Background Resistivity Prediction from Seismic Velocities

The interpretation of co-located CSEM and velocity data benefits significantly from integrated analysis and joint calibration due to the fact that, although each method responds to a distinct physical property, they both respond to the same rock and fluid volumes; useful correlations are therefore expected to exist. The literature describes empirical relationships between velocity and resistivity background depth trends. It has generally been noted that the primary petrophysical link between the two physical properties is porosity. Although this connection can be described using porosity-based rock physics models, we recognize that real log data often do not conform to strict theoretical assumptions; therefore, we adopt a data-driven approach to resistivity prediction that implicitly accounts for the underlying relationships without incorporating bias toward a particular rock physics model. Using this methodology, we predict background (non-hydrocarbon bearing) horizontal resistivity sections from interval seismic velocities for calibration of CSEM inversions. The background horizontal resistivity predictions generally have strong agreement with the CSEM inversion background resistivity.