Stress Relief and Stimulation of Coal Reservoir by Hydraulic Slotting

Abstract

Coal seam permeability is one of the key factors influencing the gas extraction efficiency, which is of great significance to reduce coal and gas dynamic disasters in gassy coal mines. Hydraulic slotting technique is an effective method to stimulate the coal reservoir, but the selection of slotting key parameters has great impact on gas extraction efficiency. For this reason, the hydraulic slotting model was established by using FLAC3D software to analyze the stress distribution before and after slotting. Then, the influence of borehole diameter, slotting width, and slotting length on coal seam stress relief is also discussed. The results show that the slotting width has a great influence on the stress relief of the coal seam, while the borehole diameter and slotting length have no obvious influence on that. Based on the results of numerical simulation, field tests were carried out in Sangshuping NO.2 coal mine. The results show that the coal seam stress can be fully released, resulting in the improvement of coal seam permeability. The gas extraction efficiency can be highly enhanced by hydraulic slotting. This research achievement provides the guidance basis for high-stress water jet slotting technology with adaptive selection of slotting parameters in different geological conditions.

Analysis of Influence of Ultra-High Pressure Water Jet Cutting Pressure Sequence on Pressure Relief and Reflection Improvement of Coal Seam

“…It is proposed that U-shaped steel telescopic support erection and backwall flling are used to control the surrounding rock of goaf mining in the process of roadway excavation, and the on-site monitoring results also meet the engineering requirements. Te research results can provide guidance for roadway design of goaf under similar mining geological conditions [35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50][51].…”

Coal–Rock Dynamic Disaster Prevention Mechanism Based on the Dual Loads of Dynamic Barrier and Static Pressure Relief by Hydraulic Slotting

“…The fully mechanized mining support, slotted coal, and nonslotted coal form a static indeterminacy system. When the roof settlement height of the slotted section is Δ h , the abutment pressure of the slotted section is , F normals = 4 7 σ normals l − 64 normalΔ italichEL H 2 3 7 l 3 where E is the rigidity of coal, Pa; L is the length of the borehole slotting section, m; H 2 is the height of the direct roof, m; l is the range of the working face slotting area, m; and σ s is the roof pressure of the slotting section, Pa.…”

Optimization of Destressing Parameters of Water Jet Slits in Rock Burst Coal Seams for Deep Mining

“…The high-pressure water jet (HPWJ) technique has showed its effectiveness in preventing rock bursts in the deep mining coal seam [9][10][11]. Based on the high-pressure water as the power to impact the coal seam, the uniform annular groove in the track around a particular plastic failure zone as well as the weakening area will then be generated [12][13][14]. Many scholars have studied the coal-breaking mechanism of the HPWJ.…”