Rock physics and statistical well log analyses in marly chalk

摘要

Analyses of the variations in porosity, clay content, and compressional velocity and modulus in marly chalk allow better interpretation of seismic data in terms of subsurface petrophysical parameters. We present a study of variations in logging data from a marly chalk field. Our study includes log data of velocity, density, neutron-porosity, natural gamma-ray, and resistivity measurements. In order to honor the various factors that interact to produce a suite of well log responses, we investigate the interdepen-dencies using a multivariate principal component analysis (PCA). The main advantage of PCA is that no a priori information is required about the location, lithology, saturations, etc. to get an initial idea about the field. This means that PCA, even with only limited information, can help recognize trends in the data and separate lithology and saturation.