Summary
The performance of many waterfloods [and enhanced-oil-recovery (EOR)
schemes] is characterized by fluid injection under fracturing conditions.
Especially when the geology is complex and the mobility of the reservoir is
low, induced fractures can be of the same order as the well spacing, which has
a significant (in general undesired) impact on both areal sweep and vertical
conformance. Therefore, fluid injection needs to be actively managed and
surveyed in order to design an appropriate injection strategy over time.
We have analyzed historical injection/production-test, injection
step-rate-test, and falloff (FO) test (FOT) data of an existing complex
waterflood in the Pierce field, North Sea. The mental subsurface model that
emerged from this data analysis was developed further through a series of
dynamic fracture-propagation simulations. While the data analysis was a
relatively standard procedure, the fracture-modeling part was far from trivial
and included simulations using a standalone fracture modeling tool and a more
sophisticated coupled dynamic fracture-propagation reservoir simulator, both
being in-house software tools.
The combined analysis was used to develop a better understanding of the
waterflood performance. The main improvement compared to previous work was the
integration of the data analysis and the dynamic modeling work rather than
looking at each data source individually. In combination, a consistent
explanation of the observed reservoir behavior was achieved. This has resulted
in changes in the day-to-day water injection management and is expected to play
a key role in longer-term development strategies.
© 2010. Society of Petroleum Engineers
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History
- Original manuscript received:
31 October 2008
- Meeting paper published:
3 December 2008
- Revised manuscript received:
20 February 2009
- Manuscript approved:
27 February 2009
- Published online:
16 February 2010
- Version of record:
24 February 2010
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