Unconventional energy sources have become increasingly important to the global energy mix. These include coal seam gas, shale gas and shale oil. The unconventional gas industry was pioneered in the United States and embraced following the first oil shock in 1973 (Rogers). As has been the case with many global resources (Hiscock), many of the same companies that worked in the USA carried their experience in this industry to early Australian explorations. Recently the USA has secured significant energy security with the development of unconventional energy deposits such as the Marcellus shale gas and the Bakken shale oil (Dobb; McGraw). But this has not come without environmental impact, including contamination to underground water supply (Osborn, Vengosh, Warner, Jackson) and potential greenhouse gas contributions (Howarth, Santoro, Ingraffea; McKenna). The environmental impact of unconventional gas extraction has raised serious public concern about the introduction and growth of the industry in Australia.
In coal rich Australia coal seam gas is currently the major source of unconventional gas. Large gas deposits have been found in prime agricultural land along eastern Australia, such as the Liverpool Plains in New South Wales and the Darling Downs in Queensland. Competing land-uses and a series of environmental incidents from the coal seam gas industry have warranted major protest from a coalition of environmentalists and farmers (Berry; McLeish). Conflict between energy companies wanting development and environmentalists warning precaution is an easy script to cast for frontline media coverage. But historical perspectives are often missing in these contemporary debates.
While coal mining and natural gas have often received “boosting” historical coverage (Diamond; Wilkinson), and although historical themes of “development” and “rushes” remain predominant when observing the span of the industry (AGA; Blainey), the history of unconventional gas, particularly the history of its environmental impact, has been little studied. Few people are aware, for example, that the first shale gas exploratory well was completed in late 2010 in the Cooper Basin in Central Australia (Molan) and is considered as a “new” frontier in Australian unconventional gas. Moreover many people are unaware that the first coal seam gas wells were completed in 1976 in Queensland.
The first four wells offer an important moment for reflection in light of the industry’s recent move into Central Australia. By locating and analysing the first four coal seam gas wells, this essay identifies the roots of the unconventional gas industry in Australia and explores the early environmental impact of these wells.
By analysing exploration reports that have been placed online by the Queensland Department of Natural Resources and Mines through the lens of environmental history, the dominant developmental narrative of this industry can also be scrutinised. These narratives often place more significance on economic and national benefits while displacing the environmental and social impacts of the industry (Connor, Higginbotham, Freeman, Albrecht; Duus; McEachern; Trigger). This essay therefore seeks to bring an environmental insight into early unconventional gas mining in Australia. As the author, I am concerned that nearly four decades on and it seems that no one has heeded the warning gleaned from these early wells and early exploration reports, as gas exploration in Australia continues under little scrutiny.
The first four unconventional gas wells in Australia appear at the beginning of the industry world-wide (Schraufnagel, McBane, and Kuuskraa; McClanahan). The wells were explored by Houston Oils and Minerals—a company that entered the Australian mining scene by sharing a mining prospect with International Australian Energy Company (Wiltshire). The International Australian Energy Company was owned by Black Giant Oil Company in the US, which in turn was owned by International Royalty and Oil Company also based in the US. The Texan oilman Robert Kanton held a sixteen percent share in the latter. Kanton had an idea that the Mimosa Syncline in the south-eastern Bowen Basin was a gas trap waiting to be exploited. To test the theory he needed capital. Kanton presented the idea to Houston Oil and Minerals which had the financial backing to take the risk.
Shotover No. 1 was drilled by Houston Oil and Minerals thirty miles south-east of the coal mining town of Blackwater. By late August 1975 it was drilled to 2,717 metres, discovered to have little gas, spudded, and, after a spend of $610,000, abandoned. The data from the Shotover well showed that the porosity of the rocks in the area was not a trap, and the Mimosa Syncline was therefore downgraded as a possible hydrocarbon location. There was, however, a small amount of gas found in the coal seams (Benbow 16). The well had passed through the huge coal seams of both the Bowen and Surat basins—important basins for the future of both the coal and gas industries.
In 1975, while Houston Oil and Minerals was drilling the Shotover well, US Steel and the US Bureau of Mines used hydraulic fracture, a technique already used in the petroleum industry, to drill vertical surface wells to drain gas from a coal seam (Methane Drainage Taskforce 102). They were able to remove gas from the coal seam before it was mined and sold enough to make a profit. With the well data from the Shotover well in Australia compiled, Houston returned to the US to research the possibility of harvesting methane in Australia. As the company saw it, methane drainage was “a novel exploitation concept” and the methane in the Bowen Basin was an “enormous hydrocarbon resource” (Wiltshire 7). The Shotover well passed through a section of the German Creek Coal measures and this became their next target.
