Coalbed Permeability Enhancement via Thin Slice Mining
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Solution Overview
Problem
Current methods for coalbed permeability-enhancement induced by pressure-relief, such as dense drilling, protective layer mining, and hydraulic fracturing, face limitations including small pressure relief and permeability enhancement range, low universality, poor continuity, and potential safety hazards, especially in deep coal mines with complex geological conditions.
Innovation Solution
A system and method involving the construction of a conventional development roadway and a boundary roadway with a row of boreholes, where an extremely thin slicing cutting device cuts the coal seam between adjacent boreholes, supported by scraper and leading chains, to create a large-scale continuous pressure relief and permeability enhancement, without significant influence from ground stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dense drilling is used for pressure relief, then the pressure relief can be achieved, but the pressure relief range is small and more boreholes are needed leading to large work amount
Solution Approach 1:
The invention segments the coal seam into multiple thin slices (each 0.3-0.8m thick) using multiple boreholes drilled at different depths and angles. Each borehole creates a localized slice removal that collectively achieves large-scale pressure relief, transforming the need for numerous shallow boreholes into fewer deep boreholes with segmented cutting actions.
Solution Approach 2:
The invention transitions from horizontal borehole spacing (2D plane) to vertical depth dimension (3D space). By drilling boreholes at different depths (e.g., 50-100m, 100-150m, 150-200m) and using inclined drilling angles, the same borehole count achieves much larger pressure relief volume by utilizing the vertical dimension.
2Reliability
If protective layer mining is used, then pressure relief can be achieved, but the method requires strict geological conditions and increases work amount
Solution Approach 1:
The borehole slice removal method serves multiple functions: it relieves gas pressure, enhances permeability, and can be applied regardless of whether a protective layer exists. The method works for both thin and thick coal seams by adjusting borehole depth and slicing thickness, making it universally applicable to various geological conditions unlike protective layer mining.
3Reliability
If hydraulic fracturing is used, then pressure relief can be achieved, but the roof and floor of the coal seam are easily damaged
Solution Approach 1:
Instead of injecting high-pressure fluid that can damage surrounding rock, the invention mechanically extracts/removes thin slices of coal seam through borehole cutting devices. This extraction method achieves pressure relief by physically removing material rather than forcing fluid into the formation, thereby avoiding damage to the roof and floor.
4Reliability
If water jet technology is used, then pressure relief and permeability enhancement can be achieved, but the underground work amount is huge
Solution Approach 1:
The invention replaces the complex water jet mechanical system with a simpler mechanical cutting system using rotating cutters or saw blades in boreholes. This substitution eliminates the need for high-pressure water delivery infrastructure and reduces underground work by using direct mechanical slicing through the coal seam in controlled boreholes.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach achieves large-scale continuous pressure relief and permeability enhancement with high universality, simplicity, and safety, suitable for coal seams with high pressure and low permeability, including those with gas outcrops and potential for CO2 storage, while minimizing operational complexity and ground stress impact.
Implementation Method 1
an extremely thin slicing cutting device is arranged in the boundary roadway, and the extremely thin slicing cutting device is located between the slag discharge hole and the guide hole, and the extremely thin slicing cutting device is moved from the boundary roadway to the conventional development roadway for cutting a coal seam
Data Source
AI summary
Provided is a method and system for coalbed permeability-enhancement induced by pressure-relief with mining an extremely thin slice, belonging to the technical field of coalbed permeability-enhancement induced by pressure-relief. The method includes arranging a boundary gateway and a boundary roadway along a mine field boundary, constructing a row of boreholes into the coal seam to run through a conventional development roadway and the boundary roadway, and arranging devices in the conventional development roadway, the boundary roadway, and the row of boreholes to cut the extremely thin stratified coal seam between boreholes, thus creating a mining space in the coal seam, which causes a deformation failure of the coal around the boreholes.