Gas field a joule in crown of Darling Downs | The Courier-Mail

DRILLING rigs are working 24 hours a day to find and capture huge deposits of coal seam gas on the Darling Downs in the biggest flurry of exploration and mining southeast Queensland has seen.





West of Dalby the landscape of cotton and sorghum paddocks and fields of grazing cattle are dotted with drilling rigs, pilot wells and new gas processing plants that began coming on line this year.

The gas reserves lie in the vast coal deposits up to 1000m underground in the Surat Basin stretching more than 500km from Taroom in Queensland to Gilgandra in NSW.

At present consumption rates, the reserves of 2627 petajoules so far discovered in just the past five years in the district could supply Queensland's current gas needs for 30 years.

However, total reserves in the district are estimated at 15,000PJ.

One of the fields, at Tipton West, 30km south of Dalby, is one of the largest onshore coal seam gas fields with reserves of up to 2000PJ.

Coal seam gas production in Queensland has risen dramatically from 2PJ in 1998, or about 3 per cent of the state's gas market, to 30PJ a year now, making up a third of the state's total gas production.

Two-thirds of the CSG-rich Surat Basin lies under southern inland Queensland, and the basin covering a total area of 270,000sq km is laced with coal seams from just below the surface to deep underground.

Coal seam gas has been found in the lower coal seams from 200m to 550m below the surface where it is trapped in coal deposits by water pressure and has lain untapped and unexplored until five years ago, when the technology was developed to safely capture the flammable gas.

Once wells are drilled, water is pumped or free-flows to the surface, releasing pressure on the gas, which is about 96 per cent methane, and allowing it to escape to the surface.

Exploration has been restricted to areas close to the Roma-to-Brisbane gas pipeline thus far but even so, the vast reserves discovered are six times larger than the natural gas reserves in the Cooper Basin and Bowen Basin combined.

Department of Natural Resources, Mines and Water geoscience manager for coal and petroleum John Draper said the amount of coal seam gas would far exceed the total natural gas reserves discovered in Queensland.

Of the state's combined natural gas and coal seam gas reserves of 180,000 million cubic metres, one-sixth is natural gas and five-sixths, or 150,000 million cu m, is coal seam gas, he said.

Although the Surat Basin coal seam gas reserves discovered so far are smaller and of lower quality than those found in the Bowen Basin further north, the Darling Downs fields are a vast resource at shallower depths and are therefore cheaper to mine.

The resource is also much closer to Brisbane, the main market, which makes it viable to value-add by using the gas to generate electricity.

Increased exploration for coal seam gas was spurred by the State Government's Cleaner Energy Strategy in 2002 requiring 13 per cent of Queensland's electricity to be generated from gas by 2005.

Twenty pilot gas wells drilled at Tipton West have revealed one of the largest onshore gas resources in Australia, only 200m below the surface.

Arrow Energy's field has the potential to produce up to 2000PJ of coal seam gas and 75 production wells are now being drilled.

The gas field is being developed in three stages, with $35 million being invested to develop stage one to produce 10PJ of gas a year from early next year.

Arrow Energy has also discovered large coal seam gas reserves at its Kogan North gas field, 40km west of Dalby and was the first company to deliver gas from the Surat Basin to customers in January this year.

Five pilot wells drilled two years ago are yielding 550 million cu ft of gas a day and reserves of up to 157PJ have been found on the field.

Drilling of 31 production wells has been completed and gas and water pipelines will network the wells to supply a new gas processing plant that will feed into the Roma to Brisbane pipeline.

Queensland Gas Company is a major player in the Surat Basin gas fields, securing funding for the first coal seam gas project in Australia to drill pilot wells at Berwyndale South gas field, 80km northwest of Dalby.

Exploration at Berwyndale and the nearby Argyle gas fields 10km south, have secured reserves of up to 2464PJ, equivalent to 2.4 trillion cu ft of coal seam gas.

Berwyndale production wells are due to deliver their first gas to customers next month with Argyle due to come on line next year.

The $53 million pilot drilling program, sinking of 25 production wells and construction of a gas processing plant, is almost complete with gas due to begin flowing from June this year.

Site superintendent Ken Rixon said four of the wells were free-flowing, with both water and gas flowing from the well without the need to pump the water, reducing long-term operation costs.

Ninety workers are currently on site, working on drill rigs, laying gas and water pipes, building the gas processing plant and building dams to capture water from the gas wells.

ERM Group is building a $340 million gas-fired power station at Braemar 20km west of Kogan that is due for completion this year.

Three 150 megawatt gas turbines are on site at the power station being built by Alstom.

Development is also forging ahead in the coal and power generation sectors with open-cut coal mining booming and Australia's largest single power generating plant being built at Kogan Creek, 4km from a new coal mine, 40km northwest of Dalby, near Kogan.

Almost 700 workers are currently on site building the major components of the power station that is due for completion in August next year.

Only 10km southeast of Kogan Creek power station is another coal mine, Peabody's open-cut Wilkie Creek mine where production is being stepped up from 1.3 million tonnes last year to 1.9 million tonnes this year due to growing global demand.

General manager and site senior executive Blair Jackson says production will be increased again next year to 2.3 million tonnes.