Casing exit systems are used to sidetrack a
wellbore for many reasons, including re-entry of an existing wellbore, drilling
a bottomhole assembly that has become stuck and is too costly to fish out,
severe formation or drilling problems, the need to change the direction of a
wellbore, or the need to drill multiple exits from a single wellbore.
Big Rig one-mill casing exit system is
retrievable and has two retrieval tool options to accommodate severe hole
conditions. A complete system includes a whipstock combination, an orientation
device, an anchoring device, and a milling tool. This system provides a quicker
kickoff with a higher build rate in short-radius drilling applications. Decreased
length of the whipstock and a milling assembly consisting of only one multi-section mill form a significantly shorter window exit bottomhole assembly
(BHA). The reduced-length BHA is capable of passing through higher doglegs in
the wellbore. Our whipstock system provides an effective means to exit casing
and provide a window to run drilling BHA, liners, and completion equipment
through.
Big Rig field-proven special taper box tap
engages the retrievable whipstock so it can be released from the wellbore. It
is specially threaded inside the bottom section to match the taper tap of the
whipstock and it will not damage the whipstock face during retrieval. Two Big
Rig products can be used to recover a retrievable whipstock: the fixed lug and
the special taper box tap. Big Rig recommends using the releasable fixed
lug retrieval tool (FLRT) as the primary method of the retrieving a whipstock.
In the rare case that the FLRT cannot be used, the special taper box tap is a
viable option. The recommended bottomhole assembly for whipstock retrieval
includes the special box tap, safety joint, jars, and drill collars. The tool
is engaged with a combination of set-down weight and rotation. The final step
is to apply the torque several times to help ensure a good hold on the
whipstock.