Summary
In 2004, the large Mangala, Aishwariya, and Bhagyam oil-fields were
discovered in the remote Barmer basin of Rajasthan, India. The fields contain
light, paraffinic crude oils with wax-appearance temperatures only 5°C less
than reservoir temperatures and in situ viscosities that range from 8 to 250
cp. As these were the first significant hydrocarbon discoveries in this part of
India, there were few analog performance data available. Development plans for
the fields are based on hot waterflooding to prevent problems with in-situ wax
deposition, with production startup expected in 2009.
This article presents some waterflood results from viscous-oil fields around
the world, benchmarks the expected performance of the newly discovered
Rajasthan fields to this database, and discusses several issues associated with
waterflooding viscous oils. Given that the Rajasthan oils have some properties
that might be considered "unusual" and potentially troublesome for
waterflooding and that there are no long-term production data or a history
match of waterflood performance in hand, these benchmarks were considered
important reality checks. In fact, fields with similar or much higher
viscosities are waterflooded routinely with excellent recoveries in Canada, the
USA, and elsewhere.
Introduction
Waterflooding is sometimes dismissed as an ineffective process for a
viscous-oil field, with development plans focused on more-exotic and -expensive
recovery mechanisms such as chemical or thermal processes. However, basic
application of Darcy’s law and fractional flow theory, combined with operations
that focus on production at very high water cuts, clearly shows that
viscous-oil fields can yield reasonably good ultimate recoveries under
waterflood.
© 2009. Society of Petroleum Engineers
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History
- Original manuscript received:
30 January 2008
- Meeting paper published:
4 March 2008
- Revised manuscript received:
12 May 2009
- Manuscript approved:
1 June 2009
- Published online:
28 October 2009
- Version of record:
28 October 2009
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