Single-Well Simulation Study of Foam EOR in Gas-Cap Oil of the Naturally-Fractured Cantarell Field

Abstract

Abstract This paper presents results of a simulation study to investigate foam-assisted chemical EOR surfactants that target recovery of oil from the vast volumes of bypassed oil in the tight and oil-wet matrix in the gas cap of the naturally fractured Akal field of Cantarell complex. First, gravity drainage in a 1D column of stacked matrix blocks of Akal gas cap is simulated with both fine-scale single-porosity and coarse-scale dual-continuum media under the conditions of capillary continuity and discontinuity. This establishes that a combined dual-porosity and dual-permeability coarse scheme is appropriate as the representative modeling method. Next, 2D cylindrical and 3D Cartesian single-well models with fluid and rock properties of Akal field are constructed and aqueous solutions of foaming and EOR-surfactants are co-injected in the nitrogen gas stream through vertical or limited-entry side-tracked horizontal wells. Simulation approaches are developed that formulate the impact of foam on fluid flow within fractures, wettability alteration and subsequent imbibition of EOR surfactant solutions into matrix for accelerated gravity induced EOR of matrix oil. Sensitivity studies with respect to foam quality, foam strength, processes of wettability alteration and ultra-low tension EOR and well geometry configurations are conducted. Use of horizontal injector and producer help better confine the released oil within the testing interval and aid in assessing the efficiency of foam-EOR method for gas cap matrix oil.