Existing pipelines and facilities, horizontal well lengths and interwell
spacing, and observation wells were also taken into account. A computing
cluster with 32 cores was used for the modeling process. Each simulation was
run 16-way parallel, effectively running two simulations at the same time. The
run times for each eight-well-pair model with MSW were reduced from several
days to an average of 18 hours. The simulation runs covered 11 years of SAGD
production, with an additional 3 months for preheating via steam circulation.
This industry-leading approach was more comprehensive than
single-well-pair modeling, and the testing helped avoid steam chamber quenching
while maximizing recovery.
Pilot design modifications to maximize recovery. Five
development scenarios were modeled to analyze the Lindbergh pilot design.
Sensitivity analysis results were extremely useful in optimizing the design.
Subsequent modification further maximized recovery while reducing SOR. The best
case of each scenario was taken to run the remaining sensitivities.
The right horizontal spacing is essential for maximizing oil recovery
and balancing SOR. Inter-pair horizontal spacing was evaluated at increments of
80 m, 100 m, and 120 mresulting in an optimal interval of 100 m, with
eight well pairs generating the most economically viable operation. Testing
injector and producer vertical well spacing allowed Pengrowth to determine the
best spacing for ultimate recovery. Spacing was tested using separation
increments of 3 m, 4 m, 6 m, and 7 m. The greater the vertical separation
between the injector and the producer wells, the higher the overall recovery,
but the lower the initial production rates. The increase in reserves was
incremental, and the original design of 5 m separation was within the
The number of injection points required to maximize recovery and
minimize SOR was also investigated. The final simulation cases used several
injection points, one point at the heel and five points spaced out in 25%
increments along the horizontal length. Two injection pointsat heel and
toeprovided maximum recovery.
Maximized recovery and minimized SOR
This study shows that additional sensitivity analyses and uncertainty
quantification are required to optimize the SAGD process under varying
reservoir conditions. Geology plays a key role in dictating SAGD performance
and must be adequately reflected in the simulation model. A detailed wellbore
model is critical in understanding pressure and heat transfer effects on steam
chamber formation. The ECLIPSE Thermal simulator and Multisegmented Well option
provided the rigor to determine the best operational parameters, maximizing
recovery and minimizing SOR. Pengrowth plans to introduce detailed
heterogeneity into the model for further studies.
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