Sensitivity Analysis for 2D Modelling, Duntroon Basin, South Australia

Barry E. Messent and Bjorn Wyralia

The Duntroon Basin is a passive-margin, frontier basin off the southern coastline of Australia. Six wells have so far been drilled in the basin with no recovery of hydrocarbons to surface.

Using PETROMOD, a 2D migration-modelling package with three- phase flow (including a three-phase/gas diffusion flow simulator), a sensitivity analysis was carried out to understand more clearly the prospective petroleum system in the basin. Initial modelling of a seismic line close to a well provided calibration of thermal and pressure data.

The following variables and the resulting effects were investigated in the study:

Variations of up to 500 m in the depth of the source interval in the Outer Basin, resulting from mispicking or depth-conversion errors; Variations in the heat-flow history within the limits defined by the calibration data; Distortions of present and paleo-temperatures by aquifer systems; Variations in the kinetic models used to determine hydrocarbon generation; Variations in source rock properties (TOC and HI values); Changing fault properties.

The relative importance of these variables on the timing and pattern of hydrocarbon generation, expulsion, migration and resulting accumulations, as well as their relationship to the structural development of the basin, is examined.

AAPG Search and Discover Article #91019©1996 AAPG Convention and Exhibition 19-22 May 1996, San Diego, California