SOUVENIR COMMITTEE - Birbal Sahni Institute of Palaeobotany

Training Programme on “PALYNOLOGY IN FOSSIL FUEL EXPLORATION”
[ September 10-17, 2012 ]
GEOLOGICAL FACETS OF COAL BED METHANE
ATUL KUMAR VARMA
Department of Applied Geology, Indian School of Mines, Dhanbad- 826004
E-mail: atulvarma@hotmail.com
Author discusses various geological parameters for coal bed methane (CBM) exploration. The
nanopores (micropores) are very significant for CBM as well as capture and storage of carbon dioxide
(CO2) in coal seams reducing the release of greenhouse gas to the atmosphere. The coal plays an
important resource in the production of methane from coalbeds. The nanopores (micropores) are
responsible for most of the porosity in coal whereas the cleats provide the principal source of
permeability for fluid flow. Coal beds have several types of cleats viz. (a) face cleat (primary cleat) (b)
butt cleat (secondary cleat) (c) tertiary cleat (d) master cleat (e) super cleat (f) micro-cleat Methane flow
in coal bed indicates that methane in gaseous phase must diffuse through the nanopore structure of coal
matrix until reaches a cleat followed by Darcy flow through the cleats to a well. Cleat attributes include
size, spacing, connectivity, aperture, degree of mineral fill, and patterns of preferred orientation on local
and regional scales (Mavor and Close,1991; Karacan and Okandan, 2000). The relation between gas flow
behavior and coal seam structure is generally modeled as a dual porosity system of macropores (cleats)
and surrounding system of micropores (nanopores).The diffusion is generally modeled applying Fick’s
Law and the free flow is modeled using Darcy’s Law. It is also interpreted regarding nanopore
development and evolution in coal which takes place in three distinct stages. Here, author also discusses
about coal and its petrographic composition.
Birbal Sahni Institute of Palaeobotany, Lucknow
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