The Hydrocarbon Potential Of A Western Portion Of The Lambert Shelf, Dampier Sub-Basin, Western Australia.

Christiansen, David

Honours Degree, 1992

University of Adelaide

Abstract

The hydrocarbon prospectivity of the Enderby Terrace and Lambert she1f areas of the eastern margin of the Dampier Sub-basin are controlled largely by two factors:

1. identifying mature local source rocks
2. identifying migration mechanisms

This is particularly critical to the prospectivity of the Triassic and Jurassic sections since long distance lateral migration through them is considered unlikely due to their faulted nature. Recognition of the probability that the Locker Shale is a good potential source rock in the local deeps formed by back-tilted fault blocks and is within the oil window at approximately 2300m combined with known shows in the Jurassic (Strickland #1) and Triassic (Nickol Bay #1) indicates that hydrocarbon generation has occurred on the Enderby Terrace, thus rendering the Jurassic and Triassic sections prospective.

Most of the Triassic traps are high-risk and fault-dependent. The lateral seal of the middle and upper Dingo Claystone is also a potential risk, due to interbedded sandy intervals. Fault dependent traps involving the basal Triassic sand is a lover risk play as the lateral seal integrity is likely to be better.

The lowest risk plays in the study area occur where the Birdrong Sandstone is draped over Permian/Precambrian horst blocks, such as the Wandoo Field. In this play type the Muderong Shale acts as a good top seal, and source is a lower risk as long distance migration from the Jurassic source rocks within the Lewis Trough is possible. The main stratigraphic play identified within the Cretaceous section is pinchout of the Birdrong Sandstone on the Lambert Shelf. This, however, is seen as a very high risk play.