Multi-level Cross Mining Well Pattern for Coal Bed Methane Drainage
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Solution Overview
Problem
Current methods are inadequate for cost-effective and efficient drainage of coal bed methane from dozens of residual mining areas under multilevel cross mining conditions, as they fail to optimize gas drainage from multiple coal beds and result in greenhouse gas emissions.
Innovation Solution
A multi-level cross mining areas surface well pattern deployment method involving the drilling of horizontal and multilateral wells with nitrogen injection for fracturing, allowing simultaneous drainage from multiple abandoned goafs and reconfiguring well patterns to enhance coal bed methane extraction across a mine field.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If current mining and extracting techniques are used for thin middle coal beds, then single coal bed drainage can be achieved, but combined gas drainage from multiple residual mining areas cannot be achieved
Solution Approach 1:
The patent transitions from single-level vertical drainage to multi-level three-dimensional drainage by drilling horizontal wells at different elevations (first horizontal well at upper level, second horizontal well at lower level) connected through a vertical well, enabling simultaneous drainage from multiple residual mining areas that were previously inaccessible
Solution Approach 2:
The patent implements a nested well structure where the vertical well is arranged in the main borehole, and horizontal well branches are arranged in branch boreholes of the multilateral well system, creating a hierarchical nested configuration that enables access to multiple coal beds from a single surface location
2Adaptability or versatility
If multiple horizontal wells are drilled to access dozens of residual mining areas, then comprehensive gas drainage can be achieved, but well pattern complexity and costs increase
Solution Approach 1:
The patent merges multiple drainage functions into a single integrated multilateral well system where one vertical well with multiple horizontal branches can drain gas from multiple residual mining areas simultaneously, replacing the need for numerous separate vertical wells and reducing overall system complexity
Solution Approach 2:
The multilateral well structure serves multiple functions: the vertical well provides access to multiple levels, horizontal branches drain different residual mining areas, and the system can be configured to drain both thin middle coal beds and thick coal beds through the same well pattern
3Ease of manufacture
If thin middle coal beds are left unmined due to technical limitations, then mining costs are reduced, but methane gas accumulates and causes environmental harm
Solution Approach 1:
The patent performs preliminary gas drainage through horizontal wells drilled into thin middle coal beds before mining operations begin, removing accumulated methane gas and reducing environmental hazards in advance of extraction activities
Solution Approach 2:
The horizontal wells act as intermediary structures that access thin middle coal beds without requiring full-scale mining operations, enabling selective gas drainage from these difficult-to-reach areas while avoiding the high costs of complete extraction
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 method enables efficient and cost-effective drainage of coal bed methane from numerous residual mining areas, reducing greenhouse gas emissions and improving gas extraction efficiency across the mine field.
Implementation Method 1
pressing the liquid nitrogen through small holes in a sleeve of the first horizontal section into coal and rock mass for fracturing
Data Source
AI summary
A multi-level cross-district surface well pattern deployment method is provided. Firstly, a horizontal well is drilled from a location on a land surface corresponding to a junction H1 of a district rise coal pillar of the first district C1 in a first level and an upper mine field boundary coal pillar. A multilateral well is drilled from a location on the land surface corresponding to a junction H3 of a level coal pillar between the first and second levels, and the district rise coal pillar of the first district C1 in the first level. Liquid nitrogen is injected for permeability improvement after a gas drainage quantity decreases to 20% of an initial quantity. Gas drainage is repeated multiple times until the drainage quantity of coal bed methane through a gas drainage pipe of the horizontal pipe is reached 3 m3/min.