Full-life-cycle efficient extraction method for coal-series gas in low-permeability reservoir

Abstract

The invention provides a full-life-cycle efficient extraction method for low-permeability reservoir coal series gas, and belongs to the technical field of low-permeability reservoir coal series gas extraction. The problem that the full-life-cycle extraction efficiency of the low-permeability reservoir coal series gas is low is solved; the method comprises the following steps of: establishing a reservoir geomechanical model by taking a low-permeability coal series reservoir which is developed in a vertical overlapping manner as an object, obtaining reservoir lithology, designing a coal seam mining process, analyzing an overlying strata deformation-damage-seepage spatio-temporal evolution law caused by coal seam mining, and arranging a special extraction working roadway for coal series gas at the top of a mining coal seam through comparison and optimization, a key layer fracturing process is designed, a key layer is actively broken, pressure relief disturbance on a coal series reservoir is formed together with coal seam mining, a nitrogen foam fracturing technology is combined, drill site and drill hole arrangement characteristics are designed, efficient rock breaking and permeability increasing of a multi-layer coal series gas-containing rock mass of the coal series reservoir are achieved, and on this basis, a coal series gas flow field evolution model is established; a dynamic efficient extraction method is designed; the method is applied to low-permeability reservoir coal gas extraction.

Description

technical field [0001] The invention belongs to the technical field of development and utilization of low-permeability coal measure reservoirs, and relates to adopting low-level coal seam mining to relieve pressure disturbance, high-level key layers to actively fracturing, using nitrogen foam fracturing to form a multi-reservoir fracture network, and constructing a full life cycle intelligent linkage The extraction system realizes the efficient extraction of coal measure gas from low permeability coal reservoirs. Background technique [0002] Coal-measure gas is mainly composed of coal-measure endogenous and internal storage humic gas, including coal-bed methane, coal-measure sandstone gas, shale gas and coal-measure carbonate gas, etc. It is an important component of my country's natural gas energy structure. The efficient extraction of gas is of great significance for promoting the adjustment of my country's energy structure and the energy revolution in Shanxi Province. It...

AI Technical Summary

Problems solved by technology

At present, although the top drainage roadway or high-level drainage roadway can be used to realize high gas release and drainage in the mining face and reduce the gas concentration, it cannot effectively drain other coal in the shale layer or sandstone layer in the roof of the coal seam. Qi

In addition, there are still many deficiencies in the current gas drainage roadway, such as: 1) The roadway will be damaged with the mining of the working face, and it only serves for the extraction of coalbed methane during the mining process, but cannot effectively drain the coalbed methane after the mining of the working face. Coal-measure gas enriched in goafs and fractured areas; 2) The drainage effect of the roadway is affected by the development of cracks in the overburden of the working face, and the drainage effect is poor when the cracks are not developed; 3) The drainage control of the roadway is mostly based on human experience , usually resulting in low gas production rate, low extraction efficiency, etc.

Images