The traditional concept of coalbed methane production is one where the coal natural fracture system is initially 100% saturated with water and that this water must be produced to initiate gas production. This paper summarizes an investigation designed to reconcile measured relative permeability data with well test analysis results obtained during single-phase and multi-phase tests, and with reservoir simulation projections of gas and water deliverability as a function of bottom-hole pressure. Improved well test and relative permeability measurement procedures are summarized so that projections of future fluid deliverability made during the dewatering and early multi-phase production stages are more accurate.

A variety of well tests were performed that included water slug tests, water injection tests, gas injection tests, and multi-phase production and shut-in tests. Estimates of absolute permeability obtained from these data were variable depending upon the test procedures. In addition, multi-phase and gas injection test analyses were strongly influenced by the relative permeability data used during the analysis. Based upon newly measured relative permeability data and by history matching multi-phase production data, it was possible to reconcile some of the differences in estimates of absolute permeability that were obtained from each of the test types. Finally, a new field procedure is proposed and demonstrated to measure permeability in wells producing both water and gas.

You can access this article if you purchase or spend a download.