Reservoir Monitoring in Low-Salinity Environments With Pulsed-Neutron-Capture and Gamma Ray Logs

Accurate quantitative interpretation of pulsed-neutron-capture (PNC) logs cannot be achieved in the low-salinity formation-water environment of the Gippsland basin because formation fluid responses are small relative to uncertainties introduced by lithologic variation. Time-lapse interpretation is used effectively although formation responses often are masked by larger responses caused by changes in the logging environment. Several easy techniques, such as using the gamma ray log to indicate formation-water movement, are used to aid interpretation.