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Mining Publication: Analysis of Gob Gas Venthole Production Performances for Strata Gas Control in Longwall Mining
Keywords: Gob gas vent holes Gobs
Original creation date: March 2018
Authors: CO Karacan
Peer Reviewed Journal Article - March 2018
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NIOSHTIC2 Number: 20046669
Int J Rock Mech Min Sci 2015 Oct; 79:9-18
Longwall mining of coal seams affects a large area of overburden by deforming it and creating stress-relief fractures, as well as bedding plane separations, as the mining face progresses. Stress-relief fractures and bedding plane separations are recognized as major pathways for gas migration from gas-bearing strata into sealed and active areas of the mines. In order for strata gas not to enter and inundate the ventilation system of a mine, gob gas ventholes (GGVs) can be used as a methane control measure. The aim of this paper is to analyze production performances of GGVs drilled over a longwall panel. These boreholes were drilled to control methane emissions from the Pratt group of coals due to stress-relief fracturing and bedding plane separations into a longwall mine operating in the Mary Lee/Blue Creek coal seam of the Upper Pottsville Formation in the Black Warrior Basin, Alabama. During the course of the study, Pratt coal's reservoir properties were integrated with production data of the GGVs. These data were analyzed by using material balance techniques to estimate radius of influence of GGVs, gas-in-place and coal pressures, as well as their variations during mining.The results show that the GGVs drilled to extract gas from the stress-relief zone of the Pratt coal interval is highly effective in removing gas from the Upper Pottsville Formation. The radii of influence of the GGVs were in the order of 330-380. m, exceeding the widths of the panels, due to bedding plane separations and stress relieved by fracturing. Material balance analyses indicated that the initial pressure of the Pratt coals, which was around 648. KPa when longwall mining started, decreased to approximately 150. KPa as the result of strata fracturing and production of released gas. Approximately 70% of the initial gas-in-place within the area of influence of the GGVs was captured during a period of one year.
Cover image for Analysis of Gob Gas Venthole Production Performances for Strata Gas Control in Longwall MiningPeer Reviewed Journal Article - March 2018
Go to Web Page
NIOSHTIC2 Number: 20046669
Int J Rock Mech Min Sci 2015 Oct; 79:9-18
See Also
Computational Fluid Dynamics Modeling of Spontaneous Heating in Longwall Gob Areas
Control of Longwall Gob Gas With Cross-Measure Boreholes (Upper Kittanning Coalbed)
Development of Multiple Regression Functions for Performance Prediction of Gob Gas Ventholes for Sealed and Active Longwall Mines
Effect of a Surface Borehole on Longwall Gob Degasification (Pocahontas No. 3 Coalbed)
Effect of Longwall Face Advance on Spontaneous Heating in Longwall Gob Areas
Longwall Gob Degasification With Surface Ventilation Boreholes Above the Lower Kittanning Coalbed
Probabilistic Modeling Using Bivariate Normal Distributions for Identification of Flow and Displacement Intervals in Longwall Overburden
Reservoir Diagnosis of Longwall Gobs Through Drawdown Tests and Decline Curve Analyses of Gob Gas Venthole Productions
Stochastic Modeling of Gob Gas Venthole Production Performances in Active and Completed Longwall Panels of Coal Mines
Technology News 489 - Reducing the Danger of Explosions in Sealed Areas (Gobs) in Mines
Page last reviewed: August 30, 2018
Page last updated: August 30, 2018
Content source: National Institute for Occupational Safety and Health, Mining Program
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