Use of New Hydrostatic Packer Concept To Manage Lost Returns, Well Control, and Cement Placement in Field Operations
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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. Copyright © 2009 Society of Petroleum Engineers.
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