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A methodology for determining gob permeability distributions and its application to reservoir modeling of coal mine longwalls.

Authors

Esterhuizen-GS; Karacan-C

Source

2007 SME Annual Meeting and Exhibit, February 25-28, Denver Colorado, Preprint 07-078. Littleton, CO: Society for Mining, Metallurgy, and Exploration, Inc., 2007 Feb; :1-6

Link

http://www.smenet.org/page/index.cfm?title=SME_Annual_Meeting_Information&CFID=3275081&CFTOKEN=12949495 

NIOSHTIC No.

20031652 

Abstract

Methane can be a significant hazard in coal mine longwalling operations and extensive methane mitigation techniques are employed by coal mine operators. Reservoir modeling techniques are used to better understand the liberation and migration of methane from the surrounding rocks towards the mine ventilation system. The caved rock behind the advancing longwall face, known as the gob, can contain high void ratios, providing high permeability flow paths to the methane. The gob is progressively compacted by the weight of the overburden, resulting in a reduction in the void ratio and associated permeability. Estimating the permeability distribution within the gob poses challenges due to its complexity. The authors have developed a new methodology to determine both horizontal and vertical variations in the permeability of the gob. Variations of the permeability in the vertical direction are based on a model of caving and block rotation, which considers the effect of block dimensions and fall height on the void ratio. Gob compaction by the overburden and associated permeability changes are determined from a three-dimensional geo-mechanical model which simulates the gob as a strain hardening granular material. The resulting three-dimensional permeability distribution in the gob is then transferred to a reservoir model. The paper demonstrates the application of the method and shows that reasonable results are obtained when compared to empirical experience and measurements.

Keywords

Mining-industry; Underground-mining; Safety-research; Coal-mining; Longwall-mining; Models; Computer-models; Methanes

Contact

NIOSH Pittsburgh Research Laboratory, P.O. Box 18070, Pittsburgh, PA 15236

CAS No.

74-82-8

Publication Date

20070225

Document Type

Conference/Symposia Proceedings

Fiscal Year

2007

NTIS Accession No.

NTIS Price

NIOSH Division

PRL

Source Name

2007 SME Annual Meeting and Exhibit, February 25-28, Denver Colorado, Preprint 07-078

State

PA; CO