Optimization Of Slugs Combination Flooding In Heterogeneous Reservoir

Nowadays,slug combination(polymer,surfactant,gel or their combination)has drawn more attention than single slug due to its synergistic effect on oil recovery.Polymer flooding has been applied for decades,but due to high demand of hydrocarbon,coupled to the difficulties faced in heterogeneous formations,effective methods have to be developed.Therefore,the overall objective of this study was to optimize a better slug combination method for good recovery factor in heterogeneous reservoir.To achieve the objectives of the study,laboratory experimental tests and numerical simulation were conducted.The laboratory experiments aimed in selecting an optimal scheme for the slug combination flooding through EOR chemicals.Various parallel sandpacks without crossflow were conducted.A one-dimensional model in CMG-STARS simulator was built to match the laboratory experiments results and simulation data.The model was up-scaled to three-dimensional conceptual model and sensitivity analysis was studied.This study illustrates the use of gel as front slug greatly resulted in increase of oil recovery due to its plugging effect in high permeability regions and reduce the water-oil mobility ratio.Subsequently injecting the latter slug into sandpack,permits more chemicals move to low permeability zones,which increased the flow out of remaining oil effectively,and displacement efficiency.The results showed that experimental optimized formulation of 0.3 PV Gel + 0.3 PV SP gave oil recovery of 63.93% and 75.89% in high and low permeability layers while simulation results gave an excellent history matching with 64% and 75.9% in high and low permeability layers respectively.However,the sequence 0.2 PV Gel + 0.3 PV SP gave highest oil recovery for the slug combination flooding in the CMG-STARS with a reasonable injection rate of 0.08 PV/a.