Patent ID: 8884216
Filing Date: 2014-11-11
Classification: G01V

Abstract:
1. A method for obtaining a pulsed neutron-induced gamma-ray response that is substantially free of sensitivity to the hydrogen index of a formation and related to formation inelastic cross section weighted atom density/electron density for formation evaluation, the method comprising: generating a neutron burst with a pulsed source of high energy neutrons; detecting a plurality of gamma-ray counts by at least one gamma-ray detector, at least one number of burst counts being detected during a first time interval, during which the pulsed source is activated and at least one number of non-burst counts being detected during a second time interval during which the pulsed source is not activated; outputting a quantity GRat relating to a formation parameter of interest, wherein GRat is substantially free of sensitivity to a hydrogen index of the formation and is calculated as a function of the number of non-burst counts detected during the second interval and the number of burst counts detected during the first interval; enhancing a high porosity response of a hydrogen index measurement using GRat when a porosity of the formation exceeds 30 p.u.