MULTIPLE COILS FOR NMR WELL-LOGGING MEASUREMENTS

摘要

An NMR apparatus disposed in a wellbore and having an array of two or more NMR sensors located at substantially the same axial position on the NMR apparatus and having different directional sensitivities is used to acquire an NMR signal from at least two of the two or more NMR sensors. The NMR signals are combined to obtain borehole information. The borehole information may include an azimuthal image of the formation surrounding the borehole. The azimuthal image may be a formation porosity image, a formation bound fluid image, a T2 distribution image, a T2 log mean image, a formation permeability image, or a formation fluid viscosity image. If two or more pre-amplifiers and receiver circuitry are also provided, the NMR signals may be combined prior to passing through the pre-amplifiers and receiver circuitry to improve the signal to noise ratio of the total signal from the desired sample space.