Case Study: Halcón Resources Drills
20,645-ft Horizontal Well at Record Speed in Bakken Shale

Managed-pressure and underbalanced drilling enable reaching TD by mitigating influx and contamination, North Dakota

Challenge: Drill a 20,645-ft [6,293-m] horizontal well to TD while mitigating influx and contamination issues.


  • Use @balance managed pressure and underbalanced drilling services to assess downhole drilling conditions and risks.
  • Design an optimized drilling solution using VIRTUAL HYDRAULICS software from M-I SWACO, a Schlumberger company.


  • Drilled the 20,645-ft well to TD with decreased NPT.
  • Maintained condition of the drilling fluid through drilling and tripping.
  • Achieved an operator record for fastest lateral drilled in the Bakken Shale.

Manage pressure while drilling

When drilling a 20,645-ft horizontal well in McKenzie County, North Dakota, Halcón Resources experienced influx issues and contamination of the brine drilling fluid. The operator considered using a heavier-density—and more expensive—drilling fluid, but doing so would increase the likelihood of heavy losses. Thus, Halcón sought a viable, efficient solution to successfully reach TD.

Use @balance services to mitigate risks

M-I SWACO recommended using @balance services to assess every aspect of the drilling project, including expected conditions and risks. @balance services combines advanced managed-pressure and underbalanced drilling technologies and services with evaluation to help identify and prevent risks that are associated with unstable boreholes, uncertain pressure regimes, equivalent circulating densities (ECD), and narrow pressure windows.

After performing well engineering analysis using @balance services and VIRTUAL HYDRAULICS software, M-I SWACO suggested using 10-ppg drilling fluid, which would allow for the continuous use of sodium chloride brine while minimizing and controlling influxes at all stages of the operation. When drilling began, no influxes were experienced. Backpressure was held at 350 psi during connections, maintaining near-constant bottomhole pressure to help reduce the probability of fatigue cycling of the wellbore.

While attempting to hold backpressure, the bottomhole pressure began to gradually reduce, and flow returns were observed, causing both floats on the drillstring to fail. At only 100 ft from TD, the float failures prevented the necessary backpressure to be applied to the well.

To overcome the float failures, the well engineering team used VIRTUAL HYDRAULICS software to determine a weighted pill that would offset the applied 700-psi backpressure and help reach TD. The pill remained in the string to offset the backpressure required to offset swab.

During the tripout, the applied backpressure mitigated the swab, and no influxes were recorded. The bit was pulled out to the shoe before running back to TD to ensure a gauged open hole prior to running casing. When tripping out the second time, the team spotted a 90-bbl, 13-ppg pill at 10,600-ft [3,231-m] MD. The method from the first trip was applied by slugging the pipe with 10 bbl of 14-ppg mud while holding an applied backpressure of 600 psi.

Achieved drilling objective, set record for Halcón

Using integrated M-I SWACO services, Halcón successfully drilled the 20,645-ft well to TD, and met its drilling objectives. For both trips out, the drillpipe was pulled dry, the hole was clean of oil and gas, and the drilling fluid was in excellent condition. This operation set a record for Halcón Resources for the fastest lateral well drilled in the Bakken Shale.

Download: Halcón Resources Drills 20,645-ft Horizontal Well at Record Speed in Bakken Shale (0.12 MB PDF)

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