Successful pilot onshore Abu Dhabi shows that 4D can monitor fluid changes in a giant Middle East carbonate field

Abstract

Preliminary results from a time‐lapse 4D pilot study shows that saturation changes over time can be monitored in an onshore carbonate reservoir with the 4D surface seismic method. The 4D results were successful in showing that 4D responses can be observed in reservoir zones where sufficient saturation changes had occurred. The results of the 4D pilot showed that 3D seismic surveys can be repeated onshore with acceptable background noise levels, if done in the correct manner. Model predictions were found to be in agreement with the 4D results.4D responses were found in the main reservoir layer where saturation changes are occurring and not in the water leg where saturation changes have not occurred. The 4D responses are in good agreement with available well control by greater than 80 percent. Detailed 4D validation showed the 4D results to match available production logging tool (PLT) measurements surprisingly well. The results also suggest that pressure changes are contributing to some of the observed 4D responses. Based on the results of this pilot, it has been shown that 4D can monitor saturation changes in time in this carbonate reservoir. The 4D results are helping to assess sweep efficiency and identify potential bypassed oil reserves.