CN-121993082-A - Double-layer packer for hydraulic fracturing of coal mine and testing method thereof

CN121993082ACN 121993082 ACN121993082 ACN 121993082ACN-121993082-A

Abstract

The invention provides a double-layer packer for hydraulic fracturing of a coal mine and a testing method thereof, wherein the double-layer packer comprises a central inner pipe, a first elastic cylinder and a second elastic cylinder, wherein the central inner pipe is axially penetrated, the central inner pipe is provided with at least one water through hole which radially penetrates along the central inner pipe, the first elastic cylinder is sleeved on the central inner pipe and forms a first expansion cavity at the outer side of the central inner pipe, the water through hole is positioned in the first expansion cavity, the second elastic cylinder is sleeved on the central inner pipe and forms a second expansion cavity at the outer side of the central inner pipe, the first expansion cavity is positioned in the second expansion cavity, and a metal net is arranged on the cylinder body of the second elastic cylinder. In the double-layer packer for hydraulic fracturing of the coal mine and the testing method thereof, the hole sealing and pressure maintaining success rate can be guaranteed, the construction efficiency is improved, and the cost of fracturing engineering materials is effectively reduced.

Inventors

ZHENG YANGFA
SUN XIAODONG
LI JIAFENG
WU PENGFEI
LIANG JIAMING
ZHAO KAIKAI

Assignees

中煤科工开采研究院有限公司

Dates

Publication Date: 20260508
Application Date: 20251230

Claims (10)

1. A dual layer packer for hydraulic fracturing of a coal mine, comprising: The central inner pipe is communicated in the axial direction and is provided with at least one water through hole which is communicated in the radial direction of the central inner pipe; The first elastic cylinder is sleeved on the central inner pipe, a first expansion cavity is formed at the outer side of the central inner pipe, and the water through hole is positioned in the first expansion cavity; The second elastic cylinder is sleeved on the central inner pipe, a second expansion cavity is formed outside the central inner pipe, the first expansion cavity is positioned in the second expansion cavity, and a metal net is arranged on the cylinder body of the second elastic cylinder; when the fracturing fluid is introduced into the central inner pipe, the first expansion cavity and the second expansion cavity sequentially expand, and the first elastic cylinder and the second elastic cylinder sequentially push against the inner wall of the rock hole.
2. The dual-layer packer for hydraulic fracturing of coal mine of claim 1, wherein a first end of the first elastic cylinder is fixedly sleeved on the central inner pipe, and a second end of the first elastic cylinder is hermetically and slidably sleeved on the central inner pipe, and wherein the water through hole is positioned between the first end and the second end of the first elastic cylinder.
3. The dual layer packer for hydraulic fracturing of coal mine of claim 2, further comprising: the first sealing gasket is arranged at the second end of the first elastic cylinder, and the first sealing gasket is sleeved on the central inner tube in a sliding mode.
4. The dual layer packer for hydraulic fracturing of coal mine of claim 1, wherein a first end of the second elastic cylinder is fixedly sleeved on the central inner tube, and a second end of the second elastic cylinder is sealingly and slidably sleeved on the central inner tube, wherein the first elastic cylinder is located between the first end and the second end of the second elastic cylinder.
5. The dual layer packer for hydraulic fracturing of coal mine of claim 4, further comprising: The second sealing gasket is arranged at the second end of the second elastic cylinder, and the second sealing gasket is sleeved on the central inner tube in a sliding mode.
6. The dual layer packer for hydraulic fracturing of coal mine of claim 1, further comprising: The first connector is arranged at the first end of the central inner tube and is used for being connected with the constant pressure opener in a threaded mode.
7. The dual layer packer for hydraulic fracturing of coal mine of claim 1, further comprising: and the second joint is arranged at the second end of the central inner pipe and is used for being connected with the fracturing string in a threaded manner.
8. The dual layer packer for hydraulic fracturing of coal mine of claim 1, wherein at least one of said water ports comprises: The first water through holes are arranged on the central inner pipe and are arranged along the radial direction of the central inner pipe, and the first water through holes are positioned in the first expansion cavity; The second water through holes are arranged on the central inner pipe and are arranged along the radial direction of the central inner pipe, and the second water through holes are positioned in the first expansion cavity; The first water through holes and the second water through holes are distributed at intervals along the axial direction of the central inner tube.
9. A method of testing a dual layer packer for hydraulic fracturing of coal mines according to any one of claims 1-8, comprising: s1, connecting a first end of a central inner pipe of the double-layer packer with an oiling device, and plugging a second end of the central inner pipe; S2, placing the plugged double-layer packer in a test pipeline, wherein one end of the test pipeline, which is close to the second end of the central inner pipe, is of a closed structure, and one end of the test pipeline, which is close to the first end of the central inner pipe, is of an open structure; S3, starting the oiling device, controlling the oiling device to inject oil with pressure increasing step by step into the central inner tube along a preset time line, and keeping the pressure of each step for a preset duration time; and S4, recording the pressure and time curve of the double-layer packer, and judging the quality of the double-layer packer according to the recorded pressure and time curve.
10. The method of testing a dual layer packer for hydraulic fracturing of a coal mine of claim 9, further comprising: cutting a gap with a preset length on a second elastic cylinder of the double-layer packer; Steps S1 to S4 are repeated.

