Baker Hughes Corporation

Evan G Lewis

Calvin J Stowe

Mohan L Soni

Steve Rosenblatt

Daniel R Hart

An assembly for milling a window in a tubular features a layout that keeps a restorative force normal to the whipstock slope acting on the window mill to help it track the whipstock ramp long enough for making an exit at the desired location. A string mill assembly is made long enough to allow such a restorative force to be created on the window mill as it advances down the ramp. The bearing or cutting structures on the string mill are positioned with respect to the window mill so that either the top of the string mill or at least the first bearing structure above the window mill presents at the top of the window as the window mill arrives at the position where it is desired that it make an exit. The lower bearing structure of the string mill also preferably has a rounded profile to facilitate its entrance on to the whipstock ramp without getting in a bind on the tubular wall adjacent the top of the window.

Exit window milling assembly with improved restraining force

A milling assembly can be delivered downhole on wireline. Once at the desired location, a processor extends centralizing and driving wheels to initially position the assembly. The assembly has a cutter end with one or more mills or cutters that can be selectively radially extended. The entire cutter end can be rotated in an arcuate manner over a predetermined range. One or more cutter can be extended at a time and driven. The wheels are driven either in an uphole or downhole direction at the same time the arcuate motion can take place. Using a processor, different shapes in a surrounding tubular can be made such as windows for laterals, a plurality of openings for production or interior locator surfaces to properly position subsequent equipment with respect to openings already made by the device.

Wireline supported tubular mill

A bottom hole assembly used for making a window in a tubular is modified to reduce tool joint stress in a connection above the topmost watermelon mill. A protrusion is located between the topmost watermelon mill and the next threaded joint uphole. Preferably, the protrusion height is not greater than the outside dimension of the largest watermelon mill. Preferably, the protrusion is located below the upset area in the tubular where the threaded joint is made up and about &#x2153; the distance downhole from the threads to the next adjacent watermelon mill.

Thread fatigue relief for tool joint

The whipstock face below the mounting lug is initially curved with a fairly long radius to protect the whipstock body initially. After moving down the minimally sloping curved face a transition to a greater angle is presented to increase the lateral forces on the window mill and to force the mill laterally to exit the tubular through the window. The transition after the curved portion is preferably to a flat inclined surface to the ramp bottom.

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Kingwood, TX, United States of America

Evan G Lewis