Eromanga oil traps – a multi field post-mortem

Abstract

Summary The purpose of this paper is to examine the remaining oil potential of the Eromanga Basin, specifically in the Cooper region. The key factor is the timing of dominant oil charge. If the oil moved after the late compression and anticlinal structures are critical for commercial success, then the potential is low since almost all these features have been identified and drilled. If the oil moved before the late structuring then except for a few mappable paleostructures, the oil must have been trapped stratigraphically. The late structuring role would then tilt or remobilize the oil locally. If this is the case, then the large unexplored areas of the basin with little or no late structure are just as prospective as the explored structural areas. Additionally, even the discovered oil fields may not be fully appraised as the stratigraphic variability in reservoir has not been fully accounted for. The examination method chosen was to map and postmortem a semi-regional 9000 sq km area with 6 anticlines with numerous oil fields, near successes and dry holes. The area also has extensive 3D seismic. It was found that a strong case could be made that all the oil discoveries were stratigraphically trapped and the late structure only rearranged some of the already trapped oil. This conclusion not only upgrades the future exploration potential of the Basin but points the way to a fundamentally different way of mapping and high grading prospects.