Definition
Whipstock — A whipstock is a wedge-shaped deflection tool set in a wellbore that forces the bit or mill to one side, deflecting it into the wall to kick off a sidetrack or start a directional hole at a controlled toolface.
Also known as: whipstock, whip stock, deflection wedge
What a whipstock does
A whipstock is a long steel wedge with a concave, inclined face. When set and anchored in the hole, its ramp forces the bit or mill away from the wellbore axis and into the formation or casing wall, deflecting the new hole in a controlled direction. It provides a positive, mechanical kickoff for a sidetrack or the start of a directional well, oriented to a chosen toolface.
Types of whipstock
Open-hole whipstocks are anchored on bottom or against a packer, while cased-hole (casing-exit) whipstocks are set with an anchor and used with a milling assembly to cut a window through the casing — a procedure known as a casing exit or window mill. Retrievable and permanent designs exist. Correct orientation and firm anchoring are essential so the deflection starts the new hole in the planned direction with a manageable dogleg severity.
Why it matters for rentals
Whipstocks and their associated mills and anchors are job-specific tools used only during a kickoff or casing exit.
Rent whipstocks, mills, and steering tools from our downhole tools, or contact us to plan a sidetrack or casing-exit assembly.