About This Item

Share This Item

The AAPG/Datapages Combined Publications Database

AAPG Special Volumes


P. Boult and J. Kaldi, eds., 2005, Evaluating fault and cap rock seals: AAPG Hedberg Series, no. 2, p. 73-85.


Copyright copy2005 by The American Association of Petroleum Geologists.

FAST: A New Technique for Geomechanical Assessment of the Risk of Reactivation-related Breach of Fault Seals

Scott D. Mildren,1 Richard R. Hillis,2 Paul J. Lyon,2 Jeremy J. Meyer,1 David N. Dewhurst,3 Peter J. Boult4

1Australian Petroleum Cooperative Research Center, Australian School of Petroleum, University of Adelaide, Australia; Present address: JRS Petroleum Research, Adelaide, Australia
2Australian Petroleum Cooperative Research Center, Australian School of Petroleum, University of Adelaide, Australia
3Australian Petroleum Cooperative Research Center, Commonwealth Scientific and Industrial Research Organization Petroleum, Australian Resources Research Center, Perth, Western Australia
4Australian School of Petroleum, University of Adelaide, Australia and also Department of Primary Industries and Resources South Australia, Adelaide, Australia


Postcharge fault reactivation may cause fault seal breach. We present a new methodology for assessment of the risk of reactivation-related seal breach: fault analysis seal technology (FAST). The methodology is based on the brittle failure theory and, unlike other geomechanical methods, recognizes that faults may show significant cohesive strength. The likelihood of fault reactivation, which is expressed by the increase in pore pressure (DeltaP) necessary for fault to reactivate, can be determined given the knowledge of the in-situ stress field, fault rock failure envelope, pore pressure, and fault geometry. The FAST methodology was applied to the fault-bound Zema structure in the Otway Basin, South Australia. Analysis of juxtaposition and fault deformation processes indicated that the fault was likely to be sealing, but the structure was found to contain a residual hydrocarbon column. The FAST analysis indicates that segments of the fault are optimally oriented for reactivation in the in-situ stress field. Microstructural evidence of open fractures in a fault zone in the subsurface in an offset well and an SP (self-potential) anomaly associated with a subseismic fault cutting the regional seal in the Zema-1 well support the interpretation that seal breach is related to fracturing.

Pay-Per-View Purchase Options

The article is available through a document delivery service. Explain these Purchase Options.

Watermarked PDF Document: $14
Open PDF Document: $24