Two wells drilled in Australia’s Lawn and Riversleigh Shales showed Total Organic Carbon (TOC) level over twice the amount of that seen in world class shales such as the Marcellus in the U.S.
The Egilabria 2 and 4 wells, drilled by Armour Energy in the recently recognized hydrocarbon province in northern Australia, were the first lateral wells in the country to flow gas from a hydraulically fractured shale formation.
Detailed source rock analysis recorded in the two wells drilled TOC levels of up to 11% in sweet spots at the two shales, well above the 5% TOCs of the U.S. shales.
Total Organic Carbon (TOC) is one of the key measures for a shale formation to be economically viable as it provides a measure for the capacity of the rock to generate hydrocarbons. A typical minimum TOC required for a shale is 2%. Worldclass TOCs, such as seen in the commercial Marcellus Shale in the USA, are in excess of 5%.
The gas produced by Egilabria 2 shows a very high methane content (90%), ethane (0.5%) and very little CO2 (2%), helium (1%) and other inert gases (6.5%). This low CO2 content is considered very positive as it alleviates any requirements for major gas processing facilities during the development phase, including CO2 sequestration facilities.
Additional analysis confirmed gas desorption and showed the gas to be thermogenic in origin.
The impressive results from the Egilabria wells supports Armour’s belief that the Lawn and Riversleigh Formations within the Isa Superbasin of Northern Australia have amongst the highest Total Organic Carbon (TOC) content of any shale play in Australia.
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