Schlumberger

Case Study: DRIL-FREE – Maintains Steady Drilling Torque While Building Angle to 90° With the SILDRIL System

Challenge:

The 12¼” Sections of the Blake Field are drilled in 2 parts. Initially a pilot hole is drilled to determine the Oil Water contact in the reservoir. The Pilot hole is plugged back and the12¼” Section kicks off building angle to horizontal in order to line up with the reservoir for the 8½” Section Drill-In Fluid.

Historically building angle to horizontal with a Silicate Mud System would be considered impracticable.

Solution:

M-I provided a lubricant “DRIL-FREE” capable of withstanding the high alkalinity’s of the SILDRIL System. Thus enabling the section to be drilled.

Extensive Lab Testing was done to discover the most effective Silicate Lubricant.

Result:

  • While kicking off the cement plug erratic torque was observed. 1% DRIL-FREE was added and the erratic torque smoothed out.
  • The concentration of DRIL-FREE was increased to 2% at 6,330 ft (73° inclination). At this point the torque varied from 11 to 18 kft/lbs.
  • Drilling continued building angle to 90° while drilling to TD of 6945 ft with no increase in torque. At TD the torque varied from 12 – 17 kft/lbs.
  • Pick Up and Slack Off weights also remained constant at 325 klbs and 240 klbs respectively.

Well Information
Location Blake Field, 13 / 24a-B1, North Sea
Completion Date July 2000
Section Total Depth 6,945 ft
Bottom Hole Temperature 130ºF
Maximum Deviation 90º
Mud System SILDRIL (KCl / Silicate WBM)

About DRIL-FREE

DRIL-FREE is M-I’s proprietary lubricant for the SILDRIL System. DRIL-FREE is a blend of esters and fatty acids originally designed as a lubricant but optimized to act as an anti-sticking agent (to minimize differential sticking potential on filter cakes).

DRIL-FREE can be used in concentrations ranging from 1% to 3%. Has an HOCNS category E and is therefore environmentally friendly.

DRIL-FREE Benefits

  • Effective lubricant for Silicate Fluids
  • Reduces torque increases as angle and inclination build to horizontal
  • Environmentally friendly – HOCNS “E” Category Reduced clean-up times

Download: DRIL-FREE – Maintains Steady Drilling Torque While Building Angle to 90° With the SILDRIL System (0.29 MB PDF)

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