In September 1976 the Shotover well was re-opened and plugged at 1499 meters to become Australia’s first exploratory unconventional gas well. By the end of the month the rig was released and gas production tested. At one point an employee on the drilling operation observed a gas flame “the size of a 44 gal drum” (HOMA, “Shotover # 1” 9). But apart from the brief show, no gas flowed. And yet, Houston Oil and Minerals was not deterred, as they had already taken out other leases for further prospecting (Wiltshire 4).
Only a week after the Shotover well had failed, Houston moved the methane search south-east to an area five miles north of the Moura township. Houston Oil and Minerals had researched the coal exploration seismic surveys of the area that were conducted in 1969, 1972, and 1973 to choose the location. Over the next two months in late 1976, two new wells—Kinma No.1 and Carra No.1—were drilled within a mile from each other and completed as gas wells.
Houston Oil and Minerals also purchased the old oil exploration well Moura No. 1 from the Queensland Government and completed it as a suspended gas well. The company must have mined the Department of Mines archive to find Moura No.1, as the previous exploration report from 1969 noted methane given off from the coal seams (Sell). By December 1976 Houston Oil and Minerals had three gas wells in the vicinity of each other and by early 1977 testing had occurred. The results were disappointing with minimal gas flow at Kinma and Carra, but Moura showed a little more promise. Here, the drillers were able to convert their Fairbanks-Morse engine driving the pump from an engine run on LPG to one run on methane produced from the well (Porter, “Moura # 1”).
Although there was not much gas to find in the test production phase, there was a lot of water. The exploration reports produced by the company are incomplete (indeed no report was available for the Shotover well), but the information available shows that a large amount of water was extracted before gas started to flow (Porter, “Carra # 1”; Porter, “Moura # 1”; Porter, “Kinma # 1”). As Porter’s reports outline, prior to gas flowing, the water produced at Carra, Kinma and Moura totalled 37,600 litres, 11,900 and 2,900 respectively. It should be noted that the method used to test the amount of water was not continuous and these amounts were not the full amount of water produced; also, upon gas coming to the surface some of the wells continued to produce water. In short, before any gas flowed at the first unconventional gas wells in Australia at least 50,000 litres of water were taken from underground.
Results show that the water was not ready to drink (Mathers, “Moura # 1”; Mathers, “Appendix 1”; HOMA, “Miscellaneous Pages” 21-24). The water had total dissolved solids (minerals) well over the average set by the authorities (WHO; Apps Laboratories; NHMRC; QDAFF). The well at Kinma recorded the highest levels, almost two and a half times the unacceptable standard. On average the water from the Moura well was of reasonable standard, possibly because some water was extracted from the well when it was originally sunk in 1969; but the water from Kinma and Carra was very poor quality, not good enough for crops, stock or to be let run into creeks. The biggest issue was the sodium concentration; all wells had very high salt levels. Kinma and Carra were four and two times the maximum standard respectively. In short, there was a substantial amount of poor quality water produced from drilling and testing the three wells.
Hydraulic fracturing is an artificial process that can encourage more gas to flow to the surface (McGraw; Fischetti; Senate). Prior to the testing phase at the Moura field, well data was sent to the Chemical Research and Development Department at Halliburton in Oklahoma, to examine the ability to fracture the coal and shale in the Australian wells. Halliburton was the founding father of hydraulic fracture. In Oklahoma on 17 March 1949, operating under an exclusive license from Standard Oil, this company conducted the first ever hydraulic fracture of an oil well (Montgomery and Smith). To come up with a program of hydraulic fracturing for the Australian field, Halliburton went back to the laboratory. They bonded together small slabs of coal and shale similar to Australian samples, drilled one-inch holes into the sample, then pressurised the holes and completed a “hydro-frac” in miniature. “These samples were difficult to prepare,” they wrote in their report to Houston Oil and Minerals (HOMA, “Miscellaneous Pages” 10).
