Historically, extended reach offshore wells in Trinidad & Tobago were characterized by wellbore instability and hole cleaning challenges. These phenomena had become almost impossible to manage effectively in the highest angle wellbores, leading to levels of non-productive time (NPT) that threatened the economic viability of the latest development.

Wellbore instability exacerbated the hole cleaning challenge, fueled by a new instability mechanism at highest wellbore inclinations. This led to pack-offs and stuck pipe incidents. Additionally, poorly understood and generally insufficient hole cleaning practices increased stuck pipe risk, and also caused the equivalent circulating density (ECD) to rise, resulting in mud losses due to the narrow window between mud density required for wellbore stability, and formation fracture gradient.

The solution to these problems was found through advanced downhole measurements of borehole stability and hole cleaning, transmission of those data back to surface via a high frequency medium ("networked or wired" drill-pipe), deployment of subject matter experts into the rig team for critical phases of the operation, and introduction of unconventional drilling and decision-making practices to mitigate the problem phenomena.

This paper describes the transformational efficiency improvement that was achieved by this combination of new technology, improved workflows, and multidisciplinary expertise deployed to the rigsite. The methodology was implemented on the third well, resulting in a reduction of NPT from 47% and 48% on the first two wells, to 10% on the third, clearly expressing the enhanced control of these drilling phenomena on the third well.

Recommendations offered are relevant to many extended reach drilling campaigns, and may be critical to the success of ultra-ERD wells.

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