Velocity‐porosity‐clay content systematics of poorly consolidated sandstones

Abstract

Compressional velocities have been measured as a function of confining pressure for 14 West Delta Block (Louisiana) sandstone cores. The dry velocity data for these poorly consolidated sandstones at 10 MPa confining pressure plot on a linear velocity‐density trend with well‐consolidated sandstones but not loose sands. The dry velocity data also show linear trends of decreasing velocity with increasing porosity along contours of constant clay content similar to those obtained at 40 MPa by Tosaya and Nur (1982) for saturated sandstones. The spacing between clay contours indicates that a large portion of the velocity variation with clay content is due to microporosity, which is not included in point counting, within the clays. The slope of the velocity‐porosity trends indicates that cementation increases with decreasing porosity.