Their program for fracturing was informed by a field of science that had been evolving since the first hydraulic fracture but had rapidly progressed since the first oil shock. Halliburton’s laboratory test had confirmed that the model of Perkins and Kern developed for widths of hydraulic fracture—in an article that defined the field—should also apply to Australian coals (Perkins and Kern). By late January 1977 Halliburton had issued Houston Oil and Minerals with a program of hydraulic fracture to use on the central Queensland wells. On the final page of their report they warned: “There are many unknowns in a vertical fracture design procedure” (HOMA, “Miscellaneous Pages” 17).
In July 1977, Moura No. 1 became the first coal seam gas well hydraulically fractured in Australia. The exploration report states: “During July 1977 the well was killed with 1% KCL solution and the tubing and packer were pulled from the well … and pumping commenced” (Porter 2-3). The use of the word “kill” is interesting—potassium chloride (KCl) is the third and final drug administered in the lethal injection of humans on death row in the USA. Potassium chloride was used to minimise the effect on parts of the coal seam that were water-sensitive and was the recommended solution prior to adding other chemicals (Montgomery and Smith 28); but a word such as “kill” also implies that the well and the larger environment were alive before fracking commenced (Giblett; Trigger).
Pumping recommenced after the fracturing fluid was unloaded. Initially gas supply was very good. It increased from an average estimate of 7,000 cubic feet per day to 30,000, but this only lasted two days before coal and sand started flowing back up to the surface. In effect, the cleats were propped open but the coal did not close and hold onto them which meant coal particles and sand flowed back up the pipe with diminishing amounts of gas (Walters 12). Although there were some interesting results, the program was considered a failure.
In April 1978, Houston Oil and Minerals finally abandoned the methane concept. Following the failure, they reflected on the possibilities for a coal seam gas industry given the gas prices in Queensland: “Methane drainage wells appear to offer no economic potential” (Wooldridge 2). At the wells they let the tubing drop into the hole, put a fifteen foot cement plug at the top of the hole, covered it with a steel plate and by their own description restored the area to its “original state” (Wiltshire 8). Houston Oil and Minerals now turned to “conventional targets” which included coal exploration (Wiltshire 7).
A Thousand Memories
The first four wells show some of the critical environmental issues that were present from the outset of the industry in Australia. The process of hydraulic fracture was not just a failure, but conducted on a science that had never been tested in Australia, was ponderous at best, and by Halliburton’s own admission had “many unknowns”. There was also the role of large multinationals providing “experience” (Briody; Hiscock) and conducting these tests while having limited knowledge of the Australian landscape.
Before any gas came to the surface, a large amount of water was produced that was loaded with a mixture of salt and other heavy minerals. The source of water for both the mud drilling of Carra and Kinma, as well as the hydraulic fracture job on Moura, was extracted from Kianga Creek three miles from the site (HOMA, “Carra # 1” 5; HOMA, “Kinma # 1” 5; Porter, “Moura # 1”). No location was listed for the disposal of the water from the wells, including the hydraulic fracture liquid. Considering the poor quality of water, if the water was disposed on site or let drain into a creek, this would have had significant environmental impact. Nobody has yet answered the question of where all this water went. The environmental issues of water extraction, saline water and hydraulic fracture were present at the first four wells.
At the first four wells environmental concern was not a priority. The complexity of inter-company relations, as witnessed at the Shotover well, shows there was little time. The re-use of old wells, such as the Moura well, also shows that economic priorities were more important. Even if environmental information was considered important at the time, no one would have had access to it because, as handwritten notes on some of the reports show, many of the reports were “confidential” (Sell). Even though coal mines commenced filing Environmental Impact Statements in the early 1970s, there is no such documentation for gas exploration conducted by Houston Oil and Minerals. A lack of broader awareness for the surrounding environment, from floral and faunal health to the impact on habitat quality, can be gleaned when reading across all the exploration reports.
Nearly four decades on and we now have thousands of wells throughout the world. Yet, the challenges of unconventional gas still persist. The implications of the environmental history of the first four wells in Australia for contemporary unconventional gas exploration and development in this country and beyond are significant. Many environmental issues were present from the beginning of the coal seam gas industry in Australia. Owning up to this history would place policy makers and regulators in a position to strengthen current regulation. The industry continues to face the same challenges today as it did at the start of development—including water extraction, hydraulic fracturing and problems associated with drilling through underground aquifers.
