Patent Application
20140096947
The field of the invention is cutting a pulling tools and more particularly tools that extend a cutter blade by rotation about a fixed pivot location to a flush support for the blade in an extended position so that the string above the cut can be raised for support from a rig floor to allow retraction of the blade and cutter removal through the cut tubular.
Cutting tools in the past were run with spears so that the cut tubular string could be retained by the spear and then pulled out of the hole. The cutter designs were variable and many included blades that extend by sliding down a ramp and turning about a pivot that was driven by a piston that was fluid driven and a spring to retract the blades. Some examples of such designs are U.S. Pat. Nos. 5,791,409; 2,136,518 and 2,167,739. Other styles for cutting tubular strings are illustrated in U.S. Pat. Nos. 7,823,632; 5,018,580; 4,856,642 and 5,014,780.
The present invention addresses several issues in the prior design and presents a more reliable and economical design. The actuating piston is flow actuated to shift and extend the cutting blades and to retain the extended blade position even after the flow is cut off. The blades are retracted with pressure on a landed plug on the piston so that a return spring is not required. The reverse movement of the piston shears out the body lock ring that had previously held the piston on the blade extended position. When the blades get through the wall of the tubular string being cut the adjacent housing squarely supports the blades that are extended radially so as to better support the cut string with reduced stress on the blades as the cut string is raised up to the point where it can be supported from slips on the rig floor so that the blades can be retracted after slacking off weight and pressuring up against a bumped plug on top of the piston. These and other features will be more readily apparent to those skilled in the art from a review of the description of the preferred embodiment and the associated drawings while recognizing that the full scope of the invention is to be found in the appended claims.
A cutting and pulling tool has a piston responsive to flow therethrough with an orifice to create backpressure to drive the piston uphole to rotate the blades outwardly such as in an expanded section of tubular below a transition from a smaller tubular dimension. The extended cutters are pulled to the transition and an overpull determines that the desired location has been reached. The overpull force is removed and fluid flow and rotation is commenced to cut. The blades extend to a position perpendicular to the tool axis so that they are supported off a radial housing surface as the weight of the cut string above is supported on the blades. The string is pulled up and supported with slips on a rig floor at which point weight is slacked off and a plug is landed in the top of the piston to push it down to remove the tool.
The cutting and pulling tool 10 has a top sub 12 with thread 14 to which is attached a work string that is not shown that extends to a well surface also not shown. Below the top sub 12 is a body 16 that has a centralizer assembly 18 on the outside and a piston assembly 20 internally in passage 22 that starts at thread 14 and continues into the bottom sub 24. Additional tools can be attached at thread 26 as needed.
A plurality of pivoting blade assemblies 28 are preferably arranged at 120 degree spacing for a total of three although other spacing and blade counts can be used. Each blade assembly has a fixed pivot axis about a pin 30. Each blade has an arcuate cutting edge 32 with opposed parallel surfaces 34 and 36 flanking the cutting edge 32 as better seen in
It should be noted that in the preferred application the blade assemblies 28 are actuated outwardly in a larger tubular portion 50 that has been expanded relative to the unexpanded portion 52 that is above with a transition 54 in between which is where the cut is to take place. As shown in
Once the
Those skilled in the art will appreciate the various advantages of the present invention. The piston is actuated with fluid flow to extend the blades but the flow need not be maintained to keep the blades extended as a lock ring selectively holds the blades extended to make the cut. There is no return spring. Reverse piston movement occurs preferably with a dropped plug into the passage in the piston followed by pressuring up to break the shear pin or pins on the lock ring or rings so that the blade assemblies are retracted with piston movement in the downhole direction. By the time the blade assemblies finish the cut the blades are extended approximately 90 degrees to the axis of the tool so that the severed tubular string lands squarely on a radially oriented surface while the window associated with each blade assembly has a radial bottom surface on which a flat surface on the blade assembly bottoms lands so that the loading on the blade assemblies is in the axial direction with little if any radial loading component.
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:
