Multi objective assisted inversion of chemical EOR corefloods for improving the predictive capacity of numerical models
Abstract Reservoir modeling is a powerful tool to thoroughly assess chemical EOR performances and to design the economically optimal injection sequence (chemicals concentration, slugs size) However, while building a model requires a large amount of data, laboratory experiments allow assessing a non exhaustive number of parameters only. Some essential data besides remain costly or time consuming to acquire. The calibration process is thus not straightforward and typically results in under constrained models that may not provide meaningful results. To increase the model robustness, we propose to carry out a multiobjective assisted calibration, further tested on an additional differentiating experiment. The multi objective aspect refers to the calibration of various production data acquired from a consistent series of recovery experiments. The methodology is applied to five surfactantpolymer displacements performed on sandstone cores, differing from the surfactant slug concentration, its size and the brine salinity. The experiments set is chosen to provide a wide range of tertiary recoveries, from 52% to 86% of residual oil in place. The oil recovery and the differential pressure are history matched with a limited number of adjustable parameters among which the surfactant adsorption, the wateroil interfacial tension and the extrapolation of Corey exponents along flooding history. The sensitivity to adjustable parameters is thoroughly explored by more than 1000 simulations to finally get a model that successfully reproduces the main features of the experiments. Calibration on a few experiments then gives more confidence in the model than when done on a single experiment. Its ability to reproduce the processes occurring in the core and to further predict the optimal chemical injection sequence is reinforced by the additional differentiating experiment which segregates different consistent models. This additional experiment specifically better constrains the surfactant adsorption.