Application of
Fault Plane Attribute Mapping in the Gambier Embayment of the Onshore
Boult, Peter J.1,
Sandy Menpes2, Gordon Wakelin-king2 (1) PIRSA, Adelaide,
Australia (2) Essential Petroleum, Victoria, Australia
The rift-sag-rift
3D interpretation of 2D seismic and
display of fault plane attributes in the Gambier Embayment reduces exploration
risk in an area with significant, but as yet undeveloped, petroleum potential.
Wet gas seeps, asphaltite strandings
and oil shows are evidence of a working petroleum system with marine, type II
source rocks. Non-commercial oil, along with commercial CO2 is produced from
the base of the Late Cretaceous in Caroline-1 and “oil sands” were described at
the base of the Tertiary in SAOW-2 in 1926. Juxtaposition of marine shales against fluvial/marginal marine sands in fault
bounded, 3-way dip closures and horsts are the main trapping mechanisms and
there is good potential for shale gouge seal development.
Karst topography
significantly degrades the seismic signal in many places, but fault plane modelling and displacement mapping reduces interpretation
risk by providing confidence in fault correlation and a robust understanding of
cross-fault geometries. Three sets of faults are distinguishable, being early
NW–SE basement related faults, later NNW–SSE cover faults, which show
displacement highs at the K/T boundary, and neotectonic
ENE–WSW thrust faults.
Interpretation demonstrates shale beds of
at least 220m and 240m thick are needed to provide robust juxtaposition seals
for the Harris Flat lead at the top Flaxman and Waarre formations respectively. Nearby well intersections
indicate that shale beds will have sufficient thickness.
AAPG Search and Discover Article #90063©2007 AAPG Annual Convention, Long Beach, California