Paul R. Knox
Bureau of Economic Geology
The University of Texas at Austin
Austin, Texas, U.S.A.

Mark D. Barton
Shell Development Company
Houston, Texas, U.S.A.

Early recognition of stratigraphic heterogeneity can lead to improved estimates of hydrocarbon reserves and more efficient development strategies. Although good models based on studies of modern and ancient fluvial-deltaic deposits exist for predicting interwell heterogeneity, a single model applies only to genetically related deposits of a single pulse of progradation and retreat, which describes only one, or a part of one, reservoir. Recent studies document significant changes in depositional style in adjacent stratigraphic intervals, and a model for predicting this variability is needed; therefore, we have carried out studies of outcrop reservoir analogs and of reservoirs that suggest that variability is predictable if assessed within the framework of depositional cycles and that differences between adjacent high-frequency cycles can substantially impact production behavior and reserve-growth potential.