Summary
Chemical enhanced oil recovery (EOR), including polymer and surfactant-based
processes, is a method that operators consider to maximize oil recovery from
onshore and offshore reservoirs. Because of the logistical, operational, and
environmental differences and the footprint and required weight needed for
additional injection and production equipment, offshore chemical EOR processes
are challenged by greater complexity and costs as compared with onshore
applications of the same technologies.
Chemical EOR commonly requires large volumes of injection chemicals, as well
as demulsifiers to break produced-water/oil emulsions and inhibitors to control
scale, resulting in high shipment and storage costs. The use of seawater and/or
produced water for injection of the chemicals into offshore fields mandates
stringent processing of both streams to allow optimal injectivity, sweep
efficiency, and chemical effectiveness in the reservoir. Offshore production of
saleable oil and clean water requires space- and weight-efficient
oil/water-separation euipment. Currently, conventional methods for processing
produced fluids fall short in both efficiency and compactness. High offshore
drilling costs lead to relatively large well spacing and more difficulty in
monitoring the EOR subsurface process, and lead to restrictions on the number
of disposal wells. Finally, environmental restrictions limit the overboarding
of toxic or poorly biodegradable EOR chemicals.
The industry is currently investigating the limiting factors pertinent to
offshore chemical EOR. As a result of these efforts, new enabling chemistries
and technologies are being examined for improving surface operations to allow
cost-effective offshore chemical EOR to be performed in an environmentally
sound and safe manner. Some of these recent chemical- and fluids-processing
developments are described in this paper. Subsurface challenges to implementing
offshore chemical EOR are also highlighted, along with potential solutions.
© 2012. Society of Petroleum Engineers
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History
- Original manuscript received:
21 January 2011
- Meeting paper published:
3 May 2011
- Revised manuscript received:
7 September 2011
- Manuscript approved:
14 October 2011
- Published online:
1 August 2012
- Version of record:
7 August 2012
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