Print this pageAAPG GEO 2010 Middle East
Geoscience Conference & Exhibition
Innovative Geoscience Solutions – Meeting Hydrocarbon Demand in Changing Times
March 7-10, 2010 – Manama, Bahrain
Early and Charge Related Diagenetic Controls from Rock Types (Arab C and D Reservoirs, South Rub' Al Khali Basin, Saudi Arabia)
(1) Shell International Exploration & Production, The Hague, Netherlands.
(2) South Rub Al Khali Company Ltd, Al-Khobar, Saudi Arabia.
The South Rub ‘al Khali Company Ltd (SRAK) is an Incorporated Joint Venture between Shell Saudi Ventures Limited (50%) and Saudi Arabian Oil Company (50%) and was set up in order to explore for non-associated gas in the South Rub ‘al Khali Basin as part of the Natural Gas Initiative in the Kingdom of Saudi Arabia.
The Arab C and D reservoirs in the Kidan Field of the South Rub ’al Khali Basin have recently been the targets of a well drilled by the SRAK Venture. A total of 350 ft continuous core was obtained to characterize reservoir properties and interpret key processes controlling their distribution across the field. Depositional environments and early diagenetic patterns provided the template for burial and charge-related modification of rock properties. Distinct reservoir rock types have been differentiated based on petrographic observations, core porosity, core permeability and MICP (mercury injection capillary pressure) data.
This presentation focuses on the results of the detailed diagenetic and geochemical study that allows the interpretation of the key processes controlling the differentiated rock types in Arab C dolostone units and Arab D ooid grainstone units. Dolostone reservoir properties in the Arab C are mainly controlled by the presence/absence of late calcite and / or late anhydrite plugging of intercrystalline porosity. The key diagenetic processes recorded in rock types from Arab D grainstones are: early cementation, compaction, burial cementation (including calcite, fluorite and anhydrite), late leaching and late charge-related cementation (calcite and saddle dolomite).
The rock types are mostly stratigraphically defined units, in spite of the recorded complexity of diagenetic processes, associated diagenetic products and pore size distributions. The stratigraphic arrangement of the rock types in the studied core responds to depositional and early diagenetic controls. The late diagenetic products follow the early diagenetic template, nevertheless understanding the impact of late diagenesis has proven key to predict the rock properties across the field and construct new reservoir models.