Patent ID: 6720765
Filing Date: 2004-04-13
Classification: G01N,G01R,G01V,Y02A

Abstract:
A tool conveyed in a borehole for nuclear magnetic resonance (NMR) logging of an earth formation comprising:(a) a housing defining a longitudinal axis of the tool; (b) at least one sensor assembly coupled to the housing by an extension device, a body of said at least one sensor assembly adapted to make contact with a wall of a borehole in the earth formation, said sensor assembly including (A) a magnet for providing a static magnetic field in a sensitive region in said formation, (B) a transmitter coil for producing a pulsed radio frequency (RF) magnetic field in said sensitive region, and, (C) at least one receiver coil for receiving spin echo signals from nuclei in said sensitive region, said at least one receiver coil having an axis substantially parallel to an axis of said transmitter coil; wherein an axial extent of the transmitter coil is greater than an axial extent of the at least one receiver coil.