--> Abstract: Improving Seismic Interpretations Of Normal Fault Geometries With Dislocation Models, by S. S. Young, D. D. Pollard, R. K. Davies, D. L. Van Nostrand, and R. W. Krantz; #90928 (1999).

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YOUNG, S. S.1, D. D. POLLARD1, R. K. DAVIES2, D. L. VAN NOSTRAND3, and R. W. KRANTZ3
1Stanford Rock Fracture Project, Stanford University, CA
2ARCO Exploration and Production Tech., Plano, TX
3ARCO Alaska, Anchorage, AK

Abstract: Improving Seismic Interpretations of Normal Fault Geometries with Dislocation Models

To reduce the uncertainty associated with interpreting fault geometries in 3D seismic data, we use numerical models to reproduce the displacement fields around a set of faults interpreted in a 3D seismic data set from Prudhoe Bay, Alaska. The 3D seismic data, along with log data from producing wells provide good constraints on fault geometry, slip distribution, and the geometry of sedimentary horizons near the upper terminations of the faults. However, at greater depths, interpretations become increasingly more subjective due to stratigraphic heterogeneity and decreasing data quality. Consequently, the depth of a horizon near a fault may be poorly constrained except where a well penetrates the given horizon. To address this problem displacement fields are computed with Poly3D, a 3D boundary element code that uses angular dislocations to approximate faults in an elastic half space. Vertical displacement fields on horizontal sections are used to construct synthetic structure contour maps, which are compared to structure contours interpreted from seismic data. Parameters that affect the modeled displacement fields include fault geometry and slip distributions. Refinements to the original fault geometries are made by varying these parameters until the synthetic structure contour map is sufficiently close to the interpreted map. The imposed boundary conditions take into account the tectonic history of the region, in particular the depth of faulting and the regional strain orientation. The results from this study indicate that dislocation models are an effective tool for improving seismic interpretations of normal faults.

AAPG Search and Discovery Article #90928©1999 AAPG Annual Convention, San Antonio, Texas