Patent ID: 6844728
Filing Date: 2005-01-18
Classification: G01N,G01V

Abstract:
1. A method for use with an NMR measurement apparatus located in a borehole surrounding an earth formation and subject to relative motion between the apparatus and a sample located in an investigation region of the earth formation, the method comprising: selecting a set of initial RF pulse characteristics defining one or more RF pulses; radiating a first sequence of RF pulses to substantially saturate a first region of the sample, the first sequence comprising two or more RF pulses and having an envelope, the envelope defined by RF pulse characteristics associated with individual RF pulses, the RF pulse characteristics selected from the group including, amplitude, phase, duration and time interval between RF pulses; varying at least one of the group of RF pulse characteristics of the envelope for one or more subsequent RF pulses within the first sequence during the radiation of the first sequence to substantially saturate the first region of the sample; radiating a second sequence of RF pulses to establish a resonance region within the first region; detecting an NMR response to the second sequence from the resonance region within the first region; and measuring an attribute of the sample of the earth formation based on the NMR response.