4D modelling of fault reactivation using complete paleostress tensors from the Cooper–Eromanga Basin, Australia

ABSTRACT

Determining fault activity through time has typically utilised high-resolution seismic data to identify stratigraphic thickness changes or displacement vs distance plots; however, this approach is not possible in regions with low-resolution seismic data. We present a new approach for determining fault reactivation (tensile and shear) through time by integrating three-dimensional seismic data, geomechanical modelling and complete paleostress tensors from calcite twin stress inversion. The Cooper–Eromanga Basin is used as a case study to model the stress conditions present during six tectonic events that have affected the basin and, in doing so, constrain the effective paleostress magnitudes through time. Results show that the likelihood of dilation and shear reactivation of individual fault sets varies through time, with N–S- and E–W-striking faults likely to have been open to fluid flow after the critical moment in the hydrocarbon system. These results have substantial implications for hydrocarbon migration pathway models and structural and stratigraphic models for the Cooper–Eromanga Basin. This approach would benefit other provinces with low-resolution seismic data preventing fault growth analysis, or in regions where hydrocarbon migration pathways are poorly defined.

KEYWORDS:

• stress
• calcite
• tectonic
• geomechanics
• structural evolution
• fault reactivation
• hydrocarbon migration
• Cooper Basin
• Eromanga Basin

Acknowledgements

DUG Insight software (v.3.1, 2015) was used for seismic visualisation, interpretation and analysis. We appreciate the feedback provided by Jozina Dirkzwager, Scott Mildren, Nicholas Direen, and the editorial team at the AJES.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The authors appreciate the financial contribution made by the GeoFrac Consortium, which includes the Program Manager Dennis Cooke, and the sponsoring companies: Santos, Beach Energy, Chevron, Halliburton and BG Group (QGC). We thank Midland Valley (MOVE 2016.2), DownUnder Geosolutions (DUG Insight) and the creators of OpenStereo 0.1.2 (Carlos H. Grohmann and Ginaldo A.C. Campanha) for their generous donation of academic licences.