Petroleum potential and oil‐source correlation in the Great South and Canterbury Basins

Abstract

Abstract Pyrolytic analyses suggest that Cretaceous coaly sediments in the Great South and Canterbury Basins, southeast and east of South Island, New Zealand, exhibit mixed oil and gas potential, like their counterparts in Taranaki Basin. On the basis of isotopic and biomarker characteristics together with maturity considerations, mid‐Cretaceous coaly sediments are the most likely sources of the condensate and oil shows in Kawau‐1A well (Great South Basin), oil shows in deep Cretaceous strata in Clipper‐1 and Galleon‐1 wells (Canterbury Basin), and the stains in beach sands in northeastern Stewart Island. An oil stain in the upper Cretaceous in Galleon‐1 well is consistent with a Late Cretaceous coal source. Although some marine strata have petroleum potential, particularly the Tartan Member (equivalent of the latest Paleocene Waipawa Black Shale), they are often immature, and oils generated from such sources have yet to be discovered.