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The fluid-bearing capacity of the Holocene coastal sand deposits of central South Carolina was determined in order to estimate their potential oil-in-place reservoir capacity. These sand bodies, which vary considerably in size, thickness, shape, and continuity, were deposited in a variety of depositional settings including barrier islands, tidal deltas, exposed sand flats, tidal sand ridges, and tidal point bars. Minimum potential sand thickness and conservative mud cutoff values of 10-15% were used to define each sand body type. Average thickness values ranged from 20 ft (6 m) for barrier islands to 15 ft (4.5 m) for exposed sand flats. Within the study area, barrier islands have average sand volumes of 1.3 × 105 acre-ft (1.6 × 108 m3 /SUP>), and tidal delta sands average 1.0 × 105 acre-ft (1.2 × 108 cm3).
Potential oil reserve values averaged 7 million bbl for individual barrier islands and 5 million bbl for individual ebb-tidal deltas. If the Holocene sand deposits of the central 50 mi (80 km) of the South Carolina coast were preserved in place, 150-200 million bbl of oil could be contained within the reservoir-quality sands. Of course, these values represent only one small segment of geologic time, approximately 5,000 years.
These calculations were based on typical reservoir characteristics and recovery factors found in Cretaceous sandstones buried at 5,000 ft (1,500 m) in the Rocky Mountain area. Average reservoir values used included porosity of 25%, oil saturation of 65%, formation volume factor of 1.3, and 10% of the sand body occupied by hydrocarbons.
A better understanding of these strandline sand deposits could improve exploration and future development of these significant, potentially oil-bearing sands.
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