--> Abstract: Maastrichtian Heavy Oil Reservoirs in the Partitioned Neutral Zone (PNZ), Saudi Arabia and Kuwait, by W. Scott Meddaugh, Raymond A. Garber, Stewart Griest, Dennis W. Dull, and David Barge; #90072 (2007)

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Maastrichtian Heavy Oil Reservoirs in the Partitioned Neutral Zone (PNZ), Saudi Arabia and Kuwait

W. Scott Meddaugh1, Raymond A. Garber1, Stewart Griest2, Dennis W. Dull3, and David Barge4
1Chevron Energy Technology Company, Houston, TX
2Chevron Energy Technology Company, Houston, TX
3Chevron, Houston, TX
4Saudi Arabian Texaco, Houston, TX

The Maastrichtian interval (Tayarat Fm.) produces heavy oil from three fields in the PNZ – South Umm Gudair, South Fuwaris, and Wafra. These carbonate reservoirs produce high sulfur, low API gravity oil (generally 12-18° API though a portion of the Wafra reservoir produces 18-22° API oil). Most production to date has been from the Maastrichtian reservoir at Wafra field where over 50 wells have produced 32 million bbls since discovery in 1959, a small fraction of the estimated OOIP of 3 billion bbls for the Maastrichtian reservoir. Average porosity in the Wafra Maastrichtian is about 15% and the average permeability is about 100 md. Fractures may be important at Wafra field as a small number of wells have produced 4-8 million bbls. All Maastrichtian reservoirs in the PNZ are under primary production.
Within the PNZ the Maastrichtian reservoir rocks were deposited under arid shallow shelf conditions with low accommodation space that transitioned between normal marine conditions and restricted lagoonal environments. Fresh water exposure episodes were common. A recently completed PNZ-wide stratigraphic study suggests that the Maastrichtian reservoir may be better understood in terms of a large mega-structure. This study has shown that the detailed sequence stratigraphic interpretation for the Maastrichtian developed at Wafra can be extended to include the South Fuwaris and South Umm Gudair structures to the west and north, respectively as well as the Humma structure to the south. The Maastrichtian heavy oil resource potential in the PNZ may be much larger than current estimates.

 

AAPG Search and Discovery Article #90072 © 2007 AAPG and AAPG European Region Conference, Athens, Greece