Integration of NMR With Other Openhole Logs for Improved Formation Evaluation

摘要

The recently introduced measurement of total porosity form nuclear magnetic resonance (NMR) tools can help to identify the hydrocarbon type and to improve the determination of formation total porosity (φ_t) and water saturation (S_wt) in combination with other openhole logs. In shaly formations, porosities re difficult to estimate in the presence of hydrocarbons, especially those for gas and light oils. Water saturations are even more difficult to esti- mate because critical parameters such as clay cation exchange capacities/unit pore volume (Q_v), the formation factor (F) and formation water resistivity (R_w) might not be known. The latter quantities are essential inputs into the Waxman-Smits and dual- water model saturation equations.