Patent ID: 8903658

Claim:
A method of estimating fluid composition in an earth formation, comprising: generating at least one pulsed neutron measurement by a pulsed neutron tool; estimating a pulsed neutron fluid saturation by analyzing the at least one pulsed neutron measurement via a pulsed neutron model of the earth formation, the pulsed neutron model including expected pulsed neutron measurements relative to selected fluid properties, the selected fluid properties including a composition of gas in the fluid, wherein estimating includes selecting a proportion of a non-hydrocarbon gas in the fluid for the pulsed neutron model; comparing the estimated pulsed neutron fluid saturation to a reference fluid saturation estimated via a downhole tool; adjusting the pulsed neutron model to at least substantially eliminate a difference between the pulsed neutron fluid saturation and the reference fluid saturation by adjusting at least the proportion of the non-hydrocarbon gas in the fluid; and estimating fluid properties based on the adjusted model.