1.2.3.2.1 History of coal seam gas exploration

The Galilee Basin was first explored for conventional hydrocarbons during the late 1950s and 1960s. This work involved regional seismic surveying and drilling of over 40 exploration wells, many to depths of about 3000 or 4000 m. However, results were generally not encouraging as most wells reported no hydrocarbons. An exception, well Lake Galilee 1 drilled in 1964 resulted in recovery of minor oil (uneconomic quantities) from a conventional sandstone reservoir. As a result of the overall poor exploration success, hydrocarbon exploration stalled in the 1970s with only ten wells drilled. There was some renewed interest in the 1980s (about 25 new wells) although, as before, exploration results were generally poor.

Since the early 1990s the main focus of hydrocarbon exploration in the Galilee Basin has been on the potential for CSG resources. This began with the pioneering work of Enron Exploration Australia Pty Ltd (EEA), when drilling of the Fleetwood, Splitters Creek and Rodney Creek wells targeted the Betts Creek beds and the Aramac Coal Measures at depths greater than 1000 m (Blue Energy, 2010). The Rodney Creek 1 well encountered a significant thickness of net coal (35 m), with moderate to good natural permeability (2 to 35 millidarcies). During drill-stem testing both gas and water naturally flowed, indicating in situ fractured coal and relatively high level of gas saturation (EEA, 1992). This initial exploration effort provided evidence that CSG could be extracted from the coal-bearing Permian Galilee Basin, although this did not lead to an immediate substantial increase in further drilling or CSG-focused exploration.