Tectonic Fractures Analysis of the South Fuwaris Field in the Kuwait-Saudi Arabia Partitioned Neutral Zone

By

 Dr. Osama Amin Al-Shaarawy¹, Pablo R. Vera², Falah M. Al-Yami³

(1) Kuwait oil Company & Saudi Arabian Texaco, Ahmadi, Kuwait (2) Cheveron-Texaco, (3) Saudi Arabian Texaco (SAT), Ahmadi,

 The South Fuwaris Field anticlinal structure is located in the southwestern part of the Partitioned Neutral Zone between Kuwait and Saudi Arabia. An oriented core fracture analysis integrated 3-D seismic attribute maps with geology, rock properties, pressure, and production data were used to investigate the nature, orientation, and geometry of the reservoir fractures. The study showed the presence of open fractures in the Lower Cretaceous carbonate reservoir. The FMI analyses of vertical and horizontal wells were used to verify the open fracture orientation. The in-situ stress was confirmed from the induced fracture orientation.

The kinematic analysis of the South Fuwaris structure indicated that compressional stress was responsible for creating the main axis of the structural culmination and the induced fractures, whereas an extensional stress created the open fractures. The dynamic analysis indicated that the main axis of the anticlinorium, together with the induced and the extensional fractures are caused by a right-lateral shear couple. This simple shear tectonic model with compressional and extensional components was responsible for producing similar Cretaceous tectonic trends elsewhere in the region. Structural deformation probably occurred throughout the Early Cretaceous.

By using this model, a better understanding of the fracture system of the South Fuwaris was obtained. The new information was in turn used to design the horizontal trajectory of two South Fuwaris wells. Encouraging results were obtained for both wells. The field is currently undergoing a reservoir evaluation aimed at designing an optimum depletion strategy. It is expected that the exploitation and development plan will include the drilling of several horizontal wells. The application of the tectonic model described here will have a direct impact on the design of the horizontal well trajectories.