DownUnder package

New petroleum system models for an old but still under-explored area in Western Australia are introduced here for the very first time, namely the Vlaming Sub-Basin and a new frontier basin of the old continent, the Mentelle Basin.

The problem

There is an identified need for petroleum prediction, source rock and burial history models in the Vlaming Sub-basin and Mentelle Basin in support of proposed acreage release in 2008 and 2009, respectively. These conceptual models can be best constrained with an understanding of generation and fluid flow characteristics within the petroleum systems in the adjacent Vlaming Sub-basin. Here, proven oil and gas systems have been recognised with analogue Jurassic and older sedimentary sequences. Extrapolation of the burial history models developed in the Vlaming Sub-basin into the Mentelle Basin will provide the link between a proven petroleum system and a speculative one. There is also a need to predict the distribution and type of organic matter in source kitchens. This definition has to be in a form that can be directly trans-lated into quantitative predictions of oil and gas volumes in time and space.

The mainly offshore located Vlaming Sub-basin covers an area of approximately 23,000 km2, with water depth ranging from 0-3 km, and a sedimentary thickness of siliciclastic fluvial-deltaic and marine rocks of up to 15 km. The basin is of Permian-Cenozoic age.

• The 3D model, which covers the entire Vlaming Sub-basin, is calibrated to an extensive set of well data (temperatures, vitrinite reflectance)

The Mentelle Basin is a deepwater sedimentary basin (200-4000 m water depth), formed during the break-up of eastern Gondwana in the Middle Jurassic to Early Cretaceous. The Mentelle Basin is a frontier basin with no previous exploration history (regional seismic lines were shot in 1972). It is located on the southwest Australian continental margin to the south-west of Perth and outboard of the Vlaming Sub-basin (Bradshaw et al., 2003). The basin contains at least 5 km of marine carbonates and marine-continental siliciclastics in the deeper Western part of the basin. The strata are of Middle Jurassic to recent age.

• Three 2-D basin models were generated using the new seismic lines. It is calibrated to well data from the Vlaming Sub-basin.
• Maturity evolution for potential source rock sequences

The package

• Summary report of the approach used and main results from 2D and 3D basin modelling
• Input files of 2D and 3D PetroMod basin models in digital format. Output files available upon request
• Documentation of model definition (wells/sections/maps used, age assignment model, stratigraphic and lithologic definitions, heat flow model, paleo-waterdepth model, fault maps, etc.)
• Documentation of model calibration (1D depth plots of modelled vs. measured tempera-ture, vitrinite reflectance, porosity and pressure)
• Drainage area maps for individual carrier systems
• Burial histories of selected prospects and kitchen areas
• Maps of modelled present and past source rock maturity for individual source rock se-quences
• Masses of petroleum generated for individual drainage areas of selected prospects and individual source rocks
• Compositional predictions (including GOR, API gravity and phase state) of selected ac-cumulations