Nuclear magnetic resonance and saturation well logs for determining free water level and reservoir type

摘要

Provided in some embodiments are systems and methods for determining characteristics of a hydrocarbon reservoir. Embodiments include conducting a nuclear magnetic resonance (NMR) logging operation of a targeted reservoir section of a wellbore extending into a hydrocarbon reservoir to generate a NMR log of the targeted reservoir section, conducting a resistivity logging of the targeted reservoir section to generate an uninvaded water saturation (S_w) log of the targeted reservoir section, determining for each of a plurality of depths in the section, a T₂ cutoff point based on values of the NMR and S_w logs, identifying a subset of the T₂ cutoff points that exhibit a hyperbolic trend, determining a theoretical cutoff curve corresponding to the subset of the T₂ cutoff points, determining a free water level (FWL) of the reservoir based on the theoretical cutoff curve, and determining a rock type of the reservoir based on the theoretical cutoff curve.