Image Processing of Acoustic Microscopy Data to Estimate Textural Scales and Anistropy in Shales

Abstract

We estimate different statistical measures for quantifying heterogeneity and textures from scanning acoustic microscope images of shale microstructures. The analyzed shales covered a range of depths, kerogen content, and maturity. We observed quantifiable and consistent patterns linking texture, shale maturity, and elastic P-wave impedance. The textural heterogeneity and P-wave impedance and velocity, and density increase with increasing maturity (decreasing kerogen content), while there is a general decrease in textural anisotropy with maturity. We also found a reasonably good match between elastic impedance estimated from SAM images and impedance computed from ultrasonic measurements. The textural anisotropy ranges from 10% to about 70% and tends to decrease with increasing depth and maturity