Looking more broadly at the unconventional gas industry, shale gas has appeared as the next target for energy resources in Australia. Reflecting on the first exploratory shale gas wells drilled in Central Australia, the chief executive of the company responsible for the shale gas wells noted their deliberate decision to locate their activities in semi-desert country away from “an area of prime agricultural land” and conflict with environmentalists (quoted in Molan). Moreover, the journalist Paul Cleary recently complained about the coal seam gas industry polluting Australia’s food-bowl but concluded that the “next frontier” should be in “remote” Central Australia with shale gas (Cleary 195). It appears that preference is to move the industry to the arid centre of Australia, to the ecologically and culturally unique Lake Eyre Basin region (Robin and Smith). Claims to move the industry away from areas that might have close public scrutiny disregard many groups in the Lake Eyre Basin, such as Aboriginal rights to land, and appear similar to other industrial projects that disregard local inhabitants, such as mega-dams and nuclear testing (Nixon).
AGA (Australian Gas Association). “Coal Seam Methane in Australia: An Overview.” AGA Research Paper 2 (1996).
Apps Laboratories. “What Do Your Water Test Results Mean?” Apps Laboratories 7 Sept. 2012. 1 May 2013 ‹http://appslabs.com.au/downloads.htm›.
Benbow, Dennis B. “Shotover No. 1: Lithology Report for Houston Oil and Minerals Corporation.” November 1975. Queensland Digital Exploration Reports. Company Report 5457_2. Brisbane: Queensland Department of Resources and Mines 4 June 2012. 1 May 2013 ‹https://qdexguest.deedi.qld.gov.au/portal/site/qdex/search?REPORT_ID=5457&COLLECTION_ID=999›.
Berry, Petrina. “Qld Minister Refuses to Drink CSG Water.” news.com.au, 22 Apr. 2013. 1 May 2013 ‹http://www.news.com.au/breaking-news/national/qld-minister-refuses-to-drink-csg-water/story-e6frfku9-1226626115742›.
Blainey, Geofrey. The Rush That Never Ended: A History of Australian Mining. Carlton: Melbourne University Publishing, 2003.
Briody, Dan. The Halliburton Agenda: The Politics of Oil and Money. Singapore: Wiley, 2004.
Cleary, Paul. Mine-Field: The Dark Side of Australia’s Resource Rush. Collingwood: Black Inc., 2012.
Connor, Linda, Nick Higginbotham, Sonia Freeman, and Glenn Albrecht. “Watercourses and Discourses: Coalmining in the Upper Hunter Valley, New South Wales.” Oceania 78.1 (2008): 76-90.
Diamond, Marion. “Coal in Australian History.” Coal and the Commonwealth: The Greatness of an Australian Resource. Eds. Peter Knights and Michael Hood. St Lucia: University of Queensland, 2009. 23-45. 20 Apr. 2013 ‹http://www.peabodyenergy.com/mm/files/News/Publications/Special%20Reports/coal_and_commonwealth%5B1%5D.pdf›.
Dobb, Edwin. “The New Oil Landscape.” National Geographic (Mar. 2013): 29-59.
Duus, Sonia. “Coal Contestations: Learning from a Long, Broad View.” Rural Society Journal 22.2 (2013): 96-110.
Fischetti, Mark. “The Drillers Are Coming.” Scientific American (July 2010): 82-85.
Giblett, Rod. “Terrifying Prospects and Resources of Hope: Minescapes, Timescapes and the Aesthetics of the Future.” Continuum: Journal of Media and Cultural Studies 23.6 (2009): 781-789.
Hiscock, Geoff. Earth Wars: The Battle for Global Resources. Singapore: Wiley, 2012.
HOMA (Houston Oil and Minerals of Australia). “Carra # 1: Well Completion Report.” July 1977. Queensland Digital Exploration Reports. Company Report 6054_1. Brisbane: Queensland Department of Resources and Mines. 21 Feb. 2012 ‹https://qdexguest.deedi.qld.gov.au/portal/site/qdex/search?REPORT_ID=6054&COLLECTION_ID=999›.
———. “Kinma # 1: Well Completion Report.” August 1977. Queensland Digital Exploration Reports. Company Report 6190_2. Brisbane: Queensland Department of Resources and Mines. 21 Feb. 2012 ‹https://qdexguest.deedi.qld.gov.au/portal/site/qdex/search?REPORT_ID=6190&COLLECTION_ID=999›.
