Published:January 01, 1980
Deltaic depositional facies result from interacting dynamic physical processes (wave energy, tidal action, climate, etc.) which modify and disperse riverborne elastics. Since ancient times, river deltas have been of fundamental importance to civilization. Owing to their early significance as agricultural lands, deltas received considerable attention from scholars such as Homer, Herodotus, Plato, and Aristotle. More recently, subsurface deltaic facies have played a paramount role in accommodating the world's energy needs; ancient deltaic sediments have provided source beds and reservoirs for a large percentage of the known petroleum reserves. The facies relationships and mechanisms responsible for development and distribution of deltaic sand bodies must be understood before they can be explored efficiently.
Deltaic environmental settings normally exhibit many of the characteristics required of a potential hydrocarbon-producing basin—multiple types of reservoir rocks, immediate or nearby source beds, a wide variety of structural and stratigraphic traps, and a buildup of considerable thickness of clastic rocks that are rapidly varied.
This short course will cover three major aspects of deltaic sediments: (a) the main processes responsible for the formation of sand bodies; (b) the sedimentary characteristics of the deposits (both sub aerial and subaqueous delta sequences); and (c) the variability of delta sediments that are deposited under a wide range of depositional facies. The modern Mississippi River will be used to illustrate the first two aspects. A considerable amount of subsurface data is available, and a large number of process studies provide the basis for this portion of the course. The discussion of the
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Deltaic Sand Bodies
The publication features a broad treatment of the depositional aspects of deltas, including regional settings, process activity, and their role in sedimentation. Sedimentation patterns and sand distribution in models are discussed. Examples are taken from around the world and ancient analogs are offered. An emphasis is placed on the exploration for hydrocarbons in a deltaic environment.