Hydrocarbon Exploration and Production Potential of the Gulf of Suez Basin in the Framework of the New Tectonostratigraphic Model

Abstract

The Gulf of Suez Basin (GOS), a World Class Hydrocarbon Province, is a typical Continental Rift, but many perplexities arise from the different proposed evolutionary models. Previous models described extension along (N)NW-(S)SE faults generating antithetic half grabens, but these models show numerous difficulties and are not able to capture all observed elements into one single frame, as the reconstructions are hampered by low seismic resolution below the heterogeneous Upper Miocene salt. Our analyses (from outcrop, seismic, well logs, gravimetry, magnetometry, dipmeter, and seismic and magnetic reprocessing), performed over the last years, allows the definition of a new tectonic model better describing these features: The GOS evolution is placed in a sinistral transtensional regime, reinterpreting the Duwi (WNW-ESE), Clysmic (NW-SE), Aqaba (NNE-SSW), and Cross (NE-SW) trends and the two (twist) accommodation zones, showing two distinct episodes resulting in overprinting of differently trending and tilting fault blocks. Furthermore, it tackles perplexities related to the link between subsidence amounts/rates (backstripping), and extension, strain distribution, and episodes/pulses/unconformities. It describes the increase in extension towards the south in the rift-sphenochasm and resolves the enigmatic relationship between high angle faults (that dominate the area), low angle dipping older faults and rotated pre-rift successions. Our model foresees a two staged evolution: Initial rifting (Early Miocene - E1; Abu Zenima, Nukhul, Rudeis series) occurred along WNW-ESE trending (Duwi) faults disposed in an en-echelon manner as a result of a sinistral transtension. These faults progressively rotated in some areas towards a low angle with accompanied high angle "antithetic" tilted pre-rift strata. Subsidence accelerated during the Early Miocene, and some of these tilted fault blocks show erosion surfaces partly related to the final Early Miocene tectonic pulse. In a second stage (Mio- Pliocene - E2; Kareem, Belayim series, South Garib salt, Zeit evaporates) this pattern is overprinted by a new set of high angle rift faults trending (N)NW-(S)SE (Clysmic) cross-cutting the previous faults, but without any major block rotation. The Late Pliocene-Pleistocene (E3; Post Zeit, Shulher series) large (accelerating) differential uplift and subsidence, shows "synthetic tilting" of the strata along the rift margins, local tectonic inversions in different episodes, syn- sedimentary detachment along the mobile salt layer with the generation of en-echelon ridges, generating the present day complex fault pattern (sigmoidal intervening trends and cross trends), and differently tilted smaller fault blocks. The new model is fully compatible with the pulsating NNE-NE movement of the Sinai Plate, associated with the NE moving Arabian Plate and Red Sea rifting, and has severe consequences for further Exploration and Development in the GOS, as it describes the configuration of the Hydrocarbon Fields in a more comprehensive way and predicts the occurrences of undiscovered Prospects.