Chalk Drilling Performance
24 November 2006
Thanks for the great response for the BHI VertiTrak.
I know some of us probably are having a hard time in drilling the
Chalk in the central North Sea. For the best practice purpose, could
you please share some experience of what bit YOU ARE PROUND OF MOST
in your area with your BHA(powerdrive, Autotrack, PDM, etc)? I think
each bit company has very good bits. No Detail required, only to see
if there is a common in blades numbers, cutters numbers, cutter
Thank you again for sharing,
Does anybody have any experience of drilling chalk with a PDM v rotary BHA. What gives best performance. Is the chalk WOB dependant or RPM dependant? I plan to use a 12 1/4" PDC to drill 1000 ft of hard Ekofisk and Tor. All suggestions welcome.
PS Vertical well, directional control not required.
Senior Drilling Engr
I do not have any experience drilling in Chalk but I am agree that,
the 17 1/2" HCM607Z, 19mm, 8 Blades, EZSteer Technology, 6" Gauge
and Zennith Premium Cutters has the best performance in most of long
vertical interval attempts, in the 12 1/4'' section I can say the 12
1/4'', PDC Bit type FMR3663Z, 6 blades 13mm to 19mm Cutter was made
a good performance in the vertical hole compare with some other bits
If your well is direction or horizontal, you can play with the gauge
and cutter length
The Hughes HCM series bits are pretty well proven. Depends on the
hole size but for 17 1/2" hole we get excellent results with the
HCR609z and for 12 1/4" hole HCM607z. Depends alot on where the
chalk is regionally though- some chalk is just hard to drill
irrespective of bit used, chert streaks and pyrite stringers etc.
To plan for the worst case use a heavy duty back up like a DSX97 or
similar in reserve.