US scientist backs gas projects

JAMES NASON
02 Oct, 2010 04:00 AM

A US soil scientist and wastewater irrigation expert with experience in the US coal seam gas industry believes Queens-land landholders may gain from the emerging coal seam gas industry in the Surat Basin.

John Zupancic is a partner in the US company BeneTerra, which works as a water management intermediary between coalbed methane producers and land-owners in Wyoming’s Powder River Basin.

BeneTerra contracts with energy companies to handle water from their wells and then designs and manages re-use systems which filter, treat and pump the water to subsurface drip irrigation networks on surrounding farms.

The process provides energy companies with a year-round water dispersal solution and gives landowners in semi-arid environments year-round access to free or low-cost water to grow hay and forage crops.

About 20 percent of all coalbed methane water produced in the Powder River Basin is beneficially reused, which results in 20-24 gigalitres (20,000-24,000 megalitres) delivered to local landowners for subsurface and sprinkler irrigation, stock water and aquifer recharge every year. Most produced water in the Powder River Basin still goes into infiltration/evaporation dams.

Mr Zupancic is currently overseeing a joint project between BeneTerra and Wood Group Wagners in Queensland to assess whether similar strategies can be applied in the Surat Basin.

The sandstone layers and hydrology of the Powder River Basin and Great Artesian Basin were very similar, Mr Zupancic said. But there were differences in soil type. Where calcareous loams predominated in the Powder River Basin, higher clay content soils were more common in the Surat Basin, and their susceptibility to damage from exposure to sodium presented a key challenge in re-using CSG water here.

The CSG industry is relatively new in Queensland, but has been operating for more than 20 years in the US.

A key point Mr Zupancic wished to emphasise was that much of the water produced from coal seams was of poor quality and was never likely to be put to beneficial use for purposes such as crop irrigation, aquifer recharge, stock watering or stream augmentation if the CSG industry did not exist to produce it.

The advent of the CSG industry presented a rare opportunity to use the coal seam water resource by allowing it to be desalinated for beneficial purposes.

“Without the revenues generated from gas sales this water would remain virtually useless for perpetuity,” Mr Zupancic said. He said Queensland landholders could further benefit from the CSG industry with improved roads, new gates and cattle grids, jobs for their children and cash payments for access.

Mr Zupancic said Queensland’s emerging CSG industry was being subjected to far stronger regulatory controls than those in the US in the 1980s and 1990s, when the coalbed methane industry was first developing.

He said he attended the State Government’s recent community consultation forum in Chinchilla and was impressed by what he saw.

“The level of thought that has gone into regulating the industry here is far greater than it ever was when we started the Coal Seam Gas industry in the Powder River Basin,” Mr Zupancic said.

“The level and the degree of consideration for all aspects from code of conduct and land access to make good provisions for water, those are pretty well thought out. In the US a lot of that was sorted out in the courtroom.”

He said that while there had been some negative impacts early in the industry’s development, the industry had come a long way in 20 years and the many landholders and energy companies that BeneTerra worked with today shared a harmonious and mutually beneficial relationship.

“We have 24,000 functioning wells in the Powder River Basin right now, and we have had very few problems where people have lost water supplies,” Mr Zupancic said. Where aquifer drain-age issues occurred in the Powder River Basin, make-good provisions had been effective at dealing with them, he said.

“There is one case with a lawsuit. I think the company was unjustly accused of draining down a very thin shallow coal aquifer that some people were using for drinking water, and in this case the energy company hauled water to this small community of about six homes. And then they brought well water from a nearby aquifer and set up the pipes and the pumps and so forth to supply them with a water system.

“I know of some cases where the energy company went in and drilled a new bore and that seemed to work. I don’t know of any cases in the Powder River Basin where there is an unresolved issue over drainage.”

However he added there were no easy answers where slow vertical flow rates meant a time-lag between extraction activities and declines in upper aquifers, a problem identified in a study of the Condamine Alluvium and Walloon Coal Measures by hydro-geologist John Hillier.

“There is one issue that Hillier brings up – that drainage of the sandstone occurs long after the drainage of the coal. I don’t have an answer for that. But I would hope that more study will go into that issue and that concern and an answer will be derived.”

The Queensland Government has nominated reinjection of coal seam gas water into underground structures as a preferred method for CSG water.

About 5pc of all coalbed methane water produced in the Powder River Basin was re-injected. While it did work in places, results had been mixed.

“It is not a highly used option because we have been able to irrigate with a lot of it and because of a lot of the higher quality water is put into streams over there. But people have been successful at injection, and there have been some failures.”

“My drilling friends tell me it is probably more difficulty to predict which aquifers will take water than it is to predict how much we can extract.

“One of the problems is that there are fine particulates and clays that come out of the coal seam and if you pump those back into the aquifer you plug them up, you plug up the sandstone or the coal seam.

“But I think it will be a viable option frankly.”

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