Adaptive engineering-based scaling for enhanced dynamic interpretation of 4D seismic

In this study, importance is drawn to the role of engineering principles when interpreting and estimating dynamic information from 4D seismic data. It is found that in clastic reservoirs the principal parameters controlling mapped 4D signatures are not pressure and saturation changes per se, but the changes scaled by the corresponding thickness (or pore volume) of the reservoir volume that these effects occupy. Indeed, pressure and saturation changes cannot be recovered by themselves, and this is true for all data interpretation and inversion procedures. This understanding is validated both with numerical modelling and analytic calculation. Fluid flow studies also indicate that the impact of gas saturation on the seismic can be written using a linear term, and that inversion to gas saturation can only yield the thickness of the distribution. The above has provided a basis for a linear equation that can be used to easily invert for pressure and saturation changes. Quantitative updates of the simulation model can be achieved by comparing scaled dynamic changes from the simulator with the inverted observations