A method is provided to estimate the pore volume of a formation occupied byhydrocarbon phase or phases, the method comprisingthe steps of: obtaining a first pulsed NMR log of the formation, the pulsesequence of the first NMR log comprising an initial 90° radiofrequency pulse, followed by a series of 180° radio frequency pulsesstarting at a time period t cp1 after the initial 90° pulse, and theseriesof pulses comprising magnetic pulses each separated by a time period 2t cp1;obtaining a second pulsed NMR log of the formation, the pulsesequence of the second NMR log comprising an initial 90° radiofrequency pulse, followed by a series of 180° pulses starting at a timeperiod t cp2 after the initial 90° pulse, and the series of 180°pulses comprising radio frequency pulses each separated by a time period 2tcp2wherein the time t cp2 is a time that is different from t cp1 by an amount oftime sufficient to separate resultant peaks of transverse relaxationtimes attributable to the hydrocarbon phase or phases within the formation;and determining, from the first and the second NMR logs,the pore volume of a formation occupied by hydrocarbon phase or phases withinthe formation. In a preferred embodiment, pore volumeoccupied by hydrocarbon gas is determined, and t cp2 is a time that is greaterthan that which results in the measured transverse relaxationtime of the hydrocarbon gas being less than about 210-3 seconds and t cp1 is atime that is less than that which results in the measuredtransverse relaxation time of the hydrocarbon gas being greater than about 4 x10-3 seconds.
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