Method for pumping coal bed gas from long-distance pressure-relieved coal bed

Abstract

The invention relates to a method for pumping coal bed gas from a long-distance pressure-relieved coal bed. When extraction is performed in the long-distance pressure-relieved coal bed, the coal bed achieves the critical desorption state, a large amount of free gas exists, and free methane also exists in other nearby rock layers, thereby causing huge potential safety hazard; if the long-distance pressure-relieved coal bed is very soft, the conditions of pumping along the coal bed are not satisfied, the problem can only be solved by only adopting a rock lane and crossing boreholes, however, the cost in this way is very high, the engineering amount is large, and the safe and high-efficient production of a coal mine is greatly affected. Before the extraction of the lower coal bed, the appropriate rock layer is selected nearby the long-distance pressure-relieved coal bed, the construction level comprises the multiple branch long boreholes, a large number of non-communicating cracks are penetrated, and the branch boreholes extend into the coal bed, thereby achieving the purposes of intercepting pressure-relieved gas and pumping the coal bed gas. The cost is lower, and the engineering amount is greatly reduced, thereby being an advanced technology integrating the safe and high-efficient production of the coal mine and high-efficient development of energy into a whole.

Description

technical field [0001] The invention relates to coalbed methane (gas) safety management and development technology, in particular to a method for extracting methane released from long-distance pressure-relieving coal seams by using underground high-level cross-branch horizontal long boreholes. technical background [0002] In the process of coal mining, with the output of coal, the overlying strata overlying the mining coal seam lose the support of the coal seam and begin to collapse and deform in an increasing range, gradually forming caving zones, water-conducting crack zones and curved In the subsidence zone, it is generally believed that the rock formations in the caving zone and the water-conducting fracture zone form an interconnected system, and the methane migrated into it is easy to extract, while for the lower part of the curved subsidence zone, there may be a large number of disconnected fractures, However, these fractures may be connected to adjacent coal seams. ...

AI Technical Summary

Problems solved by technology

When the long-distance pressure relief coal seam is recovered, on the one hand, the coal seam itself reaches a critical desorption state, and there is a large amount of free gas, and the free methane in other adjacent rock formations will cause a huge safety hazard. If the long-distance pressure relief co