Enhancement of OIP Through Reservoir Modeling of a Multi-Layered Siliciclastic Reservoir: A Case Study from Muglad Basin, Sudan

Ahmed A. Mohammed, Sr.* and Fadul A. Ahmed, Sr.
GNOPC, Sudan
*[email protected]

Toma South field is located in Block 1A of the Greater Nile Petroleum Operating Company (GNPOC) concession area, in the Muglad Basin, Sudan. The trap is a structural closure located on a tilted up-thrown side of a normal fault block. The trapping mechanism is a combination of fault and dip closure. Most faults in this structure approximately trend NW. One exception is a small normal fault that is oriented almost perpendicular to the major fault that divides the field into two parts. The main reservoir is the Early Cretaceous Bentiu sand. The Aradeiba main sand (Late Cretaceous) is a secondary oil accumulation. Both are layered sand reservoirs with continuous barriers between these layers over a large area in the field. Production started in 1999, and as of 2005 cumulative production was 112 million stock tank barrels (MMSTB). Both PCP and ESP are used, however, a rapid increase in water cut was experienced in this field, which affected oil production. Accordingly GNPOC out-sourced a full-field study to Research Institute of Petroleum Exploration Development (RIPED), Beijing, China. Geoframe^TM and Petrel^TM software were used to develop the fault/structure and 3-D geological model of the field. In addition a seismic inversion study was undertaken to develop fault and structural models. A facies model was built from the 3-D seismic cube using seismic attributes. A facies and property model was built for all the cells of the 3-D geological model. After remodeling and the identification of the architecture of the sand bodies, the extent the oil-in-place was recalculated resulting in a 21.8% increase in original-oil-in-place and a 37.4% increase in the estimated ultimate recoverable reserves.

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