Performance Report: MEGADRIL System Saves 1.5 Drilling Days and $15,000 Average Per Well in North Dakota

Challenge: These wells needed the maximum hole stability of an invert-emulsion fluid for drilling an 8¾-in. interval through the water-sensitive Charles and Kibby Lime formations. Additionally, losses had to be minimized while drilling the Mission Canyon formation, chiefly through precise control of Equivalent Circulating Densities (ECDs) prior to setting 7-in. casing. The lateral section would then be drilled with brine through the Bakken Shale.

Solution: The MEGADRIL system has proven to be the fluid of choice on the continued Bakken-shale development for a major operator in the Williston Basin. The MEGADRIL system, using a one-drum emulsifier package, MEGADRIL, continues to provide a flat rheology along with reduced gel strengths and low plastic viscosities and yield point. The system delivers excellent Rates of Penetration (ROP), allowing maximum hole cleaning and reduced ECD. The system was run with an Oil-to-Water Ratio (OWR) of 75:25 instead of the traditional 80:20, reducing the use of diesel base oil while maintaining an excellent rheological profile.


  • The initial ROP averaged between 250– 300 ft/hr (76– 91 m/hr), with a 14-day average of 640 ft/day (195 m/day) while drilling the intermediate hole section.
  • Minimal amounts of lost mud through the Oil-Base Mud (OBM) interval, including the Mission Canyon formation, have helped reduce overall drilling fluid costs. The contributing attributes of a flat, stable rheology allows effective ECD management and pressure control.
  • The directional curve was built to 90 degrees for the lateral work in the Bakken formation; 7-in. casing was run and cemented through the curve with full returns throughout the job.
  • Drilling days on every rig have been reduced from an average of 9.1 days in the OBM interval to 7.6 days.
  • Overall, yearly OBM interval costs have decreased from $6.43 to $5.82/ft, based on a 53-well comparison with the MEGADRIL system being used on the majority of wells in 2008.
  • The 75:25 OWR decreased average per-well use of diesel by 240 bbl (38 m3) for tangible cost savings per well of approximately $15,000 compared to typical invert formulation with an 80:20 OWR.
  • Average total well days have also fallen from 20.23 days to 14.91, an improvement of 5.3 days.

Download: MEGADRIL System Saves 1.5 Drilling Days and $15,000 Average Per Well in North Dakota (0.50 MB PDF)

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