Modeling, Simulation and Interpretation of Spontaneous Potential Logs

The Spontaneous Potential (SP) log has served for decades as a borehole correlation log and, under favorable circumstances, for the reliable in-situ assessment of water resistivity in rock formations of interest. Nevertheless, it is known from laboratory and field measurements that SP logs are sensitive to the presence of hydrocarbons. This work introduces the principles of SP log modeling using a mechanistic approach and describes their implementation in a SP log numerical simulator. Various synthetic and field cases verify the capabilities and improvement due to numerical modeling in the interpretation of SP logs.