Tubular expansion tool and method

#The present invention relates to equipment and techniques for radially expanding a downhole tubular in a well. More particularly, the present invention relates to a downhole tool for rotating a bit at the lower end of the tubular and thereafter moving an expander axially downward to expand the tubular as slips maintain tool outer sleeve secured to a lower portion of the tubular.

#Various types of downhole tools have been devised for radially expanding a tubular. In many applications, the expander is moved axially through the tubular in direct response to fluid pressure acting directly on the expander. Tools of this type are disclosed in U.S. Pat. Nos. 6,631,759, 6,857,473, 6,892,819, 6,976,541, 7,021,390, 7,055,608, and 7,077,211 and U.S. Publication 20040231855. Tools that pump the expander upward conventionally use an expander receiver housing with an enlarged diameter that frequently presents significant problems when positioning the receiver housing in the lower end of a well.

#In other cases, a downhole tool utilizes a hydraulic section including a plurality of pistons connected in a series for axially moving the expander, as disclosed in U.S. Pat. Nos. 6,763,893, 6,814,143, 7,225,880, and 7,278,492. Expansion from the lower end of the tubular upward to an upper end of the tubular is disclosed. If desired, the tool may be collapsed and returned to the surface through the unexpanded upper portion of the tubular.

#FIG. 1 is a cross-sectional view of an upper portion of the tool including the shear ring.

#FIG. 2 illustrates a central portion of the tool shown in FIG. 1, including an expander powered to move axially downward to expand a tubular.

#FIG. 3 illustrates the central portion of the tool shown in FIG. 1, with the telescopic joint in an expanded position.

#FIG. 1 discloses an upper portion of a suitable tool 10 including a mechanism discussed below for controlling premature operation during running or drilling operations. As shown in FIG. 1, the tool may be suspended in the well from drill pipe or work string 11, which supports both an inner tool mandrel 12 and an outer tubular 14. Threads 13 connect the outer tubular 14 to upper bushing 15. As shown in the lower portion of FIG. 1, an inner piston 16 is also connected by threads 17 to the mandrel 12, and is sealed to the outer tubular 14 by one or more o-ring seals or packing 26. Outer piston 18 is threaded at 19 to the outer tubular 14, with seal 29 sealing with the mandrel 12. A plurality of outer pistons and inner pistons are provided for serially powering the tool. The mandrel 12 is threaded at 22 to work string 11, and is sealed at 21 to the work string 11. Fluid pressure within the work string may pass through a port 25 (shown in the lower portion of FIG. 1) in the mandrel 12 (which is functionally an extension of the work string 11) to axially separate an outer piston 18 connected to outer tubular 14 from an inner piston 16 connected to inner work string 12, thereby providing the axial force to hydraulically actuate the tool. A vent port 24 in the outer tubular 14 may accommodate axial separation of the pistons during this operation. Those skilled in the art will appreciate that a series of inner and outer pistons may be provided, with a number of selected pistons depending upon the desired axial force to be exerted on the expander and the permissible working pressure within the work string 11. Further details regarding a hydraulically powered downhole actuator for both setting the tool in the well and expanding the downhole tubular are disclosed in U.S. Pat. Nos. 6,622,789 and 6,763,893.

#A respective inner and outer piston may be axially connected when the tool is run in the well, and this connection broken after the drilling operation when the pistons separate to supply hydraulic power to the tool. Still referring to FIG. 1, sleeve 23, which acts as a stop, may be threaded to the lower end 20 of work string 11. During make-up of the assembly, connecting sleeve 28 may be positioned over the sleeve 23, and the threads between the sleeve 28 and the bushing 15 made-up so that the shoulder on the sleeve 28 engages the top end of the stop sleeve 23, thereby axially interconnecting the bushing 15 with the outer tubular 14. In a similar manner, the same components may be used to initially connect an outer piston and an inner piston. The sleeve 28 may include a recess, cut, or similar member reduction to desirably weaken the axial holding force of the sleeve 28, so that separation will occur at the location of the cut 27. Hydraulic force subsequently applied between the inner and outer pistons will thus shear the sleeve 28 at cut 27. The sleeve 28 effectively acts as a shear ring to prevent premature actuation of the tool. By keeping the pistons connected when the tool is run in the well, the likelihood of sand or debris getting trapped in the cavity between pistons is minimized. This cavity may also be filled with grease to prevent entry of sand or other solids between the pistons.

#FIG. 2 discloses a central portion of a suitable tool for both conducting a casing drilling operation and for thereafter expanding the liner internal diameter to greater than its run-in internal diameter. FIG. 3 discloses substantially the same portion of the tool when stroked to expand the liner. The tool may be used for drilling a portion of a well by powering a bit at a lower end of the casing (or liner), then expanding that same casing or liner while downhole in a well.