Wells – Processes – Disassembling well part
Reexamination Certificate
1998-12-04
2001-03-06
Lillis, Eileen D. (Department: 3673)
Wells
Processes
Disassembling well part
C166S065100, C166S242600, C166S384000, C166S385000
Reexamination Certificate
active
06196325
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to cableheads for coiled tubing logging operations, the cableheads having mechanical devices for releasing a stuck tool, and more particularly, to a cablehead which allows releasing of a tool when desired while preventing accidental and premature release of the tool.
2. Description of the Prior Art
In heavy-duty logging and/or perforating operations, the logging tool and/or perforating guns may be run into the well using coiled tubing electric line reels. This technique is used particularly often on deviated or horizontal wells. Typically, a cablehead is positioned between the end of the length of coiled tubing and the logging tool and/or perforating guns. The cablehead has a means for mechanically connecting the tubing to the tool or guns and also for providing an electrical connection between a logging cable run down the inside of the coiled tubing and the logging tool or perforating guns. Many of these cableheads also include a means for releasing the tool or guns in the event that the tool or guns becomes stuck in the well.
Prior to the present invention, most cableheads for coiled tubing logging operations have relied on mechanical disconnects to provide a means of releasing in the event of a stuck tool situation. With such a mechanical disconnect, the coiled tubing is generally released from the stuck tool or gun by applying a predetermined amount of tension on the coiled tubing, thereby breaking a set of shear pins in the cablehead. Once the shear pins are broken, the coiled tubing is removed from the well, and the stuck tool or perforating gun may be fished out on a subsequent trip into the well.
A problem with the prior art mechanical disconnect portion of these cableheads is that there is a tendency to accidentally shear during perforating operations. When the guns are shot in wells that are substantially horizontal, this is not much of a problem because the vertical, or axial, shock loading is substantially negligible. However, when a well is deviated at a shallower angle, for example 60°, a substantial vertical shock load component is created when the guns are fired. Often, this vertical shock load is enough to prematurely shear the shear pins in the cablehead. Obviously when this happens, the guns are released and left in the well unintentionally.
Another problem with the mechanical disconnect portion of these prior art cableheads is that there are limitations when the shear load for shearing the pins is selected. The natural tendency of a tool operator is to select shear pins with strengths that are very high in order to prevent accidentally releasing the tool or perforating guns when in the well. However, the tensile strength of the coiled tubing is also a factor which must be considered when making the shear pin selection. For example, in a deep well, the weight of the coiled tubing string hanging in the well may be so high that the available over-pull at the surface is limited to a few thousand pounds. If the operator pulls on the tubing string at a higher load than this, there is the risk of parting the tubing at the surface, thereby leaving the entire tubing string and tool in the well which, of course, is a very undesirable situation.
The present invention solves this problem by providing a locking means such as a set of lugs to securely lock the components of the cablehead together so that no loading is prematurely applied to the shear pins. The shear pins may only be sheared after fluid is pumped down the coiled tubing and pressure applied to actuate a piston in the cablehead to release the lugs so that a shearing force may then be applied to the shear pins. Thus, there can be no premature shearing as in prior art mechanical disconnects.
SUMMARY OF THE INVENTION
The present invention is a cablehead for use with coiled tubing electric line in well operations. The cablehead comprises a housing and an actuating piston slidably disposed in the housing. The housing comprises an upper housing adapted for connection to a length of coiled tubing, a lower housing adjacent to the upper housing, and a shearing means for shearably attaching the lower housing to the upper housing. The cablehead further comprises a locking means, disposed between the upper and lower housings, for preventing shearing of the shearing means when the locking means is in a locked position and allowing shearing of the shearing means by relative movement between the upper and lower housing when the locking means is in an unlocked position. The piston has a running position holding the locking means in the locked position and is movable to a releasing position allowing movement of the locking means to the unlocked position.
The cablehead further comprises biasing means in the housing for biasing the piston toward the running position thereof. In the preferred embodiment, the biasing means is characterized by a compression spring.
The housing and piston define a first flow path therein through which fluid may be circulated when the piston is in the running position. A nozzle is disposed across the first flow path for controlling a fluid flow rate therethrough. This nozzle is one of a plurality of interchangeable nozzles which may have various sizes of orifices or ports therein. This first flow path is closed when the piston is in the releasing position.
The housing also defines a second flow path therethrough whereby fluid may be circulated when the piston is in the releasing position.
The piston has a saddle thereon which is aligned with the locking means when the piston is in the releasing position thereof so that the releasing means may be moved inwardly into the saddle. The piston comprises an upper piston on which the saddle is located and a prop attached to the upper piston.
The apparatus may also comprise a spring rest disposed in the housing and a second shearing means for shearably attaching the spring rest to the housing. This second shearing means is sheared when the piston is moved to the releasing position thereof. In the preferred embodiment, the spring is engaged with the piston and spring rest and disposed therebetween.
The upper housing defines a recess therein, and the lower housing defines a lug window therein aligned with the recess. The locking means is characterized, in the preferred embodiment, by a lug disposed in the window and extending into the recess when in the locked position and spaced from the recess when in the unlocked position. The lug extends into the saddle on the piston when the lug is in the unlocked position.
The present invention also includes a method of releasing a wireline tool in a well. This method comprises the step of providing a cablehead for connecting the wireline tool to a length of coiled tubing. This cablehead may be said to generally comprise a housing having an upper housing connectable to the coiled tubing and a lower housing shearably attached to the upper housing and connectable to the wireline tool, a lug disposed in the housing for preventing shearing disconnection of the upper and lower housings when the lug is in a locked position and allowing shearing disconnection of the upper and lower housings when the lug is in an unlocked position, and a piston disposed in the housing and movable between a running position holding the lug in the locked position and a releasing position allowing the lug to be moved to the unlocked position.
The method further comprises the steps of running the coiled tubing, cablehead and wireline tool into the wellbore with the piston in the running position thereof, pumping fluid down the coiled tubing and applying pressure to the piston and thereby moving the piston to the releasing position, applying tension to the coiled tubing such that the lug is moved to the unlocked position substantially simultaneously with the upper housing being shearably disconnected from the lower housing, and removing the coiled tubing and the upper housing from the wellbore. The method may further comprise the step of fishing the lower housing and the
Connell Michael L.
Howard Robert G.
Tucker James C.
Halliburton Energy Service,s Inc.
Kennedy Neal R.
Kent Robert A.
Lee Jong-Suk
Lillis Eileen D.
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