OIL REINJECTION TO MITIGATE SOLVENT CONING

After solvent breakthrough, vertical miscible floods are characterized by rapid increases in producing gas-oil ratios, which in turn are acc ompanied by rapid declines in oil production. At this advanced stage o f depletion, the vertical floods have a low reserve life index and, he nce, major investments cannot be justified fled to extend the producin g life of these floods. Imperial Oil Resources Limited, in its search for new low cost techniques to increase reserves while maintaining/inc reasing oil production, began to examine the concept of oil re-injecti on in its Pembina Nisku reservoirs. Exploratory laboratory tests and n umerical simulation work demonstrated that a dual completion to re-inj ect part of the produced oil back into the formation, a few metres abo ve the producing perforations, could lead to incremental recoveries. S imulation results specifically showed a 2 - 3% of the original-oil-in- place (OOIP) increase for the model studied. A field test to evaluate the benefits of the oil re-injection process is presently being conduc ted in the Pembina Nisku ''Q'' pool. Initial results indicate that oil re-injection is successful in controlling solvent production while ma intaining oil rates. As a consequence, additional piloting to expand t he applicability of the oil re-injection process is being planned for other Nisku and Imperial Oil reservoirs.