Wells – Expansible anchor or casing
Reexamination Certificate
2000-03-02
2001-11-20
Suchfield, George (Department: 3672)
Wells
Expansible anchor or casing
C166S242100, C166S243000
Reexamination Certificate
active
06318462
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a tool for threading onto and preventing rotation of a tubing string or progressive cavity pump in the bore of a casing string.
BACKGROUND OF THE INVENTION
Oil is often pumped from a subterranean reservoir using a progressive cavity (PC) pump. The stator of the PC pump is threaded onto the bottom of a long assembled string of sectional tubing. A rod string extends downhole and drives the PC pump rotor. Large reaction or rotor rotational forces can cause the tubing or PC pump stator to unthread, resulting in loss of the pump or tubing string.
Anti-rotation tools are known including Canadian Patent 1,274,470 to J. L. Weber and U.S. Pat. No. 5,275,239 to M. Obrejanu. These tools use a plurality of moving components, slips and springs to anchor and centralize the PC Pump stator in the well casing.
Further, the eccentric rotation of the PC Pump rotor imposes cyclical. motion of the PC Pump stator, which in many cases is supported or restrained solely by the tool's slips. Occasionally a stabilizing tool is added to dampen or restrain the cyclical motion to failure of the anti-rotation tool.
SUMMARY OF THE INVENTION
A simplified anti-rotation tool is provided, having only one moving part but which both prevents rotation and stabilizes that to which it is connected. In simplistic terms, the tool connects to a PC Pump or other downhole tool and upon rotation in one direction, causes a jaw to pivot radially outwardly from the tool housing to engage the casing wall and to arrest tool rotation. This action causes the tool housing to move oppositely and come to rest against the casing opposing the jaw. The tool housing and the downhole tool are thereby restrained and stabilized by the casing wall.
In a broad apparatus aspect, an anti-rotation tool comprises: a tubular housing having a bore and having at least one end for connection to a downhole tool and a jaw having a hinge and a radial tip, the jaw being pivoted at its hinge from one side of the housing, the jaw's pivot being offset from the jaw's center of gravity so that the jaw is pivotable upon rotation of the tool between a first position stowed against the housing for permitting movement within the casing, and a second position wherein the radial tip swings outwardly from the housing to engage the casing for arresting tool rotation and forcing the housing against the casing opposite the jaw.
Preferably, the profile of the jaw and the profile of the tubular housing are complementary so that the jaw does not project significantly from the housing during movement. Preferably, the jaw is arranged for tools having normal threaded connections wherein the jaw is actuated to the stowed position by counter-clockwise rotation of the tool and to the casing-engaging position by clockwise rotation of the tool.
More preferably, the jaw is formed separately from the housing so that the housing and bore remain independent and the bore can conduct fluid.
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patent: 4811785 (1989-03-01), Weber
patent: 4886130 (1989-12-01), Evans
patent: 4901793 (1990-02-01), Weber
patent: 5275239 (1994-01-01), Obrejanu
patent: 5623991 (1997-04-01), Jani
patent: 5636690 (1997-06-01), Garay
patent: 5909770 (1999-06-01), Davis
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patent: 1274470 (1990-09-01), None
Conelly Financial Ltd.
Goodwin Sean W.
Suchfield George
LandOfFree
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