THE HYDROCARBON POTENTIAL OF THE DUNTROON BASIN

Abstract

An integrated evaluation of the Duntroon Basin has resulted in the identification of a new petroleum system. Petroleum system components are described in context of the basin-forming passive margin processes, the influence of pre-existing basement controls, and extra-basinal regional tectonic events. An understanding of the controls on the petroleum system components has provided a model for further exploration.

Significant post-rift sequence boundaries are correlated with periodic adjustments in continental spreading rate and azimuth. The implications of these correlations implies that, at least in part, many of the sequences are tectonically controlled.

The evolution of a rift basin neck to the southeast is interpreted to have partially controlled source rock development and reservoir quality through provenance variation in the Early Cretaceous. Synrift lower coastal plain coals and claystones of the Upper Borda Formation deposited in a restricted rift basin segment, are the principal source rock interval in the basin. Timing of hydrocarbon generation and migration for higher potential play fairways is favourable for the entrapment of hydrocarbons in the numerous earlier formed structures. Porosity/depth relationships are excellent and predictive sandstone depositional facies and provenance related porosity/depth trends are demonstrable.

Geochemical analysis of oil shows at Greenly-1 demonstrates the existence of at least two types of migrated oil; one with a distinct terrestrial character and the other a mixed source. Analysis of a Greenly-1 RFT gas sample indicates the existence of migrated thermal gas.