Abstract: A method for shale gas exploitation includes performing horizontal drilling operation on an area to be constructed, forming a crack around a horizontal drill hole wall by shaped charge perforation; expanding the crack around a horizontal hole hydraulic fracturing, and extracting methane gas after a fracturing fluid is discharged; after methane gas is reduced, performing in-situ combustion explosion fracturing on the methane involved in horizontal drilling; thereafter continuing to expand the crack in the horizontal drill hole such that methane continues to seep out, and continuing extracting methane; repeating combustion explosion fracturing and extraction operations, so as to increase combustion explosion cracking permeability, and greatly enhance the exploitation effect of shale gas. The method is suitable for fracturing reconstruction of unconventional oil and gas reservoirs such as shale gas reservoirs, coal seam gas reservoirs and tight sandstone gas reservoirs.

Abstract: A liquid explosive for in-situ explosive fracturing in low-permeability oilfields and application thereof are provided. The liquid explosive includes raw materials in parts by mass: a main explosive with positive oxygen balance, a guest regulator and isolation microcapsules; the main explosive with the positive oxygen balance includes raw materials in parts by mass: monomethylamine nitrate, ammonium nitrate, sodium nitrate, water, guar gum, sodium nitrite, a high-temperature resistant regulator with a low detonation velocity and a surfactant; the guest regulator includes raw materials in parts by mass: a reducing agent and a density regulator; the isolation microcapsules include raw materials in parts by mass: porous hollow microbeads, a pore plugging agent and wall materials of pressure-resistant microcapsules; the guest regulator exists in the porous hollow microbeads of the isolation microcapsules.

Abstract: A liquid explosive for in-situ explosive fracturing in low-permeability oilfields and application thereof are provided. The liquid explosive includes raw materials in parts by mass: a main explosive with positive oxygen balance, a guest regulator and isolation microcapsules; the main explosive with the positive oxygen balance includes raw materials in parts by mass: monomethylamine nitrate, ammonium nitrate, sodium nitrate, water, guar gum, sodium nitrite, a high-temperature resistant regulator with a low detonation velocity and a surfactant; the guest regulator includes raw materials in parts by mass: a reducing agent and a density regulator; the isolation microcapsules include raw materials in parts by mass: porous hollow microbeads, a pore plugging agent and wall materials of pressure-resistant microcapsules; the guest regulator exists in the porous hollow microbeads of the isolation microcapsules.

Abstract: The present disclosure relates to a speaker and a magnetic circuit system thereof. The speaker includes a housing and at least one magnetic circuit system and at least one vibration system arranged in the housing. The at least one vibration system includes at least one layer of drive circuit configured to generate mechanical motion under the action of a magnetic field of the at least one magnetic circuit system, and a diaphragm driven by the at least one layer of drive circuit. The at least one layer of driving circuit is mounted to the diaphragm and has a planar shape. Since the driving circuit of the vibration system has a planar shape, the thickness of the speaker of the present disclosure can be effectively reduced.

Abstract: An in-situ methane explosion shaped charge perforating device with a molecular sieve is provided and includes a body, an end of the body is fixedly connected to the molecular sieve, two sides of the molecular sieve are fixedly connected to two baffles respectively, each baffle is embedded with several first check valves inside, an end of the body far away from the molecular sieve is fixedly connected to a fixing plate, a center of the fixing plate is embedded with an ignition device, a bottom of the fixing plate is embedded with a concentration sensor, a portion of the fixing plate between the ignition device and the concentration sensor is formed with an air extracting hole, inner walls of a top and a bottom of the body are symmetrically embedded with second check valves, and the ignition device and the concentration sensor are electrically connected to an external controller.

