Applications of a New-Generation NMR Wireline Logging Tool

This paper discusses applications of a new-generation, nuclear magnetic resonance (NMR) wireline logging tool. The new design is a multi-frequency, eccentered, gradient-field NMR logging tool with multiple depths of investigation, which are maintained regardless of the hole size and are deeper than those of previous NMR logging tools. The new-generation tool features a high-resolution acquisition mode, making it possible to perform both fluid characterization and thin-bed analysis. We present the results of MRF* Magnetic Resonance Fluid characterization logging in a range of different environments. MRF acquisition modes comprise suites of spin-echo sequences having sensitivity to molecular diffusion. Simultaneous analysis of an entire suite of data provides depth logs of oil viscosity and fluid saturations measured in the near-wellbore region as well as total porosity, T₂ distributions, and permeability estimates. Several logs acquired in different formations are used to demonstrate the high-resolution capability of the new tool. Data acquired in a test well with known characteristics are used to validate the vertical resolution, precision, and accuracy of the measurements.