Linear Oil Displacement by the Emulsion Entrapment Process

Lack of mobility control is a major impediment to successful EOR, especially for high-viscosity oils. This paper presents experimental and theoretical results for continuous, linear, secondary oil displacement using dilute, stable suspensions of oil drops. The major hypothesis is that the oil/water (O/W) emulsion provides microscopic mobility control through entrapment or local permeability reduction not through viscosity-ratio improvement. To describe the displacement process, previous emulsion filtration theory is extended to longer cores and to two-phase flow. Agreement between theory and experiment is satisfactory for continuous secondary oil displacement with 1- to 2-μm [1- to 2-micron] diameter drops of volume concentrations up to 5 % in unconsolidated sandpacks with permeabilities ranging from 1 to 3 μm2 [1 to 3 darcies]. Dilute suspensions of stable oil drops in water also are successful in diverting flow in parallel-coreflooding to the lower-permeability core; therefore, they provide macroscopic mobility control.