———. “Miscellaneous Pages. Including Hydro-Frac Report.” August 1977. Queensland Digital Exploration Reports. Company Report 6190_17. Brisbane: Queensland Department of Resources and Mines. 31 May 2012 ‹https://qdexguest.deedi.qld.gov.au/portal/site/qdex/search?REPORT_ID=6190&COLLECTION_ID=999›.
———. “Shotover # 1: Well Completion Report.” March 1977. Queensland Digital Exploration Reports. Company Report 5457_1. Brisbane: Queensland Department of Resources and Mines. 22 Feb. 2012 ‹https://qdexguest.deedi.qld.gov.au/portal/site/qdex/search?REPORT_ID=5457&COLLECTION_ID=999›.
Howarth, Robert W., Renee Santoro, and Anthony Ingraffea. “Methane and the Greenhouse-Gas Footprint of Natural Gas from Shale Formations: A Letter.” Climatic Change 106.4 (2011): 679-690.
Mathers, D. “Appendix 1: Water Analysis.” 1-2 August 1977. Brisbane: Government Chemical Laboratory. Queensland Digital Exploration Reports. Company Report 6054_4. Brisbane: Queensland Department of Resources and Mines. 21 Feb. 2012 ‹https://qdexguest.deedi.qld.gov.au/portal/site/qdex/search?REPORT_ID=6054&COLLECTION_ID=999›.
———. “Moura # 1: Testing Report Appendix D Fluid Analyses.” 2 Aug. 1977. Brisbane: Government Chemical Laboratory. Queensland Digital Exploration Reports. Company Report 5991_5. Brisbane: Queensland Department of Resources and Mines. 22 Feb. 2012 ‹https://qdexguest.deedi.qld.gov.au/portal/site/qdex/search?REPORT_ID=5991&COLLECTION_ID=999›.
McClanahan, Elizabeth A. “Coalbed Methane: Myths, Facts, and Legends of Its History and the Legislative and Regulatory Climate into the 21st Century.” Oklahoma Law Review 48.3 (1995): 471-562.
McEachern, Doug. “Mining Meaning from the Rhetoric of Nature—Australian Mining Companies and Their Attitudes to the Environment at Home and Abroad.” Policy Organisation and Society (1995): 48-69.
McGraw, Seamus. The End of Country. New York: Random House, 2011.
McKenna, Phil. “Uprising.” Matter 21 Feb. 2013. 1 Mar. 2013 ‹https://www.readmatter.com/a/uprising/›.McLeish, Kathy. “Farmers to March against Coal Seam Gas.” ABC News 27 Apr. 2012. 22 Apr. 2013 ‹http://www.abc.net.au/news/2012-04-27/farmers-to-march-against-coal-seam-gas/3977394›.
Methane Drainage Taskforce. Coal Seam Methane. Sydney: N.S.W. Department of Mineral Resources and Office of Energy, 1992.
Molan, Lauren. “A New Shift in the Global Energy Scene: Australian Shale.” Gas Today Online. 4 Nov. 2011. 3 May 2012 ‹http://gastoday.com.au/news/a_new_shift_in_the_global_energy_scene_australian_shale/064568/›.
Montgomery, Carl T., and Michael B. Smith. “Hydraulic Fracturing: History of an Enduring Technology.” Journal of Petroleum Technology (2010): 26-32. 30 May 2012 ‹http://www.spe.org/jpt/print/archives/2010/12/10Hydraulic.pdf›.
NHMRC (National Health and Medical Research Council). National Water Quality Management Strategy: Australian Drinking Water Guidelines 6. Canberra: Australian Government, 2004. 7 Sept. 2012 ‹http://www.nhmrc.gov.au/guidelines/publications/eh52›.
Nixon, Rob. “Unimagined Communities: Developmental Refugees, Megadams and Monumental Modernity.” New Formations 69 (2010): 62-80.
Osborn, Stephen G., Avner Vengosh, Nathaniel R. Warner, and Robert B. Jackson. “Methane Contamination of Drinking Water Accompanying Gas-Well Drilling and Hydraulic Fracturing.” Proceedings of the National Academy of Sciences 108.20 (2011): 8172-8176.
Perkins, T.K., and L.R. Kern. “Widths of Hydraulic Fractures.” Journal of Petroleum Technology 13.9 (1961): 937-949.
Porter, Seton M. “Carra # 1:Testing Report, Methane Drainage of the Baralaba Coal Measures, A.T.P. 226P, Central Queensland, Australia.” Oct. 1977. Queensland Digital Exploration Reports. Company Report 6054_7. Brisbane: Queensland Department of Resources and Mines. 21 Feb. 2012 ‹https://qdexguest.deedi.qld.gov.au/portal/site/qdex/search?REPORT_ID=6054&COLLECTION_ID=999›.
