Handling Subsidence Uncertainty in Stochastic 1D Reservoir Theoretical Aspects and Applications to a North Sea Reservoir Case Study.

@inproceedings{Royer3GM2009,
 abstract = { Geomechanics modeling is nowadays an unavoidable step in reservoir studies, especially for stress sensitive rocks analysis, or when reservoirs are subjects to strong poro pressure variations due to hydrocarbon production or gas/water injection. In this study, a 1D theoretical framework is developed accounting for uncertainties on the lithofacies and rock mechanical properties. It is used to assess mechanical risks like subsidence and failure. Theoretical formulas to estimate the total vertical displacement and the effective horizontal stress variances together with the failure probability are derived for both fixed and stochastically simulated lithologies assuming a constant Biot coefficient. They depend on lithofacies proportions, lithology shearing and bulk modulus uncertainties, and on the variogram slope at the origin of the spatial litholofacies model. The theoretical and simulated results are in agreements on a reference 1D typical stratigraphic column from a hydrocarbon reservoir located in the North Sea. They show in all cases that both the subsidence and effective horizontal stress are equal in average to those estimated in the deterministic case. The subsidence and effective horizontal stress variation coefficients are three to four time greater when the lithology is unknown and stochastically simulated. The lithofacies with a higher variability, but also with a larger spatial range and a greater proportion contribute the most to the subsidence uncertainty, to the effective horizontal stress variability, and to the failure probability risks. This theoretical framework is a powerful tool to provide a first estimate of subsidence and failure probability risks in sensibility analysis, before conducting more advanced analyses using sophisticated numerical 2 or 3D studies. },
 author = { Royer, Jean-Jacques AND Hu, Tianmeng },
 booktitle = { Proc. 29th Gocad Meeting, Nancy },
 title = { Handling Subsidence Uncertainty in Stochastic 1D Reservoir Theoretical Aspects and Applications to a North Sea Reservoir Case Study. },
 year = { 2009 }
}