Summary
The cold-production-recovery process, also known as cold heavy-oil
production with sand (CHOPS), is a method for enhancing primary heavy-oil
production by aggressively producing sand. It is successful in vertical (or
slanted or deviated) wells in western Canada. In this process, large amounts of
sand are produced on a continuing basis along with heavy oil. Attempts at cold
production in horizontal wells have not been particularly successful. When sand
production has been generated in horizontal wells, these wells have tended to
become plugged with sand.
This paper presents the results of experiments performed to assess the
feasibility of applying cold heavy-oil production in horizontal wells that have
been completed with slotted liners using less-aggressive (i.e., managed)
sand-production strategies. Specifically, the effects of slot size, confining
stress, fluid velocity, and sand-grain sorting on sand production were
investigated.
The results indicate that slot-size selection is critical for establishing
"sand on demand." From the experiments, a correlation between slot size and
controlled sand production was found for well-sorted sands. This correlation
should allow for the specification of appropriate slot sizes for target
reservoirs containing well-sorted sands.
In the experiments, when flow rates resulted in low but persistent sand
production, channels and/or elliptical dilated zones were created that greatly
enhanced the effective permeability near the slot. This observation suggests
that producing at low and steady sand cuts for a long period of time might
bring two benefits: a way to transport the sand out of the well without causing
plugging and the creation of high-permeability channels or zones that can
improve production from the reservoir.
To summarize, if the appropriate slot size were combined with the right
drawdown rates, controlled sand production could be achieved, with attendant
significant increases in permeability. This suggests that substantially
increased oil-production rates could be achieved from horizontal wells if
sand-production rates could be maintained at low but persistent levels.
© 2012. Society of Petroleum Engineers
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History
- Original manuscript received:
8 April 2010
- Meeting paper published:
28 May 2010
- Revised manuscript received:
8 February 2012
- Manuscript approved:
8 March 2012
- Published online:
4 September 2012
- Version of record:
6 December 2012
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