ABSTRACT: The Sequence Stratigraphy, Structure and Petroleum Potential of the Vlaming Subbasin

SEGGIE, ROBERT, Santos, Toorak Gardens, South Australia, Australia

The Vlaming subbasin, offshore Perth, Western Australia, contains up to 16 km of Permian to Cainozoic sediments. The complex structure and stratigraphy of the Subbasin have prevented effected petroleum exploration in the past. High-resolution seismic, seismic stratigraphy and the much fine micropaleontological subdivision of the sedimentary section have enabled the key Neocomian and Barremian unit (spanning 25 m.y. and up to 6000 m) to be subdivided into ten time zones so that the complex facies variations could be mapped. This shows that only two wells out of the ten drilled in the study area intersected valid traps. Both, Gage Roads 1 and 2, intersected oil pools.

A brief mid Valangian hiatus coincided with intense structuring causing complex faulting and extensive erosion. Very rapid sedimentation preceded structuring with up to 6000 m of fluvio-lacustrine, paralic, and lacustrine sediments deposited during the Berriasian to early Valangianian (1000 m/m.y.). Slower sedimentation followed structuring in open marine, restricted marine, paralic and fluvio-deltaic environments (100 m/m.y.). The renewed deposition occurred in topographic lows in a paralic environment and coincided with the cessation of structuring, with the formation of the first oceanic crust

in the Perth Abyssal Plain and with a major drop in sea level.

Considerable petroleum exploration potential exists in the sparsely explored Vlaming Subbasin with the presence of three regional sealing units, two very thick sandstone reservoir units, complex structure and mature oil prone coaly source units. Numerous trapping mechanisms exist and significant hydrocarbon pools could occur.

AAPG Search and Discovery Article #91015©1992 AAPG International Conference, Sydney, N.S.W., Australia, August 2-5, 1992 (2009)