Study on the Pseudo-Slope Length Effect of Buried Pipe Extraction in Fully Mechanized Caving Area on Gas Migration Law in Goaf

Abstract

To study the law of gas transportation in mining areas, Fluent numerical simulation software was applied to examine the influence of different pseudo-slope lengths (PSL) on gas concentration in a U-ventilated working area under no-extraction conditions. Based on this, numerical simulation experiments were conducted on the buried pipe extraction arrangement parameters. The simulation found that when there was no extraction, the PSL had an impact on the airflow in the extraction area, which caused the airflow in the extraction area to be disordered, causing gas to accumulate locally at the working area. When the buried pipe depths (BPDs) and PSLs of the working area worked together, the gas concentration of the working area was lower when the inlet air influence zone and the extraction influence zone were through; otherwise, gas concentration accumulation occurred at the working area. The research results showed that when the PSL was at 25 m and BPD was at 20 m, the gas concentration at the working area was not abnormal, and the gas concentration in the upper corner was lower. By adjusting the PSL and BPD of the test working area, the maximum gas concentration in the upper corner was reduced to 0.46% and the maximum gas concentration in the return air outlet was reduced to 0.41%. The experimental and practical results provide important reference values for coal and gas co-mining.

Substantiation of Drilling Parameters for Undermined Drainage Boreholes for Increasing Methane Production from Unconventional Coal-Gas Collectors

“…The next important aspect is obtaining a theoretical model [75][76][77] (process formulas, or a regression having a preset level of "goodness-of-fit"), which is still an open fundamental scientific task for three-dimensional models (see, for example, [78][79][80]). At this stage, the author's approach provides for the construction of a model of the response surface most qualitatively (based on the Q-Q curve) reflecting the general regularities of in situ data.…”

Technogenic Reservoirs Resources of Mine Methane When Implementing the Circular Waste Management Concept

“…This allows consideration of the process under study as a (prescribed implicitly) CH 4 function of S (the space axis being a distance from the beginning of the site "by the analogy with the distance from the beginning of the site to the longwall position at other times")-t (measurement time). The next important aspect remaining is to obtain a theoretical model [48,49] (a process formula or regression having a specified goodness-of-fit" level), which is still an open fundamental scientific problem in the case of three-dimensional models (see, for instance, [50,51]).…”