4D seismic for carbonate reservoir management and monitoring -Proof of concept from the giant al Shaheen Field, offshore

A proof of concept approach has been taken for the Al Shaheen Field before implementing a 4D surveillance program into the field management and surveillance. The proof of concept is not only to fully demonstrate that a 4D signal is present, but also to be able to quantitatively understand it and to derive information about the recovery processes from it. Two overlapping surveys, one acquired in 1993 (before production) and the other in 2006 showed that 4D signals could be observed in the Al Shaheen Field. In order to assess such potential a cross-discipline workflow was applied that integrates the forward modelling of seismic synthetic time changes for the two main reservoir intervals combining the in-house rock physics model with reservoir simulation models and the use of the in-house time-strain inversion algorithm. Comparison of synthetic and measured time thickness attributes showed good correspondence with regard to intensity, size, and shape of the production affected areas suggesting that the forward model successfully reproduces the actual cause of the changes. 4D seismic signals in the two main reservoirs can be related to fluid and pressure effects and consequently flood front position can be derived from seismic data.