Resource recovery and cavity growth during the Rocky Mountain 1 field test

Resource recovery and cavity growth remain important issues affecting performance, scale-up and overall process efficiency for underground coal gasification (UCG). Results from the recently completed dual-module Rocky Mountain I (RM I) UCG experiment give us firsthand information concerning these important parameters. During the RM I test, two gasifiers, the Controlled Retracting Injection Point (CRIP) and the Extended Linked Well (ELW) modules, were operated simultaneously. These modules differed in well completion geometry and to a lesser extent in operating strategy. Using material balance, thermowell and tracer gas information, cavity development, gas production rates and yields, and general features of the two modules are discussed and compared. Also, the linking phase of the test is described, and effects of process parameter changes on system performance are discussed. The major conclusion obtained from data analysis is the importance of maintaining oxidant injection low in the coal seam at all times. Performance of the CRIP gasifier, for which the above condition was met, is shown to compare very favorably with performance of surface gasifiers. 10 refs., 15 figs., 3 tabs.