———. “Kinma # 1: Testing Report, Methane Drainage of the Baralaba Coal Measures, A.T.P. 226P, Central Queensland, Australia.” Oct. 1977. Queensland Digital Exploration Reports. Company Report 6190_16. Brisbane: Queensland Department of Resources and Mines. 21 Feb. 2012 ‹https://qdexguest.deedi.qld.gov.au/portal/site/qdex/search?REPORT_ID=6190&COLLECTION_ID=999›.
———. “Moura # 1: Testing Report: Methane Drainage of the Baralaba Coal Measures: A.T.P. 226P, Central Queensland, Australia.” Oct. 1977. Queensland Digital Exploration Reports. Company Report 6190_15. Brisbane: Queensland Department of Resources and Mines. 21 Feb. 2012 ‹https://qdexguest.deedi.qld.gov.au/portal/site/qdex/search?REPORT_ID=6190&COLLECTION_ID=999›.
QDAFF (Queensland Department of Agriculture, Fisheries and Forestry). “Interpreting Water Analysis for Crop and Pasture.” 1 Aug. 2012. 1 May 2013 ‹http://www.daff.qld.gov.au/ 26_4347.htm›.
Robin, Libby, and Mike Smith. “Prologue.” Desert Channels: The Impulse To Conserve. Eds. Libby Robin, Chris Dickman and Mandy Martin. Collingwood: CSIRO Publishing, 2010. XIII-XVII.
Rogers, Rudy E. Coalbed Methane: Principles and Practice. Englewood Cliffs: Prentice Hill, 1994.
Sell, B.H. “T.E.P.L. Moura No.1 Well Completion Report.” October 1969. Queensland Digital Exploration Reports. Company Report 2899_1. Brisbane: Queensland Department of Resources and Mines. 26 Feb. 2013 ‹https://qdexguest.deedi.qld.gov.au/portal/site/qdex/search?REPORT_ID=2899&COLLECTION_ID=999›.
Senate. Management of the Murray Darling Basin: Interim Report: The Impact of Coal Seam Gas on the Management of the Murray Darling Basin. Canberra: Rural Affairs and Transport References Committee, 2011.
Schraufnagel, Richard, Richard McBane, and Vello Kuuskraa. “Coalbed Methane Development Faces Technology Gaps.” Oil & Gas Journal 88.6 (1990): 48-54.
Trigger, David. “Mining, Landscape and the Culture of Development Ideology in Australia.” Ecumene 4 (1997): 161-180.
Walters, Ronald L. Letter to Dennis Benbow. 29 August 1977. In Seton M. Porter, “Moura # 1: Testing Report: Methane Drainage of the Baralaba Coal Measures: A.T.P. 226P, Central Queensland, Australia.” October 1977, 11-14. Queensland Digital Exploration Reports. Company Report 6190_15. Brisbane: Queensland Department of Resources and Mines. 21 Feb. 2012 ‹https://qdexguest.deedi.qld.gov.au/portal/site/qdex/search?REPORT_ID=6190&COLLECTION_ID=999›.
WHO (World Health Organization). International Standards for Drinking-Water. 3rd Ed. Geneva, 1971.
Wilkinson, Rick. A Thirst for Burning: The Story of Australia's Oil Industry. Sydney: David Ell Press, 1983.
Wiltshire, M.J. “A Review to ATP 233P, 231P (210P) – Bowen/Surat Basins, Queensland for Houston Oil Minerals Australia, Inc.” 19 Jan. 1979. Queensland Digital Exploration Reports Database. Company Report 6816. Brisbane: Queensland Department of Resources and Mines. 21 Feb. 2012 ‹https://qdexguest.deedi.qld.gov.au/portal/site/qdex/search?REPORT_ID=6816&COLLECTION_ID=999›.
Wooldridge, L.C.P. “Methane Drainage in the Bowen Basin – Queensland.” 25 Aug. 1978. Queensland Digital Exploration Reports Database. Company Report 6626_1. Brisbane: Queensland Department of Resources and Mines. 31 May 2012 ‹https://qdexguest.deedi.qld.gov.au/portal/site/qdex/search?REPORT_ID=6626&COLLECTION_ID=999›.