Introduction to Logging-While-Drilling Investigations of Faulting, Fluid Flow, and Seismic Images of the Northern Barbados Subduction Zone

Abstract

Deformation and fluid flow in sedimentary sequences alter physical properties. In situ measurements of physical properties evaluate diagenetic and structural processes (consolidation, cementation, and dilation) operating during deformation, fluid flow, and faulting. Because seismic images are affected by changes in physical properties, the measurement of physical properties allows the calibration of seismic data as a tool for remotely sensing evidence of deformation and fluid flow. Logging while drilling (LWD) can evaluate physical processes in situ, including transient borehole conditions. During Ocean Drilling Program Leg 171A, a series of LWD holes was drilled to measure physical properties through the Barbados accretionary prism. Extensive previous coring and a three-dimensional seismic survey provide a rich framework for log interpretation, seismic calibration, and evaluation of active diagenetic and structural processes. The results will assist interpretation of similar but less active systems in sedimentary basins elsewhere, contributing to the analysis of groundwater flow, hydrocarbon migration, and earthquake processes.