From left, CRL Energy technician Hayden MacKenzie, and environmental hydrologist Dave Trumm, with Nadia Ariana, Agus Budiluher from PT Geoservices. Behind is the drill rig used for the first CSG exploration hole in Borneo.

CRL Energy’s Geology Group in Christchurch have for the last six years been on the cutting edge of helping several New Zealand clients with coal seam gas (CSG) interests, however, in the last financial year, the service has expanded to assist clients in Australia, Vietnam and Indonesia.

Dr James Pope, Manager of the Geology Group, says CRL Energy’s expertise in the measurement and analysis of gas desorption (release of gas) data from freshly drilled coal samples, and their ability to reliably predict the gas production performance and reserve potential of coal seam gas reservoirs, has captured the attention of energy companies off shore.

“Among other contracts, our field geologists have this year teamed up with PT Geoservices, an Indonesian company, where they are supplying the logistics and field staff, and we are providing our expertise to oversee the work. Exploration for CSG in Indonesia is at grass roots stage and the potential is huge,” says Dr Pope.

CSG also called coal bed methane (CBM) or coal seam methane, is mostly methane in composition and is adsorbed to micropore surfaces within coal at near liquid methane density. This gas is extracted via wells which are drilled down into coal seams. The gas is released from the coal along natural fractures and cleats (desorbed) when pressure on the coal seam is reduced, usually by removal of water from the seam.

Various techniques can be used to enhance the rate of desorbtion. Mostly these relate to enhancing gas flow into the well through under-reaming or hydrofracturing the coal. Trials are currently being conducted on pumping of carbon dioxide into the reservoir to increase field pressure and increase the flow of methane (enhanced coal seam gas - ECSG or ECBM). This technology, if successful, provides a double bonus as the CO2 is sequestered and the methane released.