Methane Emission during Gas and Rock Outburst on the Basis of the Unipore Model

Abstract

The goal of this paper is to analyze the phenomenon of gas emission during a methane and coal outburst based on the unipore Crank diffusion model for spherical grains and plane sheets. Two occurrences in the Upper Silesian Coal Basin were analyzed: an outburst in a Zofiówka coal mine in 2005 and an outburst in a Budryk coal mine in 2012. Those two outbursts differed considerably. The first one was connected with an unidentified tectonic disturbance in the form of a triple, interlocking fault, and the other one is an example of an outburst in an area free from tectonic disturbances. The model analysis required laboratory tests in order to determine the sorption properties of coals from post-outburst masses. Sorption isotherms and the values of the effective diffusion coefficient were specified. The post-outburst masses were subjected to sieve analysis and the grain composition curves were plotted. The researchers also used the measurement data provided by proper mine services, such as the methane content, the volume of post-outburst masses, and the time courses of CH4 concentration changes in excavations. They were recorded by methane measurement systems in the mines.

Expansionary Evolution Characteristics of Plastic Zone in Rock and Coal Mass Ahead of Excavation Face and the Mechanism of Coal and Gas Outburst

“…Zou et al [8] established a production deployment evaluation system using a Bayesian network with 11 indices for outburst-prone coal mines based on summaries of experts and production experience of coal mines in Chongqing, China. Based on the Unipore Crank Diffusion Model for spherical grains and plane sheets, Norbert et al [9] analyzed the phenomenon of gas emission during a coal and gas outburst. Using a statistical method, Nilufer et al [10] employed Structural Equation Modeling (SEM) to identify the relationship between the parameters (mining depth, coal seam gas content, and moisture content) and contributing factors (seam thickness, seam inclination, and distance from fault) affecting the coal and gas outbursts for an underground coal mine in Turkey and to analyze multiple interactions among them.…”

Biogeochemical Controls on Methane Generation: A Review on Indian Coal Resources

“…However, they emphasized that diffusion is the predominant transport process within coals, owing to their ultra-microporous characteristics, as coal contains a dominant pore distribution of <1 nm, leading to abundant empty spaces [30]. Additionally, Norbert et al [50], in the study of coal sorption analyses around gas outburst zones, upheld the idea that the diffusion process is the dominant factor in the coal gas transport mechanism. Moreover, in methane emission studies, Wierzbicki et al [51] asserted that the diffusion model is the governing aspect of methane emission from coal.…”

Comparative Analysis of the Drainage Effect Based on Improved Hydraulic Flushing Technology

“…With the gradual deep mining of coal mines in China, coal seams are increasingly characterized by high stress, high gas content, and high pressure. Such many unfavorable features of coalbed methane occurrence conditions restrict the efficient exploitation of coalbed methane resources in China, − which also bring the risk of coal and gas outburst accidents, especially in a soft coal stratified development area. − …”