A Next-Generation Wireline NMR Logging Tool

摘要

This paper discusses design and implementation of a newgenerationnuclear magnetic resonance (NMR) wirelinelogging tool. The tool is a multifrequency, eccenteredgradient-field design with multiple depths of investigation(DOI) spanning a range of several inches. The broad range ofDOIs enables radial profiling of saturation distribution andformation damage. Because of the eccentered mode ofoperation and sensor design, the DOIs are maintainedregardless of hole size and temperature. The DOIs range from1 to 4 in.The tool features multiple sensors, including a largeantenna for fluid characterization and complementary smallapertureantennae for high-resolution acquisition modes. Thesensors can be operated either separately or simultaneously atlogging speeds of up to 3,000 ft/hr. Comparison of theresponses is used to provide high-resolution identification oflong T1 fluids such as light hydrocarbons.New NMR acquisition sequences such as DiffusionEditing (DE?) are readily implemented on the new tool, whichhas a highly flexible pulse programmer. Combining the newacquisition methods with the multifrequency capability of thetool and Magnetic Resonance Fluid (MRF*) characterizationprocessing provides robust fluid saturation and oil viscosityanswers.