Publication Name: Eastern Australian Basins Symposium III (EABS 2008)
Authors: R. Sykes and J.I. Raine
Date Published: September 2008
Number of Pages: 6
Abstract:
Late Cretaceous coaly rocks are the primary source of petroleum in the offshore Taranaki Basin and have sourced medium-sized, black (i.e. non-volatile) oil accumulations in the Tui (50 MMbbl), Maari (49 MMbbl) and Maui-B (30 MMbbl) fields. The Rakopi Formation is likely to be the dominant source unit on the grounds of both source rock volume and maturity, but the Wainui and Puponga coal measure members of the North Cape Formation are also expected to have expelled significant volumes of oil from some kitchen areas. The oil potential of their coaly facies—like that of humic coaly facies in general—is highly variable, making kerogen quality a major component of charge risk. In this paper, quantitative pyrolysis-gas chromatography (PyGC) results are integrated with bulk geochemical, petrographic and palynological data for an extensive set of North Cape Formation coaly rock samples to identify the key organofacies controls on their oil potential. As the terrestrially sourced oils of the Taranaki Basin are typically waxy and paraffinic, the main emphasis of the paper is on non-volatile, paraffinic oil potential.