighten the nut 7, and as the nut 7 rotates and abuts against the gasket 6 at the drilled hole, the nut 7 drives the screw rod 1 to rotate and move upward. As a result, a large pressure effect can be formed between the vertebral body 3 and the expansion ring 4, and this pressure causes the outer peripheral surface of the expansion ring 4 to generate friction with the hole wall of the drilled hole and the vertebral body 3, so that the vertebral body 3 rotates upward relative to the expansion ring 4, thereby realizing the self-locking function and ensuring the sealing effect.

[0036] In some embodiments, the expansion ring 4 may be elastically deformed, thereby facilitating the expansion ring 4 to expand outward. For example, the expansion ring 4 has an expansion groove opening toward the lower side.

[0037] In some embodiments, the diameter of the inner ring surface of the lower portion of the expansion ring 4 increases downward, so that the inner ring surface of the lower portion of the expansion ring 4 can be easily adapted to the outer surface of the vertebral body 3. Specifically, the inner and outer contours of the cross section of the lower portion of the expansion ring 4 are both circular.

[0038] In some embodiments, the outer diameters of the outer circumferences of the expansion rings 4 are equal. Specifically, the outer diameters of the outer circumferences of the expansion rings 4 match the diameters of the boreholes, so that the outer circumferences of the expansion rings 4 are in contact with the walls of the boreholes.

[0039] like Figure 2 As shown, in some embodiments, the diameter of the outer annular surface of the upper portion of the expansion ring 4 is less than or equal to the diameter of the outer annular surface of the lower portion of the expansion ring 4, and the diameter of the outer annular surface of the lower portion of the expansion ring 4 increases downward. Specifically, the diameters of the outer annular surfaces of the upper portions of the expansion ring 4 are equal.

[0040] In some embodiments, the screw 1 has two guide channels 2, the first outlets of the two guide channels 2 are arranged back to back in the horizontal direction, the first outlets of the two guide channels 2 are arranged at intervals in the up and down directions, and two vertebral bodies 3 and two expansion rings 4 are arranged between the first outlets of the two guide channels 2.

[0041] The present invention also proposes a true triaxial hydraulic fracturing test multi-cluster sealing method using the true triaxial hydraulic fracturing test multi-cluster sealing device according to the embodiment of the present invention. The true triaxial hydraulic fracturing test multi-cluster sealing method according to the embodiment of the present invention comprises the following steps:

[0042] Multiple expansion rings 4 are sleeved on multiple vertebral bodies 3 on the screw 1 in a one-to-one correspondence. Before sealing the hole, the borehole needs to be thoroughly inspected to remove debris, mud, etc. in the hole to ensure that the hole wall is clean and smooth. The expansion ring 4 is assembled on the screw 1, and the flow guide channel 2 is ensured to be unobstructed to avoid blockage that affects the flow of the fracturing fluid.

[0043] Put the true triaxial hydraulic fracturing test multi-cluster sealing device downward into the borehole. Specifically, the test personnel carefully put the true triaxial hydraulic fracturing test multi-cluster sealing device into the borehole, ensuring that the screw 1 and the expansion ring 4 are installed in the accurate position to achieve the best sealing effect.

[0044] The screw rod 1 is rotated so that the multiple vertebral bodies 3 on the screw rod 1 can move upward relative to the expansion ring 4, so that the outer peripheral surface of the expansion ring 4 can abut against the wall surface of the borehole. Specifically, the operator gradually tightens the nut 7 and can rotate the nut 7 to drive the screw rod 1 to rotate.

[0045] By using the multi-cluster sealing device for true triaxial hydraulic fracturing test according to the embodiment of the present invention, the outlet of each diversion channel 2 is connected to the rock sample borehole. Since each diversion channel 2 is set independently, interference between each other is avoided, so that fracturing tests at multiple positions can be flexibly performed in a single borehole. The flexibility and efficiency of the research are greatly improved, allowing operators to perform fracturing at fixed points where needed, thereby meeting different experimental requirements.

