Paleozoic sequence stratigraphy, depositional systems, and hydrocarbon habitats across the Arabian plate

Abstract

The Paleozoic sedimentary section of the Arabian plate recorded the effects of numerous fluctuations in sea level and gentle epeirogenic movements. Eustatic changes in sea level over the Arabian plate resulted in transgressions and regressions and created many local and regional unconformity surfaces, identified by missing section and nondeposition. The distant deformation of the Caledonian tectonic orogeny and mountain building of the North Atlantic region, and the later Hercynian tectonic event, are partially responsible for eustatic sea-level changes. Additionally, detailed evidence of Paleozoic glacial erosion and glacial eustasy in the regressive sedimentary section over uplifted paleohighs comes from deep wells penetrating local exotic tectonic blocks. The resulting surfaces mark the sea-level falls associated with the glacial events in the Ordovician, Late Devonian, and Carboniferous–early Permian sediments. The depositional settings of the Cambrian–upper Permian rocks include deltaic and glacial settings and are expressed as alluvial–fluvial fans that grade into braided plains and shallow-marine carbonates flanked by distal shales. Late Permian sediment fill accompanied the development of widespread accommodation, resulting from a major sea-level rise, coinciding with a major period of carbonate–evaporite deposition, in which clastic sediments were only a minor factor. The regional sedimentary facies have good reservoir quality and are juxtaposed to regional source rocks and seals associated with both structural and minor stratigraphic traps. Production occurs in Precambrian through Permian strata in which mature clastic and shallow-water carbonate reservoirs occur, commonly sealed by shales, and sourced by Silurian hot shales or older source rocks in the section.