... been shown to control the swelling of shales both qualitatively and quantitatively. A correlation derived from basic physical principles for the cation exchange capacity (CEC) of shale formations using common log data of temperature, resistivity, and sonic slowness has been modified using available...

... in the resistivity log and the sonic log. These lines are compared quantitatively to the original log curves to identify and filter out data points associated with factors that perturb the trend between sonic slowness and resistivity. Techniques used to derive the resistivity baseline (curve smoothing techniques...