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Too much fluctuations in RPM trend
15 March 2020
We drill 6’’ hole at the depth of 6500 m. we are facing a lot of RPM fluctuations (80 – 110) goes to 110 and than drop to 80 with slightly change or near to constant torque limit to 10 KFT-LB. we have get same curve RPM trend even at low weight (3 – 4 tons) When we checked off btm Torque we have smooth curve of torque and RPM limit. This well have in slightly S shape with 2 side track. Formation is 100% shale. Please share your though how we minimize this issues. We use semi packed BHA.
2 answer(s)
Drilling Services Consultant
Clyde Drilling
Total Posts: 13
Join Date: 05/11/14
Have you modelled your T&D? and does the real world data compare well with the modelled data?
If not you have to investigate and find out why.
Minimise your BHA as far as possible- eg bit/ motor - turbine, with stab/ and top stab, (all stbs need to be UG) a few flexi NMag collars and some HWDP, that is all you should need for 6in hole.

Is your drilling mud in good shape? Have you added any lubricant to the mud? Have some available, and maybe try it

S Shaped wells can cause all sort of T&D problems
Drilling Specialist/Well Engineer/Training Consultant
Kingdom Drilling
Total Posts: 445
Join Date: 10/01/05

In regard to fluctuating RPM and torque resulting only when on bottom drilling? 

is this trend resulting all the time on bottom? 
Are you observing variance with formation changes?
If so.

Likely a bit type, style and design issue that relates and interacts with formation types and characteristics as drilled. Because RPM and torque is relatively smooth when off bottom. 

Torque response to WOB at various weight to formation types  is key.

Where I wold gather all data and ask a bit company to analyse  well's data as drilled to suggest bit design changes and reasons provided for such recommendations. 
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