The characterisation and provenance of crude oils stranded on the South Australian coastline. Part II: Potential parent petroleum systems.

In 2014-2016 more than 600 specimens of semi-solid crude oil were recovered from 30 ocean beaches along the coastline of South Australia, as part of the recently completed Great Australian Bight Research Program. All are believed to be products of submarine oil seepage. Their source-specific biomarker signatures provide the basis for their assignment to sixteen oil families, some previously unrecognised.

The characterisation and provenance of crude oils stranded on the South Australian coastline. Part I: Oil types and their weathering.

Semi-solid crude oil has been known to wash ashore along the South Australian coastline for over 120 years. The early reports pre-date offshore petroleum exploration and tanker shipping activities in Australian waters, suggesting that this stranded oil originates from natural offshore seepage. Three physically distinct varieties are represented: waxy bitumen, asphaltite and tar.

The natural hydrocarbon loading of the South Australian coastline.

Crude oil released from natural offshore seeps may strand in coastal environments. Understanding the different types of oil which accumulate on a given coastline, in addition to their spatial distribution and abundance, may be used to establish an environmental baseline for natural "background" petroleum contamination. Here we summarise the hydrocarbon loading of thirty beaches on Australia's southern margin based on three annual surveys in 2014-2016.

Remotely constraining the temporal evolution of offshore oil systems.

An understanding of the temporal evolution of a petroleum system is fundamental to interpreting where hydrocarbons may be trapped in the subsurface. However, traditional exploration methods provide few absolute constraints on the timing of petroleum generation. Here we show that Re/Os geochronology may be applied to natural crude oil seepage to determine when petroleum generation occurred in offshore sedimentary basins.