The Middle and Late Jurassic Intrashelf Basin of the Eastern Arabian Peninsula
CONTAINS OPEN ACCESS
This Memoir provides a thorough regional synthesis of the geology of the rimmed Arabian Intrashelf Basin, reconciling differing interpretations of lithostratigraphy, sequence stratigraphy and biostratigraphy. Variation of energy levels and facies due to its setting in the SE palaeotradewind belt are described. The intrashelf basin formed during rising sea level as a single rimmed carbonate intrashelf basin. A possible global cooling phase resulted in a lowstand which restricted the basin, resulting in petrographically unique carbonate source rock facies dominated by cyanobacterial deposition. Two subsequent third-order carbonate sequences largely filled the basin. Eustatic change concomitant with uplift of the Tethys shelf resulted in alternation of carbonates and evaporites (gypsum-anhydrite) across the region. The end result was a sealed intrashelf basin which preserved early formed porosity and confined generated hydrocarbons within the intrashelf basin facies.
Chapter 7 Exploration implications
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Published:November 16, 2020
Abstract
Exploration of the Jurassic hydrocarbon system in the Arabian Intrashelf Basin area is in a mature state. Given the scale of the present day anticlinal structures and the adjacent synclines, all of the supergiant conventional fields trapped in huge anticlines have already been discovered. The theme throughout this Memoir has been to present the evolution of the self-contained Callovian–Tithonian Arabian Intrashelf Basin hydrocarbon system. Its size, c. 1200 × 450 km, is greater than that of the UK, larger than the Black Sea and almost as large as Turkey or the area of Texas and New Mexico in the USA. It is geologically much simpler than these regions, both in the exceptionally remarkable continuity of facies within the sequences that developed and filled the intrashelf basin and its relative tectonic simplicity, including up to the present day. The cross-sections, facies maps, depositional profiles and other data and interpretations presented in this Memoir have documented this remarkable continuity. The source rock interval is well-defined everywhere it occurs and is mature; enough oil has been generated and migrated so that every sealed trap with reservoir facies will have oil. Around and within the basin, shallow water ramp facies in each sequence are in the reservoir facies and the early-formed porosity has been preserved. The carbonate seals and, even more so, the evaporite seals are remarkably laterally continuous. Therefore the big issue in future exploration is finding a sealed trap with potential reserves large enough to be worth drilling when compared to known reserves and estimates of future production. This chapter discusses some possibilities for stratigraphic traps and unconventional plays. Potential plays have been and/or can be identified, but finding them in the present day structural setting is likely to be very difficult.
- Abu Dhabi
- anhydrite
- anticlines
- Arabian Peninsula
- Asia
- Bajocian
- Callovian
- carbonate ramps
- carbonate rocks
- Cretaceous
- folds
- giant fields
- grainstone
- Hanifa Formation
- Jurassic
- lithofacies
- maturity
- Mesozoic
- Middle Jurassic
- oil and gas fields
- petroleum
- petroleum exploration
- porosity
- reservoir properties
- Saudi Arabia
- sealing
- sedimentary rocks
- source rocks
- stratigraphic traps
- structural controls
- sulfates
- Tithonian
- traps
- United Arab Emirates
- Upper Jurassic
- Dhruma Formation
- Marrat Formation
- Rayda Formation
- Gotnia Basin
- Arabian intrashelf basin