Uncertainty Study of Time-lapse Seismic Data in a Carbonate Field

To fully evaluate the results and achievement of a time-lapse seismic, we need to determine the uncertainties of the seismic signature changes. In this paper, we study the uncertainty of a time-lapse seismic in a carbonate reservoir in the Middle East. We combine statistics and analytical methods to study the uncertainties in compressional velocity, acoustic impedance and seismic amplitude. We find, in general, that the uncertainty increases with thickness. The uncertainty at the facies is considered intermediate as it honors the geology but it carries variations in fluid content along. In addition, Gassmann predictions seem to under-estimate fluid changes. We propose an approximated equation to evaluate uncertainties in seismic amplitude. Finally, we calculate that the signal-to-noise ratio should be higher than 6 (15.56 dB), for detecting physical time-lapse seismic changes in this data.