[0046] In the description of the present invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0047] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0048] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection, an electrical connection, or communication with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0049] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0050] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" etc. mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0051] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A multi-cluster sealing device for true triaxial hydraulic fracturing test, characterized in that: include: A screw, the screw extending in the up-down direction, the outer peripheral contour of the cross section of the screw is circular, the screw having a plurality of guide channels arranged at intervals, a first inlet of the guide channel being opened at the top of the screw, a first outlet of the guide channel being opened on the outer peripheral surface of the middle and lower part of the screw, and a plurality of the first outlets being arranged at intervals in the up-down direction; A plurality of vertebral bodies, wherein the plurality of vertebral bodies are arranged on the outer peripheral surface of the screw, the outer peripheral contour of the cross section of the vertebral body is circular, the outer diameter of the vertebral body is greater than or equal to the outer diameter of the screw, and the outer diameter of the vertebral body decreases upward, each of the first outlets is provided with at least one vertebral body on both sides in the up-down direction, and at least one vertebral body is provided between two adjacent first outlets in the up-down direction; A plurality of expansion rings are sleeved on the upper parts of the plurality of vertebral bodies in a one-to-one correspondence, and when the vertebral bodies move upward relative to the corresponding expansion rings, the outer diameters of the expansion rings can be increased.

2. The true triaxial hydraulic fracturing test multi-cluster sealing device according to claim 1, characterized in that: The outer peripheral surface of the screw rod is provided with a plurality of positioning rings, the plurality of positioning rings are located above the plurality of vertebral bodies in a one-to-one correspondence, and the plurality of positioning rings are in a one-to-one correspondence with the top surfaces of the plurality of expansion rings.

3. The true triaxial hydraulic fracturing test multi-cluster sealing device according to claim 2, characterized in that: The expansion ring can be elastically deformed.

4. The true triaxial hydraulic fracturing test multi-cluster sealing device according to claim 2, characterized in that: The diameter of the inner annular surface of the lower portion of the expansion ring increases downward.

5. The true triaxial hydraulic fracturing test multi-cluster sealing device according to claim 4, characterized in that: The outer diameters of the outer peripheral surfaces of the expansion rings are equal; Alternatively, the diameter of the outer annular surface of the upper portion of the expansion ring is smaller than or equal to the diameter of the outer annular surface of the lower portion of the expansion ring, and the diameter of the outer annular surface of the lower portion of the expansion ring increases downward.

6. The true triaxial hydraulic fracturing test multi-cluster sealing device according to any one of claims 1 to 5, characterized in that: The first outlet is oriented in a horizontal direction; The top of the screw has an upper end surface facing upward, and the first inlets of the plurality of guide channels are all opened on the upper end surface of the screw.

7. The true triaxial hydraulic fracturing test multi-cluster sealing device according to claim 6, characterized in that: The screw has two guide channels, and the first outlets of the two guide channels are arranged in opposite directions in a horizontal direction.

8. The true triaxial hydraulic fracturing test multi-cluster sealing device according to claim 1, characterized in that: The top of the screw rod is provided with an external thread, the top of the screw rod is sleeved with a gasket for abutting against the hole of the drill hole, and the top of the screw rod is provided with a nut connected with the external thread thereon.

9. A true triaxial hydraulic fracturing test multi-cluster sealing method using the true triaxial hydraulic fracturing test multi-cluster sealing device according to any one of claims 1 to 8, characterized in that: The following steps are involved: The plurality of expansion rings are sleeved on the plurality of vertebral bodies on the screw rod in a one-to-one correspondence; Put the true triaxial hydraulic fracturing test multi-cluster sealing device downward into the borehole; The screw is rotated so that the plurality of vertebral bodies on the screw can move upward relative to the expansion ring, thereby making the outer peripheral surface of the expansion ring abut against the wall surface of the borehole.

10. The multi-cluster sealing method for true triaxial hydraulic fracturing test according to claim 9, characterized in that: The top of the screw is provided with an external thread, the top of the screw is sleeved with a gasket for abutting against the hole of the drill hole, and the top of the screw is provided with a nut connected with the external thread thereon; The screw rod can be driven to rotate by rotating the nut.

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