Production Attribute Mapping Workflow to Assess Remaining Resource Potential and Distribution of Water in the First Eocene Reservoir at Wafra Field, Partitioned Neutral Zone, Saudi Arabia and Kuwait

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

The First Eocene reservoir at Wafra field was discovered in 1954 and has produced about 290 million barrels of 17-19o API, high sulfur oil. The estimated oil-originally-in-place exceeds 9 billion barrels. Previous studies, which have relied on static data, were not able to quantitatively predict water-cut and water-saturation trends within this reservoir. A production attribute mapping workflow was developed that incorporated static and dynamic data. The workflow has been used to define the current distribution of oil and water within the reservoir and provide an estimate of remaining hydrocarbons in-place (RHIP) by area and stratigraphic layer. Estimation of RHIP utilizes a workflow in which full-field saturation maps representing reservoir conditions at the end of 2006 are generated using production attribute mapping techniques. The saturation map is combined with original net pay porosity-thickness values to generate a map of RHIP. Defining the current distribution of water within the reservoir is a complex task due to the long production history and large number of wells in the reservoir. A workflow was developed to map water-cut through time, with a focus on the earliest producers in the reservoir. Preliminary results suggested that the waterfronts initially move primarily from the north and south in structurally low areas. After about 12 months, the waterfronts begin to converge and appear to fully converge within about 120 months. Migration from the southwest may not be related to structure, but may be influenced by facies distribution. Results from the production attribute workflow will be used as part of on-going reservoir management decisions as well as to update current static and dynamic reservoir models.

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