Influence of Depositional Fabric, Diagenesis and Structural Controls on Arab D Oil Production, Ghawar Field, Saudi Arabia

By

 Thomas H. Keith¹, D.L. Cantrell², P.D. LaCroix², Ed Clerk², H. M. Daify², P.K. Swart³, C.R. Handford⁴, I. Oskaya⁵

(1) Saudi Aramco, Dhahran, Saudi Arabia (2) Saudi Aramco, (3) University of Miami, (4) Strata-Search,LLC, (5) Baker Hughes,

 Ghawar Arab-D production behavior is the result of a complex interaction of geological processes. Depositional, diagenetic, and structural events occurring through geologic time have produced a pattern of porosity and permeability which is sometimes dominated by one factor but, more often is the result of the interaction of all three elements. It is the lack of recognition of the interaction of primary depositional fabrics, different dolomite textures, and fractures on a wide variety of scales and characteristics which has made many production phenomena difficult to explain in the past.

New technologies employed at Saudi Aramco as well as new, integrated work flows which have emerged within the past 10 years have contributed to a quantum leap in our understanding of this behavior and our ability to predict reservoir architecture and its resulting flow patterns. Sequence stratigraphic analysis of depositional processes has significantly improved our ability to predict original rock textures and their permeability between wells. Recent isotope studies have suggested a complex history of diagenesis resulting in predictable reservoir parameters and distributions for different types of dolomite. 3D seismic surveys, image logging and geomechanical studies have given us a detailed picture of fractures ranging from the micro to the macro scale.

Examples of production dominated by each of these processes are shown along with their characteristics. Key studies devoted to sequence stratigraphy, diagenesis, and fracture distribution are summarized and examples of their impact on production patterns are illustrated. Also shown are areas in which all three fundamental aspects of reservoir architecture must be invoked in order to understand and predict reservoir performance.