Advanced Technology of Drilling and Hydraulic Loosening in Coal Bed Methane Using a Cavitation Hydrovibrator – Experience and Prospects

Abstract

Modern progressive technologies use static fluid injection into seams for safe and cost-effective operation of coal seams. However, the deterioration of mining and geological conditions leads to a significant decrease in the efficiency of the process of methane sequestration from coal seams in case of increase in the depth of development of gas-bearing coal seams. This deterioration is due to a change in the stress-strain state of deep rock massifs, their low permeability, strong anisotropy of soft coal, leading to an increase in dynamic manifestations of rock pressure in the form of sudden outbursts of coal and gas, and rock destructions with catastrophic consequences. An advanced technology for hydraulic loosening and recovery of methane from gas-bearing coal seams, based on the creation of hydrodynamic impulses in a well surface and their transformation into mechanical vibration loading to coal seam, was developed. Such impact to the coal mass leads to the development of a system of cracks. As a result, the efficiency of coalbed hydraulic loosening increases, the zones of moistening and unloading of the formation increase, the gas emission of methane is intensified, the level of dust formation and the resistance of coal to cutting during its destruction are reduced.