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ABSTRACT: Palaeogeographic Controls on pre-Tertiary Source Rock Distribution on the Northern Australian Continental Margin

Livsey, Andrew R.1 and Tim R. Charlton2
(1) PT Robertson Utama Indonesia, Jakarta, Indonesia 
(2) Consultant, Guildford, Surrey, United Kingdom

The distribution of pre-Tertiary source rocks on the northern part of the Australian continent is poorly understood due to the lack of well penetrations and the large extent of the area. Source rock indications have however been noted from throughout the area and at many stratigraphic levels, ranging from Cambrian to Cretaceous. A key to predicting their distribution and type is an understanding of the palaeogeographies for the principal source rock time slices and knowledge of the controls on source rock development.

Palaeogeographic maps have been compiled for a series of time-slices ranging from Maastrichtian to Early Permian, based on published information, well data and tectonic reconstruction for an area including the Northwest Shelf, eastern Indonesia and Papua New Guinea.

Source rock data have also been compiled and interpreted to understand the nature of the source rock systems. These results have then been integrated with the palaeogeographic reconstructions in order to predict source rock play fairways over the area. In areas where source rock indications are rare or absent, the source rock model has been extrapolated from the results of analyses of oils and gases.

The results of these source rock interpretations indicate that source rocks may have been deposited over large parts of this area during particular time-periods thus upgrading the hydrocarbon prospectivity of largely undrilled acreage.

AAPG Search and Discovery Article #90913©2000 AAPG International Conference and Exhibition, Bali, Indonesia