Geophysical logs are a primary means for interpretation of sedimentology and stratigraphy of subsurface aquifers and reservoirs. This contribution by Farrell et al. illustrates the techniques and application of a process-based method of graphic logging and stratigraphic interpretation, independent from composition, cementation, and geologic environment. The utility of this texturally-based classification of clastic sediment is evidenced by four examples of shelf to shoreface successions, including steps of identifying rock units (facies) independent of composition, and interpreting environments, facies associations, boundaries and systems tracts. In these successions, gamma logs indicate grain size and spikes in radiation are associated with coarse lags at sequence boundaries, not high mud content. This process-based technique, interpreted to integrate facies analysis and sequence stratigraphy, should be broadly applicable to capturing and interpreting heterogeneity in reservoir or aquifer quality in subsurface systems.
Graphic logging for interpreting process-generated stratigraphic sequences and aquifer/reservoir potential: with analog shelf to shoreface examples from the Atlantic Coastal Plain Province, U.S.A. by Kathleen M. Farrell, W. Burleigh Harris, David J. Mallinson, Stephen J. Culver, Stanley R. Riggs, John F. Wehmiller, Jessica Pierson Moore, Jean M. Self-Trail, and Jeff C. Lautier