Halokinesis Stimuluses on Petroleum System of Abu Dhabi

Abstract

Halokinesis has strongly stimuluses the Abu Dhabi petroleum system. During the Late Precambrian, the basement terranes of the Arabian and adjoining plates were fused along the northeastern margin of the African Gondwanaland plate. This phase was followed by continental rifting and intra-continental extension. The Arabian Infracambrian extensional system established rifted salt basins in the Zagros region, South Oman and in the Arabian Gulf. The Hormuz salt in these areas contains basalt and rhyolite, suggesting tectonic extension at this time. The Zagros thrust fault and Dibba transform fault define the current limits of the Hormuz Complex of the Arabian Gulf. As a passive margin during Paleozoic time, the Arabian plate accumulated a continentally influenced shallow marine sequence characterized by interbedded siltstones, sandstones, shales and carbonates sediments. The Late Ordovician-Early Silurian glaciation interrupted the Paleozoic deposition by lowering sea level in the Late Silurian and Late Carboniferous-Early Permian glaciation. Salt movement was started an extensional phase in Permo-Jurassic with the Neo-Tethys opening and basement faults reactivation. Followed by Cretaceous compression stress due to Afro-Arabian Plate movement. The third phase happened by Late Cretaceous with the closing of the Neo-Tethys. The salt was finally pierced to the surface by Mid Tertiary compression stress forces accompanied with Oman thrusting and Zagros folding. Since Miocene uplift, the salt movement extended until present day onwards. Previously, the pierced salt was considered stacked, but subsidence measurements indicating salt is still moving in some islands reaching about 2cm per year. This paper uses 3D seismic, core data and outcrops investigations to assess the geometry, kinematics, and the halokinetic phases that stimuluses the hydrocarbon exploration targets. The paper revisited the flowage phases of the salt in Abu Dhabi, investigated the accompanying fault geometries and relate this to the structural styles. The diapiric anticlines forming during salt movement phases forming domal structures with radial faults. Contradicting what is known, the Miocene-recent strata are tilted indicating the continuation of the salt movement. The Hormuz salt is characterized by a regionally consistent stratigraphy, formed of evaporites interbedded with clastic and carbonate sediments with dolomite intervals and vein intrusions of volcanic rocks. Interpreted faults were categorized into three families, Type I comprising domal radial faults, Type II representing faults triggered salt movements and Type III describing salt movements triggered faults. The first type is characterizing itself by its location relative to the crystal parts of the domes. The relatively low overburden pressure at the crest of the diapir and the original high dip angles of these fault planes favor salt intrusions near the diapir crest. Depending on the salt movement phases, the generated cycles of these faults, are characterized by different dips and areas of extension, while the other two categories can be differentiated as well. At the time of salt movement initiation, these faults were incipiently intruded by salt for relieving the intense internal overpressure in the salt body. These pressures are due to the compression forces associated with the salt movement, the buoyancy effects compensating the density difference between salt and overlying sediments and the tectonic compression forces. The latter is the reasonable mechanisms that allow salt penetration along fault planes and bedding planes. This paper provides evidences that salt movements impact the petroleum system, especially traps, as if the salt movement preceding the hydrocarbon migration, this leads to faults sealing and the reverse is also applied.