--> Abstract: The Wafra First Eocene Reservoir in the Partitioned Neutral Zone (PNZ), Saudi Arabia and Kuwait: Geology and Reservoir Modeling for the Large Scale Steamflood Pilot, by W. Scott Meddaugh, Kera Gautreau, Niall Toomey, and Stewart Griest; #90077 (2008)

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The Wafra First Eocene Reservoir in the Partitioned Neutral Zone (PNZ), Saudi Arabia and Kuwait: Geology and Reservoir Modeling for the Large Scale Steamflood Pilot

W. Scott Meddaugh*, Kera Gautreau, Niall Toomey, and Stewart Griest
Chevron, USA
*[email protected]

The Eocene-Paleocene First Eocene reservoir at Wafra field was discovered in 1954 and has produced about 300 million barrels of 17-19° API, high sulfur oil. The estimated original-oil-in-place for the reservoir is 9 to 12 billion barrels. The reservoir is mainly composed of pervasively dolomitized packstones and grainstones with minor mudstone and anhydrite/gypsum. The sediments were deposited in shallow water on a gently dipping, low-energy inner-shelf or ramp under arid to semi-arid conditions. The reservoir average porosity is 35% and the average permeability is 250 mD. Individual core-plug measurements range up to 50% porosity and 5,000 mD permeability. The large scale steamflood pilot (LSP) consists of 16 inverted 5-spot patterns covering 40 acres. A total of 60 wells are in the LSP area, 56 of which were drilled in 2007 (including four cores) affording an unprecedented opportunity to quantitatively assess and model the reservoir at a small scale. To support early reservoir development decisions, a detailed geostatistical model was generated using a 5 m areal cell size. The well-based data is supplemented by a recently acquired high-resolution 3-D seismic volume and historical production data. Geostatistical analysis yielded semivariogram models with an areal (XY) range parameter of 200-900 m and a vertical (Z) range parameter of 0.3–0.8 m. While these values are substantially less than those reported for a prior full-field study using wells largely drilled on a 500-1,000 m spacing, the range parameters are several times the average well spacing in the LSP.

 

AAPG Search and Discovery Article #90077©2008 GEO 2008 Middle East Conference and Exhibition, Manama, Bahrain