Geology and Production Significance of Dolomite, Arab-D Reservoir, Ghawar Field, Saudi Arabia
GeoArabia, Vol. 6, No. 1, 2001 Gulf PetroLink, Bahrain Arab-D Reservoir, Ghawar Field, Saudi Arbia Geology and Production Significance of Dolomite, Arab-D Reservoir, Ghawar Field, Saudi Arabia David L. Cantrell, Saudi Aramco, Peter K. Swart, University of Miami, Robertson C. Handford, Consultant, Christopher G. Kendall, University of South Carolina, and Hildegard Westphal, University of Hannover ABSTRACT At least five distinct types of dolomite occur in the Arab-D Reservoir in Ghawar field, Saudi Arabia – one of which appears to be responsible for high flow or ‘super-k’. These dolomite types are distinct petrographically, geochemically and stratigraphically: • a finely-crystalline non-fabric-preserving (NFP) variety of dolomite in the lower Arab- D (Zone 3) with low oxygen isotope values and generally poor reservoir quality; • a medium-crystalline NFP dolomite with high oxygen isotope values and very poor reservoir quality in the upper Arab-D (Zone 2); • a medium to coarsely-crystalline NFP dolomite with low oxygen isotopic values and very good reservoir quality (‘super-k’) occurring in Zone 2; and • a finely-crystalline fabric-preserving (FP) dolomite in the uppermost Arab-D (Zone 1) that contains high oxygen isotope values and has generally fair to poor reservoir quality. Previous studies have documented a rare fifth type of dolomite, baroque or ‘saddle’ dolomite, that occurs locally in the reservoir as well. This study also quantified and mapped the abundance and distribution of dolomite across the field, using all available core and log data. Analysis of dolomite distribution map patterns reveals that dolomite occurs in Ghawar as a series of linear trends extending for tens’s of kilometers.
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