Mapping Reservoir Changes Using 4D Seismic Data at Simian Field, Offshore Nile Delta – Egypt

Abstract

Time-lapse seismic inversion method to reservoir management has proven to be a vital tool in the oil industry because of its effectiveness in tracking the pressure and saturation changes within the reservoir as well as identifying isolated bypassed accumulations. The 4D inversion process is critiqued to explore the pros and cons of 4D seismic inversions and how these could be improved. The major draw backs of the method are dependence on well log data quality, wavelet estimation and initial model construction whilst the potential gains are improved geological and geophysical classification of a seismic volume to a higher level than is possible with full-stack seismic data alone A 4D pre-stack simultaneous inversion was applied at the Simian gas field, part of the West Delta Deep Marine concession(WDDM), offshore Egypt with the aim of exploring the potential of this approach for time lapse quantitative interpretation. The Simian field is submarine channel based gas reservoirs that extend laterally over 25 km2. The nature of this channel has been well defined using full-stack seismic interpretation and from this producing wells have been drilled.