Publications

A study conducted by PT Caltex Pacific Indonesia and Advanced Resources International, Inc. evaluated the coalbed methane (CBM) potential of Indonesia, the first rigorous study of this emerging natural gas resource. Well and seismic data provided by Pertamina and the Directorate of Coal showed CBM potential in a number of onshore Indonesian basins. CBM has been overlooked in Indonesia because (a) Coal rank is low (sub-bituminous) at surface outcrop, and (b) Nearly all coal mining takes place near the surface, where CBM gas content is negligible. However, our analysis indicates that geologic conditions at CBM completion depths (1,000 to 4,000 ft) are much more favorable. Well log and seismic data define thick, flat-lying, laterally continuous coal units in broad structural troughs, often associated with strong gas kicks. Coal rank increases from lignite at the surface to more prospective bituminous rank at target depth. CO2 content is low.Since 1985, over 20 Tcf of CBM reserves have been booked in the USA. CBM currently accounts for 7% of total U.S. gas production. Exploration focus has shifted towards lower rank settings, such as the Powder River (Ro=0.3%) and Uinta (Ro=0.6%) basins. Indonesian coals are thicker, deeper and higher in rank compared with Powder River basin coal reservoirs and could be more productive. We estimate that Indonesia has 337 Tcf of potentially completable CBM resources in the South and Central Sumatra, Barito, Kutei and other coal basins. Based on USA experience, 10% of this resource - 30 Tcf - may occur in high-quality, gas-saturated, permeable “fairways, where development may be economic.However, CBM development costs will likely be higher in Indonesia than in the U.S., at least initially, and fiscal incentives may be required to jump-start this new gas supply source.