Patent ID: 7755032

Claim:
A method for evaluating an inflow performance for completed intervals in a well, comprising: pulsing neutrons into a fluid flow in the well; detecting gamma rays from decays of nitrogen-16 in the fluid flow with a first gamma ray sensor to generate a measurement of gamma ray decays; determining an in situ water velocity from the measurement of the gamma ray decays by: measuring a first time for activated oxygen to flow from a pulsed neutron generator to the first gamma ray sensor; and dividing a first distance between the pulsed neutron generator and the first gamma ray sensor by the first time for the activated oxygen to flow from pulsed neutron generator to the first gamma ray sensor; estimating the inflow performance for each of the completed intervals in the well based on a change in the in situ water velocity, wherein inflow performance of a first one of the completed intervals is determined by subtracting at least data collected relating to a second one of the completed intervals from the fluid flow; and correcting the in situ water velocity to generate a corrected in situ water velocity for a hydraulic flow area in the fluid flow, determined using an inside diameter of a flow conduit and a cross sectional area of a pulsed neutron logging tool comprising the pulsed neutron generator and the first gamma ray sensor, using following equations: v wc ⁢ = v wl ⁢ A p ⁢ ⁢ t A P A p ⁢ ⁢ t = 0.005454 ⁢ ⁢ d e 2 . wherein ν wc represents the corrected in situ water velocity, ν wl represents log-reported water velocity, A pt represents hydraulic area around the pulsed neutron logging tool, and A p represents cross sectional area of the fluid flow, and wherein d e is equal to (D−d), d represents outside diameter of the pulsed neutron logging tool, and D represents inside diameter of the flow conduit, and wherein area is in units of square feet and diameter is in units of inches.