Schlumberger

Case Study: First Openhole Sidetrack with Low-Side Exit through Existing Window Onshore Mexico

TrackMaster OH system allows sidetrack in 64° inclination well at a temperature of 142 degC, achieved in single trip

Challenge: Perform first openhole sidetrack with a low-side exit through an existing casing window in 64° inclination well at 142 degC.

Solution: Run TrackMaster OH system wellbore departure system with a specially modified whipstock, to maximize probability of success.

Result: Planned and executed the sidetrack successfully in one trip.

Low-side exit sidetrack required in open hole

A PEMEX operation drilling on land in Mexico required a sidetrack with unusual conditions. The sidetracking assembly had to pass through an existing casing window, the top of which was located at 5,872 m. The assembly then needed to be oriented to achieve a low-side exit. A FasTrack one-trip mill had previously milled the window and drilled the rathole in less than 2.5 h. the formation is 80% dolomized mudstone and 20% mudstone with and unconfined compressive strength (USC) of 27,000 psi. The existing well was highly deviated with a 64° inclination, and the temperature at the sidetrack depth was 142 degC.

TrackMaster OH system customized for the operation

A 7-in TrackMaster OH openhole whipstock and sidetracking system was employed, set up to provide an openhole whipstock and anchored by an expandable anchor. The whipstock ramp section was specially modified according to a Schlumberger design with a record of successful low-side exits in cased hole in the North Sea.

Sidetrack in highly deviated well accomplished through existing window

The TrackMaster OH assembly successfully passed through the casing window. It was oriented with the help of MWD equipment for a low-side exit by rotating it 90° to the right, and then anchored in open hole at 5,939 m with the expandable, hydraulically set three-point anchor. With precise control of the kickoff depth and orientation, the 6-in sidetrack was accomplished flawlessly in a single trip, the first low-side exit performed in open hole.


Download: First Open Hole Sidetrack with Low-Side Exit through Existing Window Onshore Mexico (0.66 MB PDF)

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Trackmaster OH System

Trackmaster OH
Whipstock specifically modified to maximize probability of success.