Experimental Study on Coal Seam Fracturing Based on Hydrodynamic Horizontal Slitting-CO ₂ Blasting Collaboration

Area of Science:

• Mining Engineering
• Geotechnical Engineering
• Petroleum Engineering

Background:

• Deep coal mining faces complex geological conditions, limiting single permeability enhancement technologies.
• Existing methods for coal seam gas permeability enhancement are often insufficient for deep mining applications.

Purpose of the Study:

• To develop and evaluate a novel gas-liquid two-phase comprehensive action coal seam permeability enhancement technology.
• To address the limitations of single permeability enhancement techniques in deep, complex coal seams.

Main Methods:

• Utilized hydraulic horizontal slitting to create a pressure-relief free surface.
• Employed CO2 fracturing and permeability technology to synergize pressure relief and permeability.
• Conducted simulation experiments on similar models to analyze crack expansion.
• Applied digital image correlation techniques to examine displacement field distribution.
• Used COMSOL Multiphysics for coal body displacement analysis and simulation validation.

Main Results:

• Delamination cracks between the roof slab and coal seam were observed to inhibit radial crack extension.
• Hydraulic horizontal slits created unsupported coal bodies, leading to horizontal and radial crack formation.
• CO2 blasting induced further crack expansion and generated new radial cracks, forming a complex network.
• Observed regular changes in y-axis displacement above the slit, decreasing from the center.

Conclusions:

• The integrated hydraulic horizontal slit-CO2 blasting technology effectively enhances coal seam permeability by creating a complex fracture network.
• This gas-liquid two-phase approach offers a promising solution for efficient deep coal seam mining.
• The study validates the synergistic effects of pressure relief and fracturing in improving coal permeability.