Abstract

A viable petroleum system must have rock components (source, reservoir and seal) suitably disposed in space and time which when subjected to certain physico-chemical processes in an appropriate framework of time and temperature will result in an economic accumulation of hydrocarbons.

This paper addresses the application of some novel geochemical and petrological methodologies that render better quantification of some of the rock and process components of a petroleum system. Case examples from the NW Shelf, Timor Sea and Papua New Guinea are presented to illustrate the increased confidence in the analysis of various petroleum systems. Two issues are addressed:

(i) use of Strontium isotope chronostratigraphy in thick Tertiary limestone cover for delineation of subsurface structure in the Papuan ford belt. In this region the mountainous and karstic terrain prohibit the acquisition of seismic data for structural mapping and the available conventional correlation tools lack the required resolution.

(ii) assessment of the oil potential of gas discoveries - an issue of importance where the gas discovery is sub economic and/or where the petroleum system analysis identified the targeted structure as having oil charge. Oil bearing fluid inclusions may be the only indication of a palaeo oil charge and its volume. Such inclusions can now be analysed for organic chemical indicators of maturity and source rock characterisation.