Evaluating Fault Seal Behavior and Reservoir Compartmentalization with Dynamic Reservoir Data and Oil Geochemistry from Takula Field, Offshore Cabinda, Angola

Wesley Combs¹, Paulo Bernardo¹, Padmanabhan Sundararaman¹, Carlos Canje¹, and David B. Rains^2
1Cabinda Gulf Oil Company, Chevron, Luanda, Angola
²Chevron International Exploration and Production, Chevron, Houston, TX

The Takula Field is a rollover anticline pierced by crestal compensation faults and antithetic faults at the Cretaceous Vermelha reservoir interval. Understanding the sealing nature of these faults is critical to waterflood management and further development planning of this 2.2 BBO reservoir.

Seismic interpretation identifies a series of short discontinuous faults that do not clearly divide the reservoir into distinct fault compartments. There is a lack of accuracy in positioning of sands against the faults relative to individual sand thicknesses of 10 - 15 meters and fault throw ranges of 5 - 15 meters. Consequently there is a good deal of uncertainty in Allan mapping and SGR calculations as reliable tools for predicting fault behavior.

To assess whether the faults seal, leak, or act as baffles to fluid flow we look beyond the static properties of the faults. Examination of dynamic reservoir fluid properties leads to better understanding of fault seal capacity. Mapping and interpretation of fluid saturations and pressures in individual sand layers indicate possible sealing faults. Oil geochemistry analysis provides insight into possible fault compartmentalization of the reservoir.

AAPG International Conference and Exhibition, Cape Town, South Africa 2008 © AAPG Search and Discovery