Session 10. Oral Presentation for: Revisiting the rocks discovers turbidites and a new exploration play in the Penola Trough, Otway Basin, South Australia
Sharon Tiainen A *A
Sharon Tiainen is a graduate of the University of Adelaide and has an Honours degree in petroleum geology and geophysics. She has over 25 years’ experience in the upstream oil and gas industry having worked in exploration, appraisal, development, and production roles. She has worked acreage in Algeria, Austria, Australia, Ecuador, Germany, India, Libya, Malaysia, Morocco, Myanmar, the Netherlands, Norway, Papua New Guinea, Pakistan, the Philippines, Romania, Tunisia, Turkey, the UAE, and the United Kingdom. In 2009 she established her own company and most recently she joined the South Australia Department for Energy and Mines and is a member of EAGE, SPE and PESA. |
Abstract
Presented on Wednesday 22 May: Session 10
As part of an integrated geological, geochemical, and geophysical study, conventionally cored intervals from the lower-most stratigraphic section of the onshore South Australian part of the Penola Trough, Otway Basin have been reviewed and reinterpreted. Three conventionally cored wells; Bungaloo-1, Jolly-1ST1 and Sawpit-2, were described using a quick-look approach to determine gross lithological and sedimentological information. Seven lithology types were observed: clay-siltstone with horizontal lamination, diamictite (claystone with horizontal lamination and dropstones), clay-siltstone with massive-horizontal lamination, silt-sandstone with horizontal lamination, sandstone with ripple lamination, sandstone with parallel lamination and sandstone with massive bedding ± rip-up clasts. The first two lithologies are interpreted as representing deposition in a cold climate, profundal-lacustrine depositional environment. The first, containing interpreted varves is the most distal and the second, containing dropstones indicates relatively colder freeze/thaw conditions. The last five lithologies are interpreted as lacustrine turbidite depositional environments, specifically Bouma sequences Te, Td, Tc, Tb and Ta, respectively. Seismic facies interpretation has identified canyon-like and mound features and interpreted them as slope-feeder channels and fan/s respectively, at and away from well control. This rock-based turbidite interpretation provides an alternative to the current alluvial channel/crevasse splay/floodplain lake model for reservoir deposition and as such presents a new exploration play. Further the reservoirs’ immediate lateral association with gas/oil-prone source rocks and seals in the clay-rich lithologies potentially provide for stratigraphic trapping in addition to the previously targeted fault-controlled structural traps.
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Keywords: Australia, core, lacustrine, Otway Basin, play, sedimentology, seismic facies, turbidite.
Sharon Tiainen is a graduate of the University of Adelaide and has an Honours degree in petroleum geology and geophysics. She has over 25 years’ experience in the upstream oil and gas industry having worked in exploration, appraisal, development, and production roles. She has worked acreage in Algeria, Austria, Australia, Ecuador, Germany, India, Libya, Malaysia, Morocco, Myanmar, the Netherlands, Norway, Papua New Guinea, Pakistan, the Philippines, Romania, Tunisia, Turkey, the UAE, and the United Kingdom. In 2009 she established her own company and most recently she joined the South Australia Department for Energy and Mines and is a member of EAGE, SPE and PESA. |
