Simulation of Enhanced Heavy Oil Recovery: History Match of Waterflooding and Polymer injection at Adverse Mobility Ratio
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Waterflooding and polymer flooding total recovery in the unstable immiscible displacement is very attractive and its applications are interesting in recent years. However, the simulation models of unstable immiscible flooding are not well understood and need more investigations and studies. The conventional method to simulate polymer flooding is to history match the waterflooding and uses relative permeability in addition to the bulk polymer rheology to predict the polymer flooding performance. In fact this straight forward method shows poor prediction abilities when the prediction results are compared to the experimental results The main objective of this thesis is to history match six experiments using Buckle-Leverette type displacement model. All experiments consist of unstable waterflooding and polymer flooding at adverse mobility ratio. Also, relative permeabilities for both waterflooding and polymer flooding are to be obtained. A sensitivity analysis was conducted to the models before starting history match. Numerical dispersion and physical dispersion were tested at the beginning to remove any numerical dispersion effect. After that, all polymer parameters that were used in the models were tested. Polymer viscosity, polymer concentration, polymer molecular weight, polymer adsorption, reversible and irreversible adsorption, inaccessible pore volume and the relative permeability were tested to investigate their degree of sensitivity in the history match. There were some program restrictions in which two experiments could not be simulated using STARS. The restrictions were regarding the differential pressure profile, which showed unreal responses to the sensitivity analysis. In the first part of this thesis, a history match was obtained for waterflooding using CMOST. Corey correlation for relative permeability was used to history match the cumulative oil production and the differential pressure. The history match was very good for all experiments in cumulative oil profile and not very well fitted in the differential pressure profile. In the second part of this thesis, a history match was obtained for polymer flooding. LET correlation for relative permeability was used to history match the cumulative oil production and the differential pressure. Also, other polymer parameters were used such as polymer adsorption, dispersion, inaccessible pore volume and resistance factor. A very good history match was obtained for all experiments. It was found that the relative permeability was the main factor that affect the history match in both waterflooding and polymer flooding. Although, the polymer parameters had significant effects, but there had some constraints and cannot be used freely, and therefore, only the relative permeability had the most significant role in obtaining the history match. Water end point relative permeability trend was determined for both waterflooding and polymer flooding.