Basement-cover reservoir analogue in rift-margin fault blocks; Gulf of Suez Rift, Sinai, Egypt

摘要

Faults, fracture systems, weathering profiles and cover sediments of granitic basement in the rift shoulder of the Gulf of Suez Rift (Sinai, Egypt) are useful conceptual analogues for basement-cover reservoir fields. Outcrops demonstrate that fracture intensity peaks adjacent to major faults, and declines in damage zones that stretch to the background fracturing level over distances of 150 m. In the rift shoulder, smaller faults have damage zones that are 30 - 40 m wide with 1 - 5 m-wide fracture corridors. Faults show chemical alteration extending hundreds of metres into basement, with characteristics similar to saprolite in schists, mafic rocks and granitoids. Cover sandstones fill and drape top-basement relief, as recorded by metre-thick basal fluvial coarse sandstones, hosting kaolinite both as diagenetic pore fill and clastic grains. Overlying floodplain to marginal-marine deposits consist of mature quartz arenites.