Abstract

Brittle deformation of carbonate reservoirs was characterized by applying advanced visualization and interpretation techniques to 18 recent 3-D seismic surveys in Abu Dhabi. The excellent data quality afforded a unique opportunity to integrate the broad range of observed structural styles and detailed structural geometries into a unified tectonic model. This resulted in a better and more thorough definition of the structure and hydrocarbon distribution of Abu Dhabi in the context of the entire Arabian Platform.

The observed structures resulted from gentle basement inversion, salt-tectonics, and detached thrusting. The N- and NE-trending anticlines that form the giant onshore fields grew during Late Cretaceous, basement-involved foreland inversion. Systematic sets of remarkably linear, small-offset conjugate fault zones, oriented approximately N75W and N45W, cross the antliclines at high angles to the axial traces. The consistent orientations and shear sense of the fault zones suggests they result from regional WNW-ESE compression, which also drove late Cretaceous inversion and fold growth. Development of the salt-related anticlines was influenced by the same late Cretaceous compression, as well as multiple episodes of salt movement. Both sets of anticlines share the regional fault trends, but the salt-related fault zones have more variable orientations and timing. Mechanical stratigraphy clearly influences fault zone spacing, offset, and segmentation, both laterally and vertically. Interpretations of the fault zones as single fault planes underestimate their geometric complexity. The key to unravelling and communicating the geometric complexity is making use of a combination of data optimization and advanced 3-D visualization and interpretation techniques. Quantification of the orientations, segmentation, offset magnitudes, and spacing of the fault zones provides a foundation for defining their implications for fluid flow within the reservoirs.

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