The Cretaceous Ratawi Reservoir at South Fuwaris Field, Partitioned Neutral Zone of Saudi Arabia and Kuwait: Acquisition and Interpretation of New High-Resolution 3D Seismic Data and Geological Modeling

Stewart D. Griest¹, W. Scott Meddaugh¹, John Garrity², William F. Stewart³, and Rhys Schneider^4
1Chevron Energy Technology Company, Houston, TX
²Chevron, Mina Saud, Kuwait
³Chevron Energy Technology Company, Houston, TX
⁴Chevron, Kuwait

The Lower Cretaceous Ratawi Limestone reservoir at South Fuwaris Field, discovered in 1963, is located in the Partitioned Neutral Zone (PNZ). The reservoir depth is about -5,300 feet and net reservoir intervals are approximately 100 feet thick. The field area is structurally controlled with a producing area of approximately 10,600 acres. The uppermost Ratawi Limestone contributes the majority of the production from pay intervals with average porosity of 11%, average permeability of 3.3 millidarcies, and average water saturation of 31%. The Ratawi Oolite is a minor contributor from pay intervals with average porosity of 17%, average permeability of 2.4 millidarcies, and average water saturation of 17%. Oil gravity is 25 degrees API.
New 3D seismic data were acquired, processed, and interpreted in 2005/2007 using WesternGeco Q-Land seismic technology. Increased lateral data resolution as a result of 6.25 meter spacing of single sensors in a 25 meter wide receiver line improved confidence in both structural and seismic stratigraphic interpretation of the Ratawi reservoir. Depth converted interpretations were used to build the structural framework of a geological model.
Well log data were normalized and calibrated to core data to derive consistent field-wide reservoir properties. Geostatistical modeling of porosity, permeability and water saturation was conducted. Porosity was distributed by Sequential Gaussian Simulation. Water saturation was distributed by collocated cokriging with porosity as secondary data. Permeability was distributed by layer based on a porosity/permeability transform derived from core data. Results were used to re-evaluate in-place resources and identify areas for future development drilling.

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