Time lapse (4D) seismic for reservoir fluid saturation and monitoring: Application in Malaysian Basin

Time lapse (4D) seismic is a valuable technology that provides vital information for field development plans and reservoir management. 4D seismic is extensively being used by oil and gas companies as a reservoir surveillance tool for better estimation of reservoir dynamic properties and reducing uncer-tainties of simulation models. As a result of production and enhance oil recovery activities (EOR) reservoir dynamic properties such as fluid saturation, pressure and temperature are being subjected to change which can occur independently or a combination of changes may happen in a reservoir. In this article 4D seismic technology is used to qualitatively monitor fluid saturation distribution and remaining oil using repeated 3D seismic surveys of base and monitor which are acquired in 1995 and 2006 respectively. This study integrates seismic data (base and monitor) and well log data from a mature field in the Malay basin with six years of water injection history. To predict water saturation post-stack seismic inversion is performed to extract acoustic impedance of base and monitor surveys and used them as an input for artificial neural network (ANN). 4D seismic data analysis enabled us to qualitatively interpret and identify areas of bypassed oil, generate maps of water movement pattern and guide the infill drilling activities. This methodology has the potential to further extend the life of the field and improving the recovery factor.