Abstract: An in-situ methane explosion shaped charge perforating device with a molecular sieve is provided and includes a body, an end of the body is fixedly connected to the molecular sieve, two sides of the molecular sieve are fixedly connected to two baffles respectively, each baffle is embedded with several first check valves inside, an end of the body far away from the molecular sieve is fixedly connected to a fixing plate, a center of the fixing plate is embedded with an ignition device, a bottom of the fixing plate is embedded with a concentration sensor, a portion of the fixing plate between the ignition device and the concentration sensor is formed with an air extracting hole, inner walls of a top and a bottom of the body are symmetrically embedded with second check valves, and the ignition device and the concentration sensor are electrically connected to an external controller.

Abstract: The present disclosure relates to a speaker and a magnetic circuit system thereof. The speaker includes a housing and at least one magnetic circuit system and at least one vibration system arranged in the housing. The at least one vibration system includes at least one layer of drive circuit configured to generate mechanical motion under the action of a magnetic field of the at least one magnetic circuit system, and a diaphragm driven by the at least one layer of drive circuit. The at least one layer of driving circuit is mounted to the diaphragm and has a planar shape. Since the driving circuit of the vibration system has a planar shape, the thickness of the speaker of the present disclosure can be effectively reduced.

Abstract: A liquid nitrogen cyclic freeze-thaw permeability-improvement gas drainage method based on horizontal directional boreholes comprises: first constructing a main borehole at an intake roadway or a return roadway, a low-level roadway and a high-level roadway, after a drill bit reaches a pre-set target position of a coal bed, uniformly and directionally constructing a plurality of branch boreholes along a horizontal direction of the coal bed, injecting water to the coal bed, opening a valve, filling the main boreholes with liquid nitrogen, rapidly freezing the water injected into the branch boreholes and the periphery of the coal bed, and stopping injecting the nitrogen when an average temperature of a pre-permeability-improvement area monitored by a temperature measuring hole is lowered to ?2° C. or lower.

Abstract: A liquid nitrogen cyclic freeze-thaw permeability-improvement gas drainage method based on horizontal directional boreholes comprises: first constructing a main borehole at an intake roadway or a return roadway, a low-level roadway and a high-level roadway, after a drill bit reaches a pre-set target position of a coal bed, uniformly and directionally constructing a plurality of branch boreholes along a horizontal direction of the coal bed, injecting water to the coal bed, opening a valve, filling the main boreholes with liquid nitrogen, rapidly freezing the water injected into the branch boreholes and the periphery of the coal bed, and stopping injecting the nitrogen when an average temperature of a pre-permeability-improvement area monitored by a temperature measuring hole is lowered to ?2° C. or lower.

Abstract: Disclosed in the invention is a multi-information coupling prediction method of coal and gas outburst danger, which is achieved by establishing a multi-index coupling prediction model to detect indexes including original gas pressure of a coal layer, the original rock stress, the critical burst gas pressure of a coal sample, the mechanical performance of coal body, the exploit influence, the drilling cutting gas desorption index, the drilling cutting quantity index and the like, therefore to coupling predict the coal and gas outburst danger. By the multi-information coupling prediction method, the information of the coal and gas outburst danger can be fully complemented; the gas and crustal stress outburst danger prediction is carried out; the defects of insufficient complementation information of a single-index and inaccurate prediction are overcome; and the accuracy of the coal and gas outburst danger prediction is improved.

Abstract: Disclosed in the invention is a multi-information coupling prediction method of coal and gas outburst danger, which is achieved by establishing a multi-index coupling prediction model to detect indexes including original gas pressure of a coal layer, the original rock stress, the critical burst gas pressure of a coal sample, the mechanical performance of coal body, the exploit influence, the drilling cutting gas desorption index, the drilling cutting quantity index and the like, therefore to coupling predict the coal and gas outburst danger. By the multi-information coupling prediction method, the information of the coal and gas outburst danger can be fully complemented; the gas and crustal stress outburst danger prediction is carried out; the defects of insufficient complementation information of a single-index and inaccurate prediction are overcome; and the accuracy of the coal and gas outburst danger prediction is improved.