A new nuclear magnetic resonance (NMR) wireline logging tool eliminates the need for multiple passes through zones of interest as required by conventional NMR systems. Called the MRX, for Magnetic Resonance eXpert, the tool is particularly suitable for complex applications such as carbonate formations and low resistivity pay zones. In deepwater environments, the ability to quantify fluid viscosity accurately and profile fluid volumes and saturations radially in real-time enables users to make informed decisions while minimizing rig time.
Key to the tool's design are multiple antennae that enable multiple depths-of-investigation over a broad range that is independent of hole diameter, high magnetic field gradient and advanced, diffusion-based, NMR fluid characterization. These features enable identification and quantification of multiple fluids in the near wellbore region using molecular diffusion mapping. They also allow real-time oil viscosity measurement in a continuous log with very high vertical resolution. In addition, the tool performs radial profiling of fluid volumes and saturations for light hydrocarbon detection and formation damage analysis, as well as rock quality and producibility estimation.
Recently, a Louisiana well was drilled through an oil-bearing sand. Referring to the log one can see that MRX tool answers included oil viscosity (A) and indicated no moveable water in the oil zone. Filtrate invasion from the water-based mud (B) is indicated at 1.5-in. depth of investigation. And at 2.7-in. depth of investigation, reduced drilling mud invasion is observed (C).