This question was also posted on a different forum, and Tom Kirkman tagged me and asked if I knew anyone who could help. I received a great response from Stewart McGregor who's the Senior ERD Engineer and Technical Development Manager at Merlin ERD.
The answer has been posted there, and I'm pasting it here to help others in the future:
Hope this is what your poster is looking for. Let me know if there’s follow up required. It’s more high level, rather than an explanation on torque, drag and hydraulics.
There’s no magic bullet to the drilling of the really long wells and no downhole tractors for drilling (yet – but they are in development), only a process of detailed data analysis, optimization and close management during operations.
Some bullet points on specifics. You’ll need:
- a thorough understanding of the surface loads (torque, drag and hydraulics) which will be imposed before drilling starts and the knowledge your equipment can handle them (and where the risks lie),
- a wellbore stability model that gives a detailed understanding of the mud weights required (according to the trajectory) to avoid problems with hole collapse and losses,
- a lithology column which can support the difference between static mud weight and ECD,
- a high pressure mud circulating systems (7500psi) - probably,
- rotary steerable systems and optimized drill bits - probably,
- drill pipe sized for connection torque requirements, buckling, ECD and hydraulics management,
- light weight BHA’s to reduce drag as much as possible,
- mud systems with additives to improve lubricity,
- a process to understand how clean your hole is while drilling so you can proactively manage hole conditions to avoid drilling and tripping problems in the first place.
The problem that Douglas posed, is actually a cornerstone of the business for MerlinERD who design, deliver horizontal, extended reach, and complex high angle wells. They also run courses to teach others to do the same. You can probably guess what the ERD stands for, but to find out about the Merlin bit, you'd have to hire them or attend a seminar :)