Fishhook wells / Drilling uphill

Hi all,

Unlocking oil patches from offshore brownfields requires thinking out of the box, and fishhook-shaped wells where oil reservoir is drained with an hole angle greater than 90 degrees might be one of the solutions.

A project will be to drill minimum 6in (or 8 " if achievable) drain, building from 45° at the previous casing shoe, to 105-120° at the reservoir entrance to the toe. 500m-long openhole to be completed with perforated liner or with screens depending on the findings.

May I ask to the community experts to share their experience and/or any guidelines for this type of drilling - amongst the questions we think of:

1. What is the maximum BUR (or minimum radius of curve) that you have designed the well to reach the final inclination?
2. Have you run PDM or RSS BHA?
3. How many BHAs have you run (one to build, one for the slant) ?
4. If PDM was the prime choice, was it based on directional work to achieve the DLS/curve, or drillstring fatigue reduction by preferring sliding, or ”¦
5. Any particular BHA features (flex joints, articulated Any advice for the drillstring min specs (yield strength, conns, inspection periods”¦)
6. Bit selection altered by drilling uphill?
7. Have you preferably used NABM or WBM?
8. What are the drilling parameters & practices that you need to pay attention differently from standard drilling (mud ppties, hole cleaning, connection practices, WOB transmission (HWDP position) buckling avoidance”¦, tripping practices (backreaming with no brainer?)”¦)?
9. What are the criteria / rule of thumb for minimum UCS to drill uphill? any geomechanical criteria to closely look at?
10. Have you drilled uphill formations prone to severe/total losses? Any recommendations in such situation?
11. In your project have you found easier to drill bigger(8 ") rather than smaller (6in) hole size when drilling uphill?

That is obviously an non exhaustive list, but wanted to learn what did you find different and difficult to tackle when drilling uphill / fishhook wells.

Thanks in advance for the contributions.

L de Crevoisier
Perenco - SDE

11 Answer(s)

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