Evaluation and Optimization of Conformance Control by Modified Starch Gel in Low Permeability Cores with Fracture

Abstract

The artificial or natural fracture network in low permeability reservoirs provide drainage passages for the oil, but cause severe channeling during the water flooding. The best solution is to inject water shutoff agent to plug the water channels and enhance sweeping volume by bypassed water. This study introduces a new formula of conformance control agent -modified starch gel system, and experiments are conducted to evaluate its physical properties, optimal injection volume as conformance modifier, and its performance in fractured cores of low permeability. Experiments shows that the gel has high elasticity, strength and toughness in gel form, and can be injected into the fractured core under low differential pressure in solution form. The gel slug is strong enough to seal the fracture and resist washout after gel placement. Core flooding experiments indicate that the pressure gradient of gel displacement in the fracture is enough to divert the subsequent water to sweep the matrix, enhancing sweeping volume of water.