‘Mighty Mungaroo’ Pays Off
Aussie Geologists Look to the West
Western Australia has received increasing attention lately as the place to be if you’re looking for big hydrocarbon finds.
A look at the reserves numbers says it all.
The state is the major oil and gas producer in Australia, with 2004 reserves tallying 135 gigalitres of oil, 282 gigalitres of condensate and 3,408 cubic gigametres of gas, according to the Western Australia Department of Industry and Resources.
Petroleum prospectivity has been demonstrated both onshore and offshore Western Australia, and a non-threatening political climate further enhances the region’s appeal for the prospectors and operators.
The lure of the area increased significantly with the recent announcement of Chevron’s successful Clio-1 well, which was completed in September 2006 offshore northwestern Australia in Permit WA-205-P.
The well discovered 623 feet of net gas sands, making it one of the top wells in Australia in terms of total net pay, according to Chevron.
Transocean’s semi-submersible rig Jack Bates was used to drill the well in approximately 3,000 feet of water; total vertical drilling depth was 15,500 feet.
Chevron Australia and Texaco Australia Pty Ltd operate permit WA-205-P and hold a 67 percent interest. Shell Development Australia holds the remaining 33 percent.
The pay zone in the Clio-1 is the Triassic Mungaroo formation, which AAPG member Peter Baillie, chief geologist Asia Pacific at TGS-NOPEC, labels “Mighty Mungaroo.” He noted the fluvial sandstone can have multi-darcy porosity at four kilometers of depth.
The Clio-1 is in the region of the giant multi-field Greater Gorgon complex, and its successful completion came on the heels of another Chevron deepwater gas find made by the Chandon-1 well, which was announced in July. The Chandon-1 was drilled by the Jack Bates in 3,900 feet of water, with total drilling depth reaching 10,200 feet.
The well is about 160 miles offshore northwestern Australia, within reach of the Greater Gorgon development area. Chevron has a 100 percent interest in the Chandon-1.
Look for a flurry of follow-up activity related to the Clio-1 discovery.
“We are undertaking further work on the discovery -- including a 40-day, 463- square-mile (1,200-square-kilometer) 3-D seismic survey starting mid-December,” said Scott Walker, media adviser at Chevron Australia, “to better determine the potential of the gas find and its subsequent development.”
The Gorgon complex is unique in having a high CO2 content, but indications are the gas deposit tapped by the Clio-1 is low in CO2, according to Walker.
The potential is great for any number of follow-up discoveries by the company.
Walker noted Chevron Australia is among the largest holders of gas in Australia, (about 25 percent of the country’s undeveloped gas). As of 2006, the company had an operated interest in 15,000 square miles of acreage in Australia and a non-operator interest in approximately 10,400 square miles of acreage. Eighty percent of this is located offshore northwestern Australia.
The company’s 2006 exploration budget in these interests tallied $190 million.
Chevron has partnered with Royal Dutch Shell and ExxonMobil in a proposed LNG facility to be built on Barrow Island in the Gorgon vicinity. Chevron will operate the installation and holds a 50 percent stake with the remainder allocated equally to the two partners. Currently, the LNG plant remains stalled in the approval process.
The sizeable quantities of CO2 present in the gas produced from the Gorgan complex would be compressed and injected into a static aquifer on Barrow Island near the LNG facility.