Abstract

Characterizing fracture content of subsurface siliceous rocks susceptible to fracturing is a complex process. We have experimented with the use of the Hurst coefficient and have noted the autocorrelated nature of particular subterranean intervals that contain biogenic silica in various stages of diagenesis. We examined the nature of lithology signals from well logs and have ascertained the existence of long-range dependence and persistency. We based our analysis on gamma-ray and neutron logs vs. depth and examined the autocorrelation of the sequential appearance of highly cherty intervals. The Hurst coefficient is used as a measure of the autocorrelation of the log readings vs. depth as verified by Power Spectrum Density plots. Our analysis detects a persistency in the lithology data in the intervals significantly affected by the silica diagenesis.