Abstract
The East Bodo, Lloydminster SS heavy oil pool has been exploited using primary
recovery and waterflood. IOR screening showed that a polymer flood would be a
preferred IOR technique. Subsequent coreflood tests indicated that the polymer
flood could recover 20% OOIP incremental oil, after waterflooding, to a 95%
water cut. Data gathered from the coreflood was used to fine tune the reservoir
simulation model to help design the pilot and predict potential economic
reserve capture for a commercial field-wide polymer flood. Subsequently, a
pilot was initiated. During the pilot operation, achieving the target polymer
viscosity, dependant on water quality, proved to be a significant challenge.
Early field response is being observed through an increase in injection
pressure, reduced water cut and polymer breakthrough. Further positive response
of this polymer pilot allows for the expansion of the polymer flood technology
to other parts of this reservoir; some with bottomwater and gas cap. This paper
reviews the progress of the East Bodo polymer flood, from laboratory concept to
working field application, in four major steps: 1) IOR screening using
simulations and coreflooding, 2) field pilot design/implementation, 3) pilot
performance, and 4) next steps.
Introduction
Pengrowth has targeted East Bodo (Alberta side) and Cosine (Saskatchewan side)
for waterflood optimization and subsequent enhanced oil recovery applications.
Currently, the most practical EOR technology for this heavy oil reservoir seems
to be the polymer flood technology in combination with horizontal wells.
Several investigators(1-4) have demonstrated the potential of the
polymer flood technology for improved oil recovery in heavy oil
reservoirs.
The East Bodo/Cosine Reservoir produces from the Lloydminster Formation, which
is part of the Lower Cretaceous Mannville Group. Pengrowth provided some of the
reservoir characteristics, as summarized in Table 1. This particular reservoir
is separated into two parallel lobes trending North/West to South/East.
To complicate matters, local gas caps are found primarily on the Saskatchewan
side of the reservoir. Thus, the current waterflood patterns are located on the
Alberta side. In the future, optimized waterflood and EOR schemes need to
include those parts of the reservoir which are overlain by gas caps or
influenced by bottomwater. A plan of progression aligned with the priorities of
Pengrowth was laid out as follows:
- Optimize existing waterflood;
-
- Step out waterflood into limited gas cap areas;
-
- Then, target areas with a more extensive gas cap;
-
- Determine enhanced waterflood potential, for instance polymer flood;
and
-
- Arrange well patterns to benefit both waterflood and subsequent EOR
process.
IOR Screening
Several IOR technologies were considered for application in the East Bodo
Field. What follows is a list of IOR processes that were initially considered,
but screened out after technical or economical issues could not be
overcome.
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- Thermal Recovery: Pay is too thin - heat loss to overburden is too large;
oil not viscous enough to form a stable steam chamber; fireflood has potential,
but a previous pilot on a neighbouring McLaren pool yielded poor results.
-
© 2009. Petroleum Society of Canada (now Society of Petroleum Engineers)
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History
- Original manuscript received:
29 March 2007
- Meeting paper published:
12 June 2007
- Revised manuscript received:
9 December 2008
- Manuscript approved:
5 January 2009
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