oa Arid Region Carbonate Platforms: Middle East Reservoirs

Calcitic grainstones and some dolomitic packstones are amongst the most common Middle East reservoir lithologies and they host some of the best hydrocarbon reservoirs in the world. They are well-sorted, winnowed carbonate deposits with little or no carbonate mud, normally formed in moderate to warm shallow-water, high-energy settings. Substantial accumulations of this facies may form in relatively shallow, subsiding basins so that deposition and subsidence remain in balance thus permitting continuous deposition. Where these sediments remain only partially cemented, fairly open porosity is maintained and upon burial there is only moderate compaction and such sediments can act as excellent hydrocarbon reservoirs. The packstones accumulated both downslope from the grainshoals and updip to their lea. Their porosity is in part depositional and in part diagenetic.