Wells – Valves – closures or changeable restrictors – Fluid operated
Reexamination Certificate
2000-11-29
2003-03-18
Bagnell, David (Department: 3672)
Wells
Valves, closures or changeable restrictors
Fluid operated
C166S308400, C166S332100, C166S177500
Reexamination Certificate
active
06533037
ABSTRACT:
TECHNICAL FIELD
The invention relates to valves for use in wellbores.
BACKGROUND
After a wellbore is drilled, various completion operations are performed to enable production of well fluids. Examples of such completion operations include the installation of casing, production tubing, and various packers to define zones in the wellbore. Also, a perforating string is lowered into the wellbore and fired to create perforations in the surrounding casing and to extend perforations into the surrounding formation.
To further enhance the productivity of a formation, fracturing may be performed. Typically, fracturing fluid is pumped into the wellbore to fracture the formation so that fluid flow conductivity in the formation is improved to provide enhanced fluid flow into the wellbore.
A typical fracturing string includes an assembly carried by coiled tubing, with the assembly including a straddle packer tool having sealing elements to define a sealed interval into which fracturing fluids can be pumped for communication with the surrounding formation. The fracturing fluid is pumped down the coiled tubing and through one or more ports in the straddle packer tool into the sealed interval.
After the fracturing operation has been completed, clean-up of the wellbore and coiled tubing is performed by pumping fluids down an annulus region between the coiled tubing and casing. The annulus fluids push debris (including fracturing proppants) and slurry present in the interval adjacent the fractured formation and in the coiled tubing back out to the well surface. This clean-up operation is time consuming and is expensive in terms of labor and the time that a wellbore remains inoperational. By not having to dispose of slurry, returns to surface are avoided along with their complicated handling issues. More importantly, when pumping down the annulus between coiled tubing and the wellbore, the zones above the treatment zone can be damaged by this clean-out operation. Further, under-pressured zones above the straddled zone can absorb large quantities of fluids. Such losses may require large volumes of additional fluid to be kept at surface for the sole purpose of clean-up.
An improved method and apparatus is thus needed for performing clean-up after a fracturing operation.
SUMMARY
In general, in accordance with an embodiment, a tool for use in a wellbore comprises a flow conduit through which fluid flow can occur and a valve assembly adapted to be actuated between an open and closed position in response to fluid flow at greater than a predetermined rate.
Other features and embodiments will become apparent from the following description, from the drawings, and from the claims.
REFERENCES:
patent: 3361204 (1968-01-01), Howard et al.
patent: 3430701 (1969-03-01), Canada
patent: 4815538 (1989-03-01), Burroughs
patent: 5291947 (1994-03-01), Stracke
patent: 5295393 (1994-03-01), Thiercelin
patent: 5361836 (1994-11-01), Sorem et al.
patent: 5456322 (1995-10-01), Tucker et al.
patent: 6206133 (2001-03-01), Paulsson
Petro-Tech Tools, Inc. Technical Manual (1999).
Baker Oil Tools Packer Systems Catalog (1996).
Schlumberger Workover and Remedial Tools 2000-2001 Catalog (2000).
Costley James M.
Eslinger David M.
McGill Howard L.
Sheffield Randolph J.
Zemlak Warren M.
Bagnell David
Dougherty Jennifer R
Jeffery Brigitte L.
Kanak Wayne I.
Ryberg John J.
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