Calibrated Prediction of Hydrocarbon Fluid Type in Frontier Basins of Australia

Abstract

There is potential for a new oil province in Australia’s expansive and geological diverse EEZ with multiple oil fields having a value to the nation measured in $billion. To screen this large area requires appropriate technologies such as direct detection of leaking hydrocarbons or inferring the nature of petroleum systems from dredge samples or old exploratory wells. A common risk is that hydrocarbon charge and petroleum systems are not proven. Inclusions of oil in sedimentary grains detect migratory oil and can be used to deduce key parameters of petroleum systems that are critical for predicting the fluid type.

Fluorescence spectra of oil inclusions broadly correlate with API gravity. Spectra with computed CIE chromaticity coordinates in the blue part of the visible spectrum are associated with about 42 degrees API gravity oil such as from the Jabiru oil field. Those in the yellow part of the visible spectrum, such as from the Cliff Head oil field, are associated with about 30 degrees API gravity oil.

Seismic data from the Bremer Basin, in which no exploratory wells have been drilled, indicate reservoirs in anticlines and fault blocks with potential for hundreds of millions of barrels, but the risk is that hydrocarbon charge is not proven. Samples dredged from incised canyons contain oil inclusions in low abundance indicating migratory oil. Samples from the Bremer Basin with blue fluorescence and high GOR indicate a paraffinic or mature source.

An important petroleum system in the onshore Perth Basin has a source in the basal Kockatea Shale, but there is uncertainty about its extent in the offshore basin. Calibration of the fluorescence attributes of the oil at the Cliff Head oil field, and mapping of palaeo-oil zones in reservoir intersections, showed this petroleum system was effective for oil accumulation in much of the offshore basin.

Technical Area: General – Radar and Remote Sensing