The Effects of Gas Injection on Coalbed Methane Production. A Simulation

In optimizing the production of coalbed methane, several methods could be
taken to increase the recovery process. One of the methods is by injecting gas with
competitive adsorption capability compared to methane. Injection of gases such as
carbon dioxide and nitrogen is currently a common practice in unconventional oil
and gas industry. Apparently, research on the coalbed methane is numerous and
actively done in countries with potential coalbed prospect. Historic wells data such as
in American basin are very useful as they provide reliable information and variables
for further research. Moreover, by conducting investigation on such wells, the
understanding of how the gas injection affects the recovery process could be attained.
In this research, the focus will be pointed on the usage of nitrogen and carbon
dioxide as the injecting gases in San Juan basin production units through
computerized simulation. This paper will also outlines comparative evaluation
between nitrogen and carbon dioxide injection in coalbed reservoir in order to assess
different outcomes from each type of gas injections respectively. In laboratory,
experiments have managed to practically prove the different effects posed by both
gas injections on coal matrix in terms such as the gas breakthrough time, the partial
permeability trend, the displacement effectiveness and gas flooding polarity.
However, it is fair to state that simulation is useful tool to estimate and predict the
production trend using the real data obtained from laboratory experiments. Hence, it
is expected that more information could be interpreted from this research simulation
study thus bring out valuable findings to help in forming more solid inferences to
what might have not been understood yet in coalbed study.
Key words – coalbed methane, enhanced coalbed methane recovery, gas injections,
San Juan Basin.