Wells – Processes – Placing or shifting well part
Reexamination Certificate
2002-01-09
2004-03-30
Bagnell, David (Department: 3672)
Wells
Processes
Placing or shifting well part
C166S050000, C166S117600, C166S242100, C166S348000, C166S380000
Reexamination Certificate
active
06712149
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to subsurface tools used in the completion of subterranean wells and, more particularly, provides an apparatus and method for use in spacing out tubular strings and components within a wellbore.
2. Description of Related Art
Hydrocarbon fluids such as oil and natural gas are obtained from a subterranean geologic formation, i.e., a reservoir, by drilling a well that penetrates a hydrocarbon-bearing formation. Once a wellbore has been drilled, the well must be completed before hydrocarbons can be produced from the well. A completion involves the design, selection, and installation of equipment and materials in or around the wellbore for conveying, pumping, or controlling the production or injection of fluids. After the well has been completed, the production of oil and gas can begin.
Typically, one of the final steps taken in the completion of a well is the running into the well of the production tubing. Once the production tubing is inserted into the well, the bottom of the tubing string may need to be located at a certain position in relation to other downhole equipment, such as being inserted into a polished bore receptacle of a packer that had been previously set. Just as the bottom of the tubing string needs to be located in a predetermined depth, likewise the top of the tubing string has to be located so as to properly “land” the tubing hanger within the wellhead. In order for both the top and bottom of the tubing string to be in their proper locations, the length of the tubing string is measured and controlled. This operation is called the “spacing out” of the well.
For wells drilled on land, the spacing out of the production tubing is a relatively simple task. The tubing is run into the well to the depth of the packer until contact with the packer is indicated by a decrease in the weight of the tubing string. At a predetermined “slack off” weight, the tubing is marked and measured. The upper joint of tubing is removed and replaced with one or more shorter tubing sections, often called “subs”, that will make the overall tubing string the length needed for the proper well space out. Since the wellhead, completion unit and personnel are located at the surface, the spacing out of the tubing string is usually a minor task.
On wells that are drilled offshore that contain a subsea wellhead, the operation of spacing out a well can be difficult. The wellhead where the tubing must be landed is located on the ocean floor, not where the rig and personnel are located. For wells being completed from fixed platforms, the distance from the rig floor to the wellhead can be measured and compensated for. One method is to run the tubing into the well until the required slack off weight is seen. Then rather than just the top joint being removed, the length of tubing from the rig floor to the wellhead on the ocean floor must be pulled to enable the proper space out to be made. After the proper adjustments are made and the tubing hanger is attached, the modified tubing string length will be run back into the well. For example, a well drilled in a water depth of 2,000 feet that needs an adjustment of 10 feet for proper space out, would require the pulling and subsequent re-running of the 2,000 feet of tubing, for a total handling of 4,000 feet of tubing. Alternately, the tubing hanger can be attached to the tubing string on the initial run into the well at a location that is estimated to be correct. If the location is within the variance of the downhole tool, such as the length of the polished bore receptacle, the tubing will not need to be pulled and adjusted. Using specialized tools, such as packers with longer than usual polished bore receptacles and tubing seal assemblies with extra length and multiple seals, will increase the possibility of success with this alternate method, but will also increase the material cost incurred.
Wells being completed from floating drilling rigs such as semisubmersibles or drillships pose additional problems. The “heave” of the floating rig, along with variations in the positioning of the rig over the well, results in the distance from the rig floor to the wellhead not being a fixed length (i.e., being a variable length). This length can vary by as much as three feet or more, depending on tidal and wave conditions, which can make the methods of spacing out mentioned above unworkable, difficult or time consuming to perform. The amount of heave can also vary depending on the age, design and level of sophistication of the rig positioning system. To compensate for the rig heave, additional equipment, such as expansion joints, sliding sleeves, extended seal assembly lengths and multiple seals have been employed.
There is a need for improved tools and methods to enable the proper spacing out of offshore wells.
SUMMARY OF THE INVENTION
One embodiment of the present invention is a system for use in spacing components within a wellbore. The system comprises a well casing comprising at least one profile, the profile capable of being positioned at a known location within the wellbore and adapted to indicate the location of at least one component inserted into the wellbore.
Another embodiment of the present invention comprises an apparatus for use in spacing out tubular strings within a well comprising a casing having an inner wall where the casing includes at least one profile disposed within the inner wall. A landing tool is linked to well tubing and is sized so as to seat within the profile. A tubing hanger is attached to the well tubing, the tubing hanger being capable of landing within a wellhead. When the landing tool is seated within the profile, the length of well tubing needed to land the tubing hanger within the wellhead can be determined. The tubing string can be inserted within the well. The distance between the wellhead and the profile can be known.
The casing can comprise an upper profile and a lower profile and the distance between the upper profile and the lower profile can be known. The landing tool and the upper profile are capable of being in a releasably seated configuration.
Yet another embodiment of the invention can be used for the spacing out of tubular strings within a well that comprises a casing having an inner wall, the casing comprising an upper profile and a lower profile. A well tubing is movable longitudinally within the casing and a landing tool is linked to the well tubing. The landing tool can comprise seating projections that are adapted to sequentially seat in the upper profile and the lower profile. The landing tool and seating projections can be adapted to reversibly seat in the upper profile, allowing movement of the landing tool in either an upward or downward direction. The landing tool, seating projections and lower profile can be adapted such that when the landing tool is seated within the lower profile, the landing tool is restricted from any movement in a downward direction but can be unseated from the lower profile and moved in an upward direction. The landing tool and seating projections can be adapted to release from the upper profile when a predetermined slack off weight is exceeded. When the landing tool is seated within the upper profile, the length of well tubing needed to space out the well tubing can be determined.
Still another embodiment of the invention is a method of spacing components within a wellbore. The method comprises providing a well casing comprising at least one profile and inserting at least one component within the wellbore wherein at least one component can releasably engage with the at least one profile. The effects of the engagement of at least one component with the at least one profile are observed and the amount of component movement required to obtain a desired component placement within the wellbore is determined.
An alternate embodiment of the invention is a method of spacing out a tubular string within a well having a wellhead. This method comprises providing a casing string located within the well, the ca
Leismer Dwayne D.
Wetzel Rodney J.
Bagnell David
Echols Brigitte Jeffery
Griffin Jeffrey E.
Schlumberger Technology Corporation
Trop Pruner & Hu P.C.
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