Geological characterisation and natural gas potential of the non-marine Roseneath and Murteree Shales, Cooper Basin, central Australia
Lendyn Marcus Philip, B.Sc.
Project submitted in partial fulfilment of the requirements for the degree of MSc (Energy and Resources), UCL Australia.
Underexplored basins worldwide could have significant shale gas potential, previously overlooked, if a combination of Facies analysis, chemostratigraphy and palaeo-environmental studies are combined with basic well log data collected historically to provide new framework.
The geological characteristics of commercially producing shale gas plays vary widely. Yet the majority of commercially producing plays seem to have been formed in a marine environment, suggesting that non-marine shales are less prospective. The rationale being that non-marine environments are richer in clay minerals and less amenable to hydraulic fracturing.
This research developed and partially applied a framework methodology to screen prospective shale gas plays in terms of key subsurface criteria.
The results show that both non-marine formations compare similarly to marine analogues in terms of thickness, total organic content, thermal maturity of organic matter, natural gas content and Poisson’s ratio. High carbon dioxide content, high clay mineral content and low values for Young’s modulus distinguish the lacustrine Roseneath and Murteree Shales from marine gas shales in the USA. Overall, these variables negatively affect a well’s ultimate recovery of gas, and therefore economics should be considered before deeming the formations non-prospective.
The analysis presented suggests that facies analysis is useful for the identification and prioritisation of gas rich zones, and that integration of chemostratigraphy with palaeo-environmental studies may produce a robust stratigraphic framework for shale gas exploration and appraisal in the Cooper Basin.