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Fractures of the Dammam Dome Carbonate Outcrops: Their Characterization, Evolution and Implications to Deep Reservoirs

Al-Fahmi, Mohammed M.*1; Cooke, Michele 1; Cole, John 2
(1) University of Massachusetts, Amherst, MA.
(2) Reservoir Characterization, Saudi Aramco, Dhahran, Saudi Arabia.

The Tertiary carbonates of the Dammam Dome outcrops present a useful opportunity to study fractures within the oil-producing region of Saudi Arabia. The study focuses on: 1) the characterization and propagation of the outcrop fractures, 2) their potential as analogues for the deep fractured carbonate reservoirs of Dammam Dome and their equivalents in surrounding fields, and 3) the possible presence of near-surface faults that may slip in response to deep-seated salt growth of the Dome. We integrate field mapping and measurements with aerial photographs and fold curvature analysis. The fractures are observed within all exposed carbonate units, but predominantly within the Middle Rus unit due to the vast exposures of this unit. The fractures are opening-mode, bed-perpendicular joints that form orthogonal sets. Field analysis indicates that joints developed independently of the later locally-restricted karst structures. Fractures developed due to doming and their spacing is controlled by bed thickness and lithology. Faults were not found within surface outcrops, but their presence in subsurface is not precluded. The joint patterns and spacing reflect both the geometry of the doming strata, and mechanical stratigraphy. Consequently, the joint pattern can provide a first-order conceptual fracture model for the Dome carbonate reservoirs and other similar reservoirs in the region. Some of the quantitative attributes of joints (e.g. orientations, and spacing) can be integrated with the subsurface data to guide near-future reservoir development of Dammam Dome and impose probability constraints on the subsequent simulation modeling.  


AAPG Search and Discovery Article #90142 © 2012 AAPG Annual Convention and Exhibition, April 22-25, 2012, Long Beach, California