Print this pageSubsalt Exploration in Australia's Amadeus Basin
PEGUM, D. M.
The discovery of a thin wet gas zone in the previously undrilled basal sandstone of Australia's Amadeus Basin has opened up a major new regionally extensive exploration play.
The Amadeus Basin is an underexplored, petroleum producing intracratonic basin covering 70,000 square miles in Central Australia and containing up to 45,000 feet of Neoproterozoic to Devonian shallow marine to continental sediments. Spectacular surface anticlines have attracted petroleum explorers for over forty years. Two major fields, Mereenie Oil and Gas Field and Palm Valley Gas Field produce from Cambro-Ordovician sandstone reservoirs. The presence of thick salt in the Neoproterozoic Bitter Springs Formation has in the past deterred deeper exploration. Many structures were known to be salt induced and the subsalt structure could not be mapped successfully.
Recent high resolution seismic has successfully imaged the subsalt structure. Air drilling has proved highly efficient in the first well drilled through the subsalt section to metamorphic basement. The Heavitree Quartzite which occurs between the Bitter Springs Formation and basement, normally over 100 meters in thickness, was only 4.5 meters where intersected in the well. it had a porosity of 9%, and flowed 63.1 mscfd of wet gas containing 6.23% helium from an estimated 3.6 meter net pay zone.
This shows there is potential for major structural and stratigraphic traps in the area and opens up for exploration a large region where the Heavitree is potentially much thicker.