Simulating the Effect of the Coal Density on Methane Recovery for CBM Study

Unconventional coal bed methane (CBM) reservoirs have a huge future potential to production but difficult to develop due to their complexity. Analyzing production performance and estimating original gas in place somewhat complicated and has led to numerous methods of approximating production performance. Hydrocarbon reservoirs are known to react to changes in their properties, particularly coal density. Therefore, it is important to study the effect of coal density changes towards production and gas in place of CBM. The production rates of four CBM fields which are Qinshui Basin, San Juan Basin, and Western Canada Basin will be simulated and analyzed, with coal density being the manipulated variable. Simulation will be performed using the ECLIPSE E300 model, with several assumptions made. From the result, it is clear to see that coal density enhances the production of methane gas from CBM fields. An increase in coal density leads to higher production rates and a prolonged maximum production time as well as gas in place. High reservoir pressure, Langmuir isotherms, gas content and coal density are favorable for CBM production.