FRACTURES OF THE DAMMAM DOME CARBONATE OUTCROPS: THEIR CHARACTERIZATION, EVOLUTION, AND POTENTIAL AS RESERVOIR ANALOGUES

The Tertiary carbonates of the Dammam Dome present a useful opportunity to study fractures in outcrops within the oil-producing region of Saudi Arabia. The study focuses on: 1) the characterization and interpretation of the outcrop fractures, 2) their potential as analogues for the deep 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. I integrate field mapping and measurements with analysis of fractures from aerial photographs and fold curvature. The fractures are observed within all exposed carbonate units, but predominantly within the widely exposed Middle Rus 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 interpreted to have 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 produce probability constraints on the subsequent simulation modeling.