Patent ID: 6597170
Filing Date: 2003-07-22
Classification: G01N,G01V

Abstract:
A method of making nuclear magnetic resonance measurements of an earth formation using a multifrequency gradient logging tool conveyed therein, the method comprising:(a) magnetically polarizing nuclei in said earth formation with a static magnetic field having a gradient therein; (b) acquiring a first echo train in a first sensitive volume of the earth formation for determining a parameter thereof, said first echo train produced by a first pulse sequence comprising a first RF frequency, a first shaped tipping pulse and a first plurality of refocusing pulses at said first RF frequency; and (c) acquiring a second echo train corresponding to a second sensitive volume of the earth formation different from the first sensitive volume for determining a parameter thereof, said second echo train produced by a second pulse sequence comprising a second RF frequency, a second RF tipping pulse and a second plurality of refocusing pulses at said second RF frequency; wherein a shape of said first tipping pulse is selected to reduce an interference (overlap in the frequency domain) between said first tipping pulse and a refocusing pulse of said second pulse sequence and a resulting disturbance of magnetization in said second sensitive volume by said fist pulse sequence.