Secondary pores in carbonate reservoirs on Arabian Peninsula
Nearly all of the giant carbonate reservoirs on the Arabian Peninsula have both primary and secondary pore systems. There are, however, significant stratigraphic and geographic variations of origin, volume, and reservoir importance of secondary pores. The Permian Khuff reservoir zones generally has more secondary porosity than any younger, or shallower, reservoir formations. Highly permeable idiotopic (sucrosic) dolomites are commonly developed in zones which originally contained primary pores. The zones with the highest porosity often contain secondary pores, with calcite-free oomoldic dolomites having higher permeability than oomoldic limestones. Fractures resulting from halokinetics and/or salt dissolution are generally the most important secondary pores in Khuff reservoirs. The prolific Jurassic Arab reservoir zones, generally have lesser amounts of secondary pores than Khuff reservoirs, but a variety of secondary pores are present. Commonly the Arab C zone contains the greatest volume of secondary pores, generally of a moldic (grain and/or skeletal) nature. Secondary porosity associated with dolomitization is regionally more common in the eastern Gulf. Cretaceous (rudist) reefal and chalk reservoirs often contain zones of secondary porosity with enhanced permeability resulting from the leaching of aragonitic and high-magnesium calcite skeletal material. Secondary porosity is present in the western gulf in both the Minagish grainstones and dolomitized Shuaiba Formation, whereas the grainstones of the eastern gulf have little secondary porosity. Large fracture systems are present everywhere in low-permeability chalks and wackestones. An unusually high degree of porosity heterogeneity appears to be ubiquitous in Cretaceous sequences.
- Research Organization:
- Schlumberger Technical Services, Dubai, United Arab Emirates
- OSTI ID:
- 6001306
- Report Number(s):
- CONF-870606-
- Journal Information:
- AAPG (Am. Assoc. Pet. Geol.) Bull.; (United States), Vol. 71:5; Conference: American Association of Petroleum Geologists annual meeting, Los Angeles, CA, USA, 7 Jun 1987
- Country of Publication:
- United States
- Language:
- English
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