Simulating the Effects of Porosity and Permeability Variations to Optimize Coal Bed Methane Production

Coal bed methane (CBM) has become one of the most important future energy source in the world, along with other types of unconventional reservoirs such as shale gas and tight reservoirs. It is because of such discoveries that academic, oil and gas industry experts have started conducting studies and developing technologies to maximize recovery of methane adsorbed in coal.
Coal formations have low porosity and permeability, therefore, it is necessary to conduct studies to understand how to optimize natural gas recovery from coal. This project focuses on the effects of porosity and permeability with respect to production. Hydraulic fracturing stimulation technique is used in this paper to stimulate both the porosity and permeability of coal seam by injecting water into the formation. Thereafter, sensitivity analysis is conducted to study the effect of changing these two production control parameters to achieve CBM production optimization. The analysis are conducted based on hydraulic fracture models for coal seams, and to analyze the effects of porosity and permeability changes, Eclipse E300 is used. This research focuses on data from three distinct coal basins for analysis: Powder River, San Juan and Sarawak basins.
The results obtained indicate that coal formations are stimulated by injecting water into the formation at high rate and pressure. Results also show that by increasing permeability and porosity of coal, the production rate of natural gas is optimized.