Confirming Rw By Reconstructing The S.P. Using Formation Evaluation Results Employing Gradient Field Magnetic Resonance Logs

The new NMR measurements; mineralogy free porosity, direct hydrocarbon volume and type and its tie to CEO, have brought a new level of quality to log derived water saturation both in the flushed and virgin conditions. However, the inversion of resistivity logs into water filled porosity remains heavily dependent upon the resistivity (Rw) of the formation water, and having no direct measure of Rw the analyst, on many occasions is left unsure of the Rw value to use. Such an event led to a search for methods which could be employed to quality control the Rw selection, a method that was found through use of NMR and the SP.