Optimization Analysis on Hydraulic Fracturing Crossing Borehole Layout and Its Application in Coal Mine
LI Dong
GUO Chenye
QIN Le
HUANG Changwen
TANG Yude
ZHOU Xiaolin
Abstract：To resolve the problem of gas drainage difficulty in soft coal seam with low permeability in Chongqing area, a new technology by hydraulic fracturing across coal seams was proposed, it was concluded from the analysis that the process of the permeability enhancement included the original crack expansion and the secondary crack formation in the tensile stress concentration area produced at the crack tip. Study was made on the variation law of the plastic failure zone of the coal body by hydraulic fracturing across seams with the pressure of the injected high-pressure water with the help of numerical simulation. It was found that the fracture initiation pressure of No. 7 coal seam in Fengchun Coal Mine was 33 ~35 MPa and the extension pressure was slightly lower than the initiation pressure. The exponential curve of the hydraulic fracturing radius and the injection pressure was fitted out, which was applied to gas pre-drainage engineering in a floor roadway. The application results showed that the effective range of hydraulic fracturing along the strike and inclination respectively reached 60 m and 50 m, the permeability of coal seam raised by 195 ~370 times, the gas drainage volume increased by 3. 5 times and the gas drainage concentration increased by 5 times.
Keywords：coal seam with low gas permeabilitycrossing boreholehydraulic fracturingborehole layoutpermeability enhancement
Publication Date：2015-01-01
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：6( 63-67,75 )