Operating Canadas Biggest CBM Field by Oil and Gas Inquirer, March 15, 2006
Just east of Calgary, EnCana Corporation operates Canada’s largest producing coalbed methane (CBM) field, and also one of the oldest. In stark contrast to the land contamination and lawsuits spawned in the Powder River Basin of Montana and Wyoming, EnCana’s five-year-old CBM project operates as smoothly – although not quite as quietly — as a Swiss watch. The Horseshoe Canyon coal zone in this area stretches from the foothills eastward to the Siksika Nation. The most permeable portion makes up EnCana’s Strathmore Sub Business Unit, which sits between Calgary and Highway 21. The Bow River forms its southern border, while the northern limit lies slightly beyond the village of Acme. The Strathmore unit currently includes 1,700 wells, with 400 more scheduled for drilling during 2006. About 75% of those wells tap CBM, a supply that is expected to last at least 40 years. Strathmore production at present totals 113 million cu. ft. per day of sweet, dry methane. Horseshoe Canyon coals supply an estimated 30% to 60%, and the remainder coming from underlying sands.
Kim Currie supervises this sprawling field operation. Raised on a dairy farm at Salmon Arm in the British Columbia interior, the EnCana veteran relates easily to the grain farmers, cattlemen and acreage residents who populate the neatly-tailored countryside of his district. … “Unless EnCana takes a joint user attitude to the land and gets along with its neighbours, we’d experience far more regulatory delays and other difficulties.” …
Well density is a big concern for many residents. EnCana drills as many as eight wells per section. That density is required to draw gas from the coal seams because wellhead pressure is so low – often less than the pressure needed to drive a house gas meter. At one well per section, draining a CBM formation could take two centuries. … The water table is a key concern of rural residents, who wonder if underground disturbance might not cause gas to migrate into their wells. EnCana tests local water wells before it drills, since gas can be present in shallow water naturally. … To protect the water table, the company’s gas wells do not produce from depths shallower than 175 metres. CBM in the Strathmore field generally comes from 250-650 metres.