In a major oil producing field onshore Abu Dhabi time lapse monitoring logs were successfully used to map water saturation changes due to production and water injection activities. Two sets of data were used in the course of study; the first set is the behind casing sigma acquired using the PNC" Pulsed Neutron Capture" logs. The second set is the open hole Resistivity and porosity logs recently acquired while horizontalizing old wells. Time lapse water saturation logs provide an excellent presentation of dynamic flow processes in the reservoir and have been traditionally used in dynamic model calibrations during the history matching process. This study, however, presents an example of using dynamic information from these logs early in a reservoir characterization study. Geophysical interpretation described a very large number of faults with small throw with 2 major orientations in the reservoir studied. This poses significant challenges and one needs to understand and identify the important faults with dynamic impact prior to structural model building. For this purpose, water saturation movement maps are constructed and compared to some of the static data including structural deformations and fault patterns.
A striking relationship with the faulting pattern was observed, indicating possible conductivity of faults in N45W direction and sealing behavior of faults in N75W. As a result, the study has provided important information to better understand the dynamic impacts of faults and the results are now being used for improved data gathering and reservoir management activities
