Permeability of Coking Coals and Patterns of Its Change in Leninsky Area, Kuznetsk Coal Basin, Russia

Tatiana Shilova,Sergey Serdyukov

doi:10.3390/app11093969

Abstract

A prediction of the permeability of gas-bearing coking coals in the Leninsky area, Kuznetsk coal basin (Kuzbass), which is promising for the production of coal methane, was performed. The results of laboratory studies of coal permeability and cleat compressibility under hydrostatic stress conditions are presented. As the confining pressure increased by 8 times (from 1 MPa to 8 MPa), the coal permeability perpendicular to the butt cleat direction decreased by 6.7 times (from 60 mD to 9 mD). The coal cleat compressibility was 0.085 MPa−1. On the basis of the results of filtration tests and microstructural analysis of the coking coals, we provide the estimation of the permeability anisotropy along the bedding planes (perpendicular to the face and butt cleat directions). The predicted dependences of gas-bearing coking coal permeability perpendicular to the butt and face cleat directions on depth and on features of coal seam bedding were determined under uniaxial strain conditions. It was found that in the coking coal depth intervals, as the depth increased, their permeability decreased by 61–82%. The obtained results can be used to select facilities and to design industrial works for the extraction of coal methane in the region.

Highlights

The recent intensification of mining and usage of coal resources is associated with an increase in mining depths
As the confining hydrostatic pressure increased by 8 times, the coal permeability decreased by 6.7 times (Figure 5)
For a stress regime described by uniaxial strain and mean stress, the predicted coal permeability ratios were determined from Equations (9) and (10)

Summary

Introduction

The recent intensification of mining and usage of coal resources is associated with an increase in mining depths. The gas content increases with depth, while the rock permeability decreases. These features can produce dynamic disasters, such as gas outbursts and explosions, and stop mining operations in underground mines [1,2,3]. Gas drainage of coal seams is an essential technique that is used both to prevent gas dynamic disasters in mines and to produce CBM for later utilization. Coal permeability should be considered in gas drainage design and performance assessment, as it is an important parameter that affects gas filtration in rocks and CBM production [1,4,5,6,7]. Modeling coal seam permeability is necessary to design gas drainage systems and to optimally extract CBM to the surface via wells [8]

Methods

Results

Discussion

Conclusion