Depositional Modeling of Detrital Rocks: With Emphasis on Cored Sequences of Petroleum Reservoirs

Studies of cores from both field and wildcat wells offer the opportunity to interpret subsurface rock sequences and relate them to surface sections, to calibrate mechanical logs with observed lithologies, and to use these data to enhance both field development drilling and wildcat exploration. The cored sequences of detrital rocks described in this core workshop are organized on the basis of depositional models, and presented sequentially down the depositional system through the continental environments to the shoreline zone, and, finally, to the shallow offshore and deeper water environments. Each of the depositional models is treated in separate sections in which diagrams, facies descriptions and terminology are presented that summarize the principal aspects of the model.
Alluvial Valley Environments Available to Purchase
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Published:January 01, 1985
Abstract
Deposits of the alluvial valley, controlled by the fluvial processes described in this chapter, collectively make up what is called a valley fill. In many ancient sequences, paleodrainages are incised (entrenched) into older deposits because of erosion during a lowstand of sea level. The incised valleys fill with sediment as sea level rises to the next highstand (Fig. 4.1). To interpret fully the fluvial deposits of the fill, the overall valley fill should be mapped and described in addition to the lateral and vertical changes of facies that occur within the fill. Various facies within alluvial valleys, or on coastal plains, are described in this section.
Fluvial processes also operate on coastal plains where valleys are not present. A complete understanding of a fluvial deposit is possible only when the regional depositional framework is established. For the cores in this book that are considered valley fill deposits, the regional framework of the deposit is generally known and, therefore, they are described as deposits of the valley fill processes.