Coalbed methane reservoir (CBM) performance is controlled by a complex set of
reservoir, geologic, completion and operational parameters and the inter-relationships
between those parameters. Therefore in order to understand and analyze CBM prospects,
it is necessary to understand the following; (1) the relative importance of each parameter,
(2) how they change under different constraints, and (3) what they mean as input
parameters to the simulator. CBM exhibits a number of obvious differences from
conventional gas reservoirs, one of which is in its modeling.
This thesis includes a sensitivity study that provides a fuller understanding of the
parameters involved in coalbed methane production, how coalbed methane reservoirs are
modeled and the effects of the various modeling parameters on its reservoir performance.
A dual porosity coalbed methane simulator is used to model primary production from a
single well coal seam, for a variety of coal properties for this work. Varying different
coal properties such as desorption time ( ÃÂ), initial gas adsorbed (Vi), fracture and matrix
permabilities (kf and km), fracture and matrix porosity ( ÃÂf
and ÃÂm), initial fracture and
matrix pressure (to enable modeling of saturated and undersaturated reservoirs), we have
approximated different types of coals. As part of the work, I will also investigate the modeling parameters that affect the dual
peaking behavior observed during production from coalbed methane reservoirs.
Generalized correlations, for a 2-D dimensional single well model are developed. The
predictive equations can be used to predict the magnitude and time of peak gas rate
