Integrated approach to condensed section identification in intraslope basins, Pliocene-Pleistocene, northern Gulf of Mexico (E & P Notes)

Abstract

In this article we present a series of techniques for identifying condensed sections on wire-line logs for sediments deposited in intraslope basins. A sequence stratigraphic framework can be developed quickly by integrating high-resolution biostratigraphic data from wells having wire-line logs, mud logs, and seismic data. We developed these techniques from working with Pliocene–Pleistocene sediments of the northern Gulf of Mexico. We recognize two major types of condensed sections: carbonate-rich condensed sections (CRCS) and shale-rich condensed sections (SRCS). Paleontologically, both CRCS and SRCS are characterized by high calcareous nannofossil and foraminiferal relative abundance and an increase in diversity. The CRCS have a low gamma-ray (siliciclastic sand) signature and high spontaneous potential (SP) (at or near shale baseline) wire-line log response. The SRCS are characterized by gamma-ray and SP responses that are approximately at the shale baseline or slightly higher on wire-line logs. These two types of condensed sections can occur within the same depositional sequence, suggesting multiple factors controlling the kinds of sediments deposited within a condensed section.