Publication Name: PESA's Eastern Australasian Basin Symposium II
Authors: R.K. Merrill, S.K. Trujillo, S.D. Simpson and R.M. Wall
Date Published: December 2004
Number of Pages: 23
Reference Type: Book Section
Abstract:
Since 1971, Samson, headquartered in Tulsa, Oklahoma, has grown primarily through acquisitions and development to be a significant independent oil and gas company in North America. From the beginning, the company's focus has been and remains on quality production and exploration assets, weighted towards natural gas. Building on early success in the Anadarko and Arkoma basins, Samson has developed 30 years of expertise successfully developing tight gas sand plays. The Bowen Basin became Samson's focus in Australia because of its natural gas potential, the prospect for a growing gas market, and the fact it is considered relatively underexploited.The Upper Permian in the Bowen Basin is similar to many of the tight gas reservoirs Samson manages in the United States. The intercalated coal measures are the likely source of the gas with minor contribution of hydrocarbons from mature marine shales of the Black Alley Shale. These hydrocarbons have charged the Upper Permian so that it is slightly overpressured. The lack of free water in the downdip portions of the basin suggests that gas is ubiquitous and the gas system is a basin centered gas accumulation. Potential reservoirs are interbedded with the coal measures of the Upper Permian and stratigraphic pinchouts provide additional trapping.
Bowen Basin exploration history suggests that insufficient consideration was given to potential formation damage while drilling and completing wells in the Permian. These reservoirs are not unlike those in Samson's core production areas. Subsequent to Samson's decision to enter Australia and test this play concept at Overston, Mosaic Oil NL and Oil Company of Australia Ltd, a wholly owned subsidiary of Origin Energy Ltd, have successfully commercialized this play in part through using under-balanced drilling at Churchie and Myall Creek.