Description

Double-layer packer for hydraulic fracturing of coal mine and testing method thereof Technical Field The disclosure relates to the technical field of coal mine underground hydraulic fracturing stratum control, in particular to a double-layer packer for coal mine hydraulic fracturing and a testing method thereof. Background The technology of preventing and controlling the strong rock formation mining pressure by hydraulic fracturing of underground direct drilling and directional drilling of coal mines has been widely used. At present, a single-layer structure hole packer for fracturing in a sleeve in the petroleum industry is used as a reference for a coal mine underground fracturing packing tool, the rubber surface layer of the single-layer structure hole packer is easy to be worn and locally broken, the segmented fracturing success rate of directional long drilling holes cannot be guaranteed, and moreover, the packing tool is frequently replaced to cause low construction efficiency and increase of material cost. Disclosure of Invention The present disclosure aims to solve, at least to some extent, one of the technical problems in the related art. The double-layer packer for hydraulic fracturing of the coal mine and the testing method thereof are provided. In order to achieve the aim, the first aspect of the disclosure provides a double-layer packer for hydraulic fracturing of a coal mine, which comprises a central inner pipe, a first elastic cylinder, a second elastic cylinder and a second elastic cylinder, wherein the central inner pipe is penetrated in the axial direction, at least one water through hole penetrating in the radial direction of the central inner pipe is formed in the central inner pipe, the first elastic cylinder is sleeved on the central inner pipe, a first expansion cavity is formed in the outer side of the central inner pipe, the water through hole is positioned in the first expansion cavity, the second elastic cylinder is sleeved on the central inner pipe, a second expansion cavity is formed in the outer side of the central inner pipe, the first expansion cavity and the second expansion cavity are sequentially expanded, and the first elastic cylinder and the second elastic cylinder are sequentially propped against the inner wall of a rock hole when the central inner pipe is filled with fracturing fluid. Optionally, the first end of the first elastic cylinder is fixedly sleeved on the central inner tube, and the second end of the first elastic cylinder is hermetically and slidably sleeved on the central inner tube, wherein the water through hole is positioned between the first end and the second end of the first elastic cylinder. Optionally, the double-layer packer further comprises a first sealing gasket, wherein the first sealing gasket is arranged at the second end of the first elastic cylinder, and the first sealing gasket is sleeved on the central inner pipe in a sliding manner. Optionally, the first end of the second elastic cylinder is fixedly sleeved on the central inner tube, and the second end of the second elastic cylinder is hermetically and slidably sleeved on the central inner tube, wherein the first elastic cylinder is located between the first end and the second end of the second elastic cylinder. Optionally, the double-layer packer further comprises a second sealing gasket, wherein the second sealing gasket is arranged at the second end of the second elastic cylinder, and the second sealing gasket is sleeved on the central inner pipe in a sliding manner. Optionally, the double-layer packer further comprises a first connector, wherein the first connector is arranged at the first end of the central inner pipe and is used for being connected with a constant pressure opener in a threaded mode. Optionally, the double-layer packer further comprises a second connector, wherein the second connector is arranged at the second end of the central inner pipe and is used for being connected with the fracturing string in a threaded mode. Optionally, the at least one water through hole comprises a first water through hole, a second water through hole and a third water through hole, wherein the first water through hole is arranged on the central inner pipe and is arranged along the radial direction of the central inner pipe, the first water through hole is positioned in the first expansion cavity, the second water through hole is arranged on the central inner pipe and is arranged along the radial direction of the central inner pipe, and the second water through hole is positioned in the first expansion cavity, and the first water through hole and the second water through hole are distributed at intervals along the axial direction of the central inner pipe. A second aspect of the disclosure provides a testing method of a double-layer packer for hydraulic fracturing of a coal mine, which is provided by the first aspect of the disclosure, and comprises the steps of S1, connecting a first e