Summary
A hydrostatic packer consists of a column of light fluid pumped into the
annulus or drillstring to cause the total hydrostatic head to be equal to or
less than the integrity, which is a product of the fracture-closure stress
(FCS). This result is positive surface pressure, which allows accurate
placement of cement, lost-returns treatments, or other fluids in situations
where they would otherwise be overdisplaced if a full column of drill-weight
mud were used. Although hydrostatic packers are not a physical device, they are
referred to as packers because they serve many of the same functions as
retainers and squeeze tools and are used in similar operational situations.
The operator has used hydrostatic packers in one area for 15 years and
globally for the last seven years. Despite the maturity of the practice, it has
not been adopted by the industry. The business value is large, but the lack of
understanding of fracture mechanics in the drilling industry raises a
significant barrier. The use of hydrostatic packers requires that engineering,
operations, and contractor personnel understand the fracture propagation
mechanism through which major lost returns events occur, and particularly the
role of FCS. The team must also develop field practices to mitigate specific
risks associated with hydrostatic packers. This paper discusses these points
along with the operational issues that must be considered in certain unique
situations.
The applications described include stabilizing the annulus following lost
returns, controlling placement of lost-circulation material (LCM) when pumping
pills, controlling cement placement during squeeze operations, achieving
high-quality cement coverage behind liners with lost returns, and management of
downward underground flow.
Hydrostatic packers have been used effectively in more than 30 fields and
have contributed greatly to the operator’s high success rate in treating lost
returns events (Dupriest 2005). Their use requires training and structured risk
assessment, but they are simple in concept and have been effective in
controlling fluid placement in all field applications to date.
© 2009. Society of Petroleum Engineers
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History
- Original manuscript received:
7 December 2007
- Meeting paper published:
4 March 2008
- Revised manuscript received:
29 September 2008
- Manuscript approved:
16 February 2009
- Published online:
13 October 2009
- Version of record:
23 December 2009
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