Prediction of porosity and water saturation of chalks from combined refraction seismic and reflection ground-penetrating radar measurements

Abstract

The prediction of porosity and water content of near-surface chalks is important for agricultural, environmental, hydrologic, and geologic engineering investigations. However, current methods based on laboratory measurements or crosshole ground-penetrating radar (GPR) are typically costly and applicable to only a limited area. We have combined the refraction seismic and reflection GPR data sets measured on the ground surface along a 96 m long profile line to predict the porosity and water saturation simultaneously. Using integrated rock-physics templates, we develop and apply a quantitative method that combines acoustic and electromagnetic velocities to estimate the petrophysical parameters of chalks. The seismic and GPR data are processed independently and subsequently combined to invert the porosity and water saturation. Field data tests demonstrate that the predicted results are consistent with laboratory measurements and field observations, demonstrating that the integration of seismic and GPR data facilitates efficient and reliable estimates of the porosity and saturation of chalks on scales relevant to regional field mapping. Hence, this method allows the petrophysical parameters of near-surface chalks to be evaluated efficiently at a regional scale.