StatoilHydro is the first company to implement a superior seismic inversion technique for static reservoir characterization and quantitative time-lapse seismic analysis
Inversion is an advanced technique for extracting quantitative information about reservoir rocks and fluid parameters from seismic data.
Many methods are available, but a new one developed by StatoilHydro and the Norwegian University of Science and Technology (NTNU) has a number of advantages over its competitors.
The use of seismic "amplitude-versus-angle" data formulated in a (Bayesian) statistical setting lies at the heart of the technique.
"Angle" refers to the way in which the angles between downward and upward travelling seismic waves change according to the increasing distance (offset) between a seismic source and consecutive hydrophones.
The method basically calculates various seismic parameters from which porosity and other static reservoir properties can be derived. The results can also be fed into computerized, 3D reservoir models.
The major advantage of the method is that uncertainties can be quantified.
The solution is also spatially coupled, which means that it can be coupled to well log observations of the same rock properties and used in stochastic reservoir modelling. A priori knowledge of reservoir geology can also be incorporated.
The method has been successfully tested on seismic data from the StatoilHydro-operated Smørbukk field to improve porosity prediction, and adapted for ‘dynamic’ reservoir monitoring using time-lapse (4D) seismic.
The products from 4D seismic inversion are data cubes of pressure and fluid saturation changes, which have occurred some time after a field has been in production.
