Intensive Use of 4D Seismic in Reservoir Monitoring, Modeling and Management: the Dalia Case Study

Born nearly thirty years ago, time lapse (4D) seismic monitoring technology has been developed in some cases to monitor fluid movement and to distinguish between drained and un-drained portions of a reservoir. It allows quantitatively improving reservoir models, particularly their predictive capability. Indeed, the benefits of time-lapse seismic for reservoir characterization depend on the quality of 4D acquisition and processing, but they also greatly depend on the particular 4D inversion and interpretation methods used. Finally, a decisive aspect is certainly the capability of integrating results from different disciplines in an effective way. Timing is also crucial: results delivered in a few months can have a direct operational impact such as field monitoring or well location and design optimization. For the last ten years, Total has recognized the importance of time lapse seismic and has therefore conducted 4D seismic monitoring in different geological environments. Examples of 4D experiences range from monitoring of water injection and production for complex reservoir management and field development in the Gulf of Guinea (Angola and Nigeria); monitoring of geomechanical effects in HPHT fields (Elgin-Franklin, UK), in compacting reservoirs in Norway (Ekofisk and Valhall) and in the Gulf of Mexico (Matterhorn, US); monitoring of steam chamber in tar sands (Surmont, Canada) and monitoring of compaction and water rise in carbonates (South-East Asia). This paper focuses on the intense use of 4D seismic on the DALIA Field (Angola, Block 17).