ABSTRACT: Contemporary stress orientation and structural permeability in the Petrel Sub-basin
Mildren, Scott D.1, Richard R. Hillis2,
and Richard
Jones3
(1) National Centre for Petroleum Geology and Geophysics, South
Australia, Australia
(2) Adelaide University, Adelaide, Australia
(3) National Centre for
Petroleum Geology and Geophysics, University of Adelaide, Adelaide, Australia
Four-arm dipmeter logs from six wells in the Petrel Sub-basin (southern Bonaparte Basin) were interpreted for borehole breakouts. Results of the analysis reveal a consistent NE-SW contemporary SHmax orientation (055°N). This orientation is parallel to the average SHmax determined further north in the Timor Sea area (northern Bonaparte Basin) and the adjacent onshore Canning Basin. The data supports the interpretation that the NE-SW SHmax direction in the area reflects a first-order stress pattern controlled by plate boundary forces along the northeastern margin of the Indo-Australian Plate. Numerical modelling of the stress field in response to plate boundary forces suggests that the divergence of SHmax from a plate motion parallel direction can be explained by the heterogeneous nature of the northeastern plate boundary.
A new fault-seal
integrity rapid evaluation tool has been developed to integrate the
contemporary stress field with structural information to produce a structural permeability
risk map. Fault-
seal
integrity is colour mapped along fault strike according to
orientation and dip for a given stratigraphic horizon. This technique has been applied to
the Petrel Sub-basin using the newly interpreted stress orientations and stress magnitude
estimates. The dominant NW-SE structural grain of the sub-basin has a relatively low risk
of
seal
breach with respect to the development of structural permeability within the
contemporary stress field. However, changes in dip along fault strike do significantly
vary the risk of failure and therefore it is critical to undertake the assessment using 3D
stress and fault orientation data.
AAPG Search and Discovery Article #90913©2000 AAPG International Conference and Exhibition, Bali, Indonesia