A New Cross-Correlation Method for Analysing Well Log Data

In this work we performed a series of cross correlation and complexity analysis of raw well log data using cross wavelet analysis. The possible connections between natural gamma ray radioactivity (CGR) of earth and other log data such as Neutron porosity (NPHI), Sonic Transient Time (DT), Bulk Density (RHOB) and Electrical Resistivity (ILD) of oil and gas reservoirs are shown in this study using cross wavelet transform (XWT) and wavelet coherency. The casual relationships between gamma ray (CGR) log data and porosity logs in the depth-frequency space were demonstrated. Cross wavelet analysis reveals that the links between CGR and NPHI is stronger than that between CGR and DT or CGR and RHOB. The CGR has a minor effect on ILD at any scale.