SPE Reservoir Evaluation & Engineering
Volume 16,
Number 1,
February 2013,
pp. 97-116
Summary
The First-Eocene heavy-oil reservoir (1E) in the Wafra field is a candidate
for steamflooding because of its world-class resource base and low-estimated
primary recovery. However, industry has little experience in steamflooding
carbonate reservoirs, which has prompted the staging of several 1E
steamflooding tests, the latest of which is the large-scale pilot (LSP) started
in 2009. To assist in facilities design, to help understand expected
performance in a very heterogeneous reservoir, and to provide input to
early-decision analyses, numerical thermal simulation was used to generate
probabilistic forecasts. When adequate pilot history was available, the model
was validated with probabilistic methods. The LSP model contained 1.5 million
cells, which allowed the maintenance of adequate resolution and proper boundary
conditions in the pilot area. Parallel computation enabled a probabilistic
workflow to be implemented with this large thermal model. In this paper, we
highlight the methodologies and inputs used to generate the probabilistic
forecasts and validate the model. Major results of this work include the
following: In contrast to many greenfield forecasts, the LSP forecasts were
conservative, likely because of the unique aspects of the forecasting
methodology, proper selection of uncertainty ranges, and the relatively high
density of input data for model construction; wide variations in production
metrics were forecast, indicative of a highly heterogeneous reservoir; results
indicated that the validated model adequately captured the global or
statistical pilot heterogeneity, enabling proper capture of steamflood
flow/drainage mechanisms; and despite this heterogeneity, forecast oil-recovery
levels were comparable with those observed in steamfloods in sandstone
reservoirs.
© 2013. Society of Petroleum Engineers
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History
- Original manuscript received:
7 November 2011
- Meeting paper published:
12 December 2011
- Revised manuscript received:
31 October 2012
- Manuscript approved:
10 December 2012
- Published online:
1 February 2013
- Version of record:
27 February 2013
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