Patent Grant
8863851
The field of the invention is a retainer for a downhole packer that is milled out so that the packer can be retrieved once sufficiently milled.
There are occasions where packers or other tools need to be milled out and yet portions of the tool need to be retained from falling in the hole once enough milling has gone on to release the packer or other tool. In the past such tools have been advanced into the packer bore or an extension to such a packer bore and included a grapple that was forced into the bore. If the packer let go the grapple was cammed outwardly by a series of inclined surfaces with such camming being triggered by the released weight of the remaining packer. The mandrel could be picked up and turned to the right to engage ratchet teeth so that a left hand thread is engaged to allow rotation of the grapple gripping member with respect to the packer bore for a release, if necessary. One such prior design is shown in Streater U.S. Pat. No. 6,681,858.
Streater uses a longitudinally split cylindrically shaped grapple member 106 that rides in a wedge 104. Grapple 106 has a groove 126 through which extends a tab 110. The groove and the tab are in the middle of the cylinder shape with the tab not extending as far out of the groove so that it stays clear of the packer bore. The problem with this design is during an attempt to release the packer by engaging teeth 124 and 134 while rotating to the right. As the grapple 106 which has an exterior left hand thread starts to come out of the packer bore while having torque transmitted into it through tab 110, some of the grapple 106 is still in the packer bore while the tab 110 transmits torque through slot 126 to the remainder of the cylindrically shaped grapple member now free of the packer bore and less resistant to applied torque. What can happen is that a shear failure can occur at the grapple which, in turn, results in getting the whole tool stuck with the part milled out packer.
The CK Packer Milling Tool sold by Baker Oil Tools is a peripheral mill that supports an internal wash pipe that has a grapple at the end. The mill is circulated through the wash pipe and the existing flow picks up cuttings for the return trip to the surface in the annulus. The small clearance between the mill housing and the wash pipe will not allow reverse circulation with cuttings into the mill housing to work nor can this design be simply modified to create a flow passage big enough between the wash pipe and the mill housing to accommodate the mill debris. The Washover Drill Collar Spear also sold by Baker Oil Tools uses gravity to grip the released drill collars by combining slips at the ends of collet fingers driven out by a taper on a mandrel that falls with the drill collars. The slips grab a wash over pipe extending around the slips.
The present invention provides a grapple for a downhole tool being milled out where the grapple members are better supported in a removal attempt when turning to the right. In a preferred embodiment fingers with exterior wickers that form a left hand thread extend from a ring. The wedge assembly has a series of torque fingers that preferably span the length of the grapple wickers and preferable are disposed on opposed sides of the grapple fingers. The ramp adds force to rotate the grapple when it is turned to the right. A reverse circulation pattern is used with the mill to remove and capture cuttings through the mill body in conjunction with the grapple device. These and other features of the present invention will be more readily understood by those skilled in the art from a review of the description of the preferred embodiment and the associated drawings that appear below while recognizing that the appended claims are the full measure of the invention.
A grapple device is secured to a mill to allow relative rotation between them. The grapple has an outward bias to allow it to grip the packer bore or an extension from the packer. The mandrel has a wedge adjacent its lower end and torque fingers that fit between grapple segments when relative longitudinal movement occurs between the mandrel and the grapple assembly. The grapple assembly has a left hand thread so that it comes out of the packer if the mandrel engages the grapple assembly in a manner for tandem rotation. The torque fingers on the wedge on the mandrel support the grapple fingers over their length as rotation to the right removes the grapple assembly from the packer bore. Reverse circulation takes away the cuttings into the mill bore where they are separated from the reverse circulating fluid.
A mandrel 30 is connected to the mill 12 so that the mandrel is rotating as the mill 12 turns. A grapple assembly 34 shown rolled flat in
The fingers 38 are biased radially outwardly due to connectors 40 and the openings 44 between them. The bottoms 46 of fingers 38 are not only tapered as shown in
A shear pin 54 extends from bottom sub 50 to provide a surface signal that the packer bore or extension 10 has been found. A set down weight on mill 12 then breaks the shear pin 54 and the mandrel 30 and the bottom sub 50 continue a descent into the packer bore 10. Eventually the ring 36 is pushed against bearing 28 when the wickers 42 on fingers 38 get pushed into the bore 10 by continuing downward movement of the mill 12. When the blades 22 land on the bore 10 the downward descent is complete and the rotation of the mill 12 can start. At that time, the fingers 38 grip the inside of the bore 10 while mandrel 30 rotates with mill 12. There is a gap between mandrel 30 and ring 36 so that the packer bore is merely gripped by fingers 38 but is not supported until the packer itself is milled loose. Bearing 28 allows the mill 12 to turn while the mandrel 30 and the fingers 38 do not turn. There are two possible scenarios. The packer can break loose and start to fall or the milling can stop and the mill 12 can be raised to bring the bottom sub 50 under the fingers 38. Either way there is no relative rotation between the bottom sub 50 and the fingers 38. If the packer breaks loose, the fingers 38 that grip the bore 10 with wickers 42 allow the grapple assembly 34 to slide down mandrel 30 until the taper 48 gets under taper 46 so that the packer can be simply removed. On the other hand, if the milling is stopped and the mill is no longer turning, it is safe to pick up on it to move tapers 48 up to tapers 46 and fingers 52 into position to straddle fingers 38. At that point turning to the right will rotate the grapple assembly 34 while its fingers 38 are supported against being sheared by adjacent torque fingers 52. Since wickers 42 are a left hand thread, turning to the right should remove the fingers 38 from contact with the bore 10 so that the tool can be removed, if needed.
Those skilled in the art will appreciate that the fingers 52 continue to provide torsional support to the fingers 38 as long as any part of them still engage the bore 10. Additionally, the reverse circulation mill 12 when combined with the grapple assembly 34 allows efficient capture of cuttings in a cuttings separator located near the mill 12 where the fluid velocities with cuttings are still high. The grapple structure is more flexible for getting a grip and yet stronger when being forced out of the bore 10 with right hand rotation. The number of blades and access ports for cuttings can be varied. The shape and number of torque fingers 52 can be varied and other forms of torsional support is envisioned that continues to be effective as long as wickers 42 are in the bore 10. The shear pin 54 can also be some other form of surface signal that the bottom sub 50 has landed on the bore or extension 10. The sloping contact of surfaces 46 and 48 enhance the extraction force to the left hand thread made by wickers 42 when there is rotation to the right to release from the packer. Although a packer is the preferred application other tools with a top bore for grapple insertion can also be milled and recovered when they release from the surrounding tubular.
In some situations it may be advantageous to release from the downhole tool when its weight is otherwise supported downhole. Setting down weight moves ramp 48 away from ramp 46 to allow coming out of bore 10 with a pickup force.
The above description is illustrative of the preferred embodiment and many modifications may be made by those skilled in the art without departing from the invention whose scope is to be determined from the literal and equivalent scope of the claims below.
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|---|---|---|---|
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| Entry |
|---|
| Baker Oil Tools, Conventional Fishing Technical Unit, Washover Drill Collar Spear Brochure, Oct. 2003, p. 20. |
| Baker Oil Tools, Conventional Fishing Technical Unit, “CK” Packer Milling Tool Brochure, Oct. 2003, p. 6. |
| Van Steveninck, Eric, et al., “An Innovative High Strength Drill Pipe Mechanical Cutting Solution Using Coiled Tubing”, SPE 81742, Apr. 2003, 1-9. |
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| Number | Date | Country | |
|---|---|---|---|
| 20100181789 A1 | Jul 2010 | US |
