Reducing Oil Bypassed during CO2 Flooding in Fracture-Dominated Reservoirs

Abstract

Injection rates play a very important role in affecting the recovery process, especially in the presence of fractures. At high injection rates faster CO2 breakthrough of CO2 and higher oil bypass were observed than at low injection rates. But very low injection rates are not attractive from an economic point of view. Hence water viscosified with a polymer was injected directly into the fracture, to divert CO2 flow into the matrix and delay breakthrough, similar to the WAG process. Although the breakthrough time reduced considerably, water �leak off� into the matrix was very high. To alleviate this problem, a cross-linked gel was used in the fracture for conformance control. The gel was found to overcome �leak off� problems and effectively divert CO2 flow into the matrix. This experimental research will serve to increase the understanding of fluid flow and conformance control methods in fractured reservoirs.