The potential of CEOR application in mature oil fields can be investigated using sector models of an appropriate boundary conditions. In this paper, we present an evaluation of feasibility study of surfactant and estimation of the incremental recoverable oil in a mature Libyan oil field assuming the availability of surfactant formulation with optimal performance at reservoir conditions. Overall permeability of reservoir rock is rather low which limits the applicable areas of CEOR applications.
Reservoir properties were characterized using an established optimization approach to define pilot areas that exhibit favorable conditions for chemical EOR flooding. An intensive study was accomplished to generate a sector model of an optimum boundary conditions that provide pronounced results to the Full Field Model (FFM). Typical laboratory data were used to design surfactant model at an ultra-low interfacial tension (IFT) of 10−3 mN/m. Furthermore, main parameters that could influence the results of surfactant model were optimized: flow rates, residual oil saturation (Sorc), correlated Capillary De-Saturation Curve (CDC), adsorption, and grid size effect.
Interstitial velocity of displacing fluid and capillary number were correlated to describe the effect of permeability variation on the ultimate residual oil saturation. Additional recovery by surfactant at current reservoir conditions appeared to be strongly affected by changing the correlated CDC. The estimated macroscopic efficiency of surfactant by the coarse and fine grid models indicates that the surfactant is being smeared in the coarse model, and consequently different pressure distribution in both models was observed after certain time of injection. Moreover, the predicted results illustrate the influence of any heterogeneity feature in reservoir properties on both microscopic (ED) and macroscopic (EV) sweep efficiencies of CEOR flooding.
In Addition to the lessons learned of proper simulation at field scale, a developed approach to evaluate the potential of CEOR at challenging reservoir conditions is introduced in this paper.