Queensland’s Department of Natural Resources and Mines, working with industry response teams, successfully stabilised and capped a long-abandoned coal exploration test hole at Kogan on the Darling Downs that had been the site of a slow-burning fire. The 32-year-old coal exploration borehole ignited in late August 2012 causing a small bush fire near the Kogan-Dalby road. The initial fire was extinguished quickly by the Queensland Fire and Rescue Authority and an extensive risk assessment and plan of action was put in place in consultation with local landholders to safely cap the abandoned borehole.Departmental officers worked in partnership with industry teams from Peabody Coal, Arrow Energy, Easternwell and Linc Energy to extinguish the shallow flame and stabilise the site in two stages.
The team pumped water into the 140 m deep hole then let it cool while they observed it over the following 24 hours. After the site had cooled, the old test bore was plugged with concrete. The site was monitored for several days, and then rehabilitated.
The incident highlighted the potential for historical bores that have not been abandoned appropriately to release methane if “free” (desorbed) methane is present in the coal seam. Desorbed methane is released from the saturated pore space in the coal and able to travel through the coal seam to the surface via natural fractures or artificial features such as bores.
The Mine Safety and Health Commissioner Stewart Bell said he was pleased the incident response involved government and industry working together. “From a safety perspective, the risk to workers and the public was minimal because exploration bores like this are generally in remote locations and with methane being lighter than air it does dissipate very quickly but with fire season upon us, this is a good case study in how an urgent incident response should be handled,” said Bell.
The Inspectorate and the Minister recently met the incident response team and industry peak bodies including the Australian Petroleum Production and Exploration Association and the Queensland Resources Council to discuss how similar events in the future could be handled and to share what was learned from the Kogan incident.
It was agreed that a number of proactive measures could be introduced to ensure a longer term strategic approach for dealing with fugitive emissions from abandoned exploration and water bores.
Risk management strategies will be examined carefully to minimise the risk of historical bores that have not been abandoned appropriately.
A draft protocol has been developed by industry and DNRM to outline the key principles and approach that will be taken should a similar event occur again. This protocol was expected to be in place by late November 2012.
Longer-term liability, obligations and necessary legislative provisions to address legacy issues from incorrectly abandoned bores and wells, water bores and natural water features will be subject to the normal consultative and legislative processes.
Some exploration and water bores were drilled in decades past when the legislative safeguards on well construction and rehabilitation of sites were not as strict as they are today.
These practices would not be allowed to occur under contemporary safety laws but proactive short term and long term solutions will be rolled out in partnership with industry, landholders and technical experts in the field to address these issues responsibly.