The recent decline in crude oil production has needed more subsurface explorations to sustain and increase oil production in Mexico. The Client has discovered high potential fields with wells around 7,500 m (24,605 ft) to 8,200 m (26,902 ft) with high pressure, high temperature and hard formation features.

On deep HPHT wells, many challenges have been identified for drilling and completion, which can lead to the execution of challenging operations for reaching the objective of the well.

It is common to sidetrack the wells due to geological or mechanical failures. In Mexico, around 430 jobs were performed successfully in large casing sizes such as 9-5/8", 11-3/4" and 13-3/8" onshore and offshore. What is uncommon is to sidetrack the wells in smaller casing sizes (9-5/8" and 7"), with non-conventional grades, such as TAC-140, which is only used in Mexico with the record of three unsuccessful jobs (two onshore wells and one offshore well) to this day.

The work presented here aims to share the process of opening a window in a dual casing in hard steel (TAC-140) in a very complex and challenging environment.

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