Case Study: Ecopetrol Saves USD 472,651 and Overcomes Hole Instability in Chichimene Field, Colombia

Integrated casing-while-drilling operation achieves 72-ft/h on-bottom ROP

Challenge: Improve drilling performance in 12 1/4-in hole section despite hole instability issues caused by depletion; set 9 5/8-in casing shoe in formation base.


  • Stabilize the wellbore using TDDirect CD casing-while-drilling service.
  • Drill the 12 1/4-in interval using a PDC bit from Smith Bits, PowerDrive X6 675 RSS, and OnGauge torque-reduction sealed sealed bearing roller reamer.
  • Customize the bit in IDEAS integrated drillbit design platform.
  • Use water-base mud (WBM) drilling fluids from M-I-SWACO.


  • Saved USD 472,651 drilling hole section to TD and setting the casing shoe on target.
  • Achieved a maximum on-bottom ROP of 72 ft/h [22 m/h]; instantaneous ROP reached a maximum of 300 ft/h [91 m/h] in the top portion of the section.

Increase ROP in highly depleted formation with hole instability issues

As part of an ongoing drilling campaign in the Chichimene field in Colombia, Ecopetrol planned to drill a well and needed to overcome hole instability issues caused by depletion in this brownfield. As experienced in offset wells, the field presents high risk for stuck pipe and lost-in-hole events. Typically, these offset wells were drilled using conventional BHAs, which required high flow rates to effectively clean the hole. It had also become standard practice to perform a wiper trip in every section. Wiper trips in the openhole section increase risk for stuck pipe incidents.

Ecopetrol wanted to avoid costly issues and increase ROP in the 12 1/4-in hole section of its directional well while reducing wiper trips and eliminating conventional casing running issues and stuck pipe events. Additionally, it was critical that the casing shoe be set at a specific depth to isolate the limestone formation for this 6,462-ft hole section.

Use casing-while-drilling service to stabilize hole and improve performance

Following a multisegment effort that included collaboration with Ecopetrol, Schlumberger recommended TDDirect CD casing-while-drilling service as part of an integrated solution to stabilize the hole and improve performance. Using the TDDirect CD service would help

  • distribute weight on bit (WOB) more evenly by breaking static friction with consistent casing rotation
  • improve borehole cleaning with rotation and high annular velocity
  • maximize borehole strength and stability from plastering effect.

To work in conjunction with TDDirect CD service, a retrievable BHA with an 8 1/2-in PDC bit to drill the pilot hole, PowerDrive X6 675 RSS for directional control, and an 8 3/8-in OnGauge torque-reduction sealedbearing roller reamer in conjunction with a 12 1/4-in underreamer to open the hole to 12 1/4-in was designed by Schlumberger. Using available data, Smith Bits engineers customized the bit in the IDEAS integrated drillbit design platform.

The TeleScope high-speed telemetry-while-drilling service acquired annular pressure data during drilling, which allowed Ecopetrol to better understand the hydraulic behavior of the well and to maintain appropriate dynamic conditions. M-I SWACO provided a WBM that optimized the mud-weight curve. As a result, Ecopetrol was able to drill ahead using a drilling fluid with 1 ppg less density than was required with conventional drilling applications while maintaining good hole cleaning and hole stability.

Saved USD 472,651 and achieved 72-ft/h average on-bottom ROP

This operation marked the first time that it used the OnGauge reamer, which was found to be in good condition after the lengthy interval. Using the integrated casing-while-drilling solution, Ecopetrol achieved an average on-bottom ROP of 72 ft/h overall and up to 300 ft/h in the top section, saving 1.9 days and USD 472,651. Drilling in the Guayabo formation required a flowrate of approximately 700 galUS/min. This enabled Ecopetrol to achieve a higher annular velocity than in conventional drilling applications because the casing string features larger dimensions compared with conventional drillpipe.

The 12 1/4-in hole section was successfully drilled from 1,083-ft [330-m] MD to TD at 7,545‑ft [2,300‑m] MD. Lost circulation was experienced at 3,093-ft [943-m] MD with losses continuing for the next 1,600 ft [488 m]. However, the plastering effect of TDDirect CD service cured the losses and circulation was regained. The 6,462-ft MD section set a record for the longest hole section ever drilled with TDDirect CD service in Colombia. Schlumberger also documented several areas for improvement in future wells. As a result of this success, Ecopetrol plans to use this integrated solution in its next well.

Download: Ecopetrol Saves USD 472,651 and Overcomes Hole Instability in Chichimene Field, Colombia (0.28 MB PDF)

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