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.