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Case Study: Spear Bit Sets ROP Record Drilling for Shale Gas in Argentina

PDC delivers 31% greater ROP in first, one-run drilling of entire 8 1/2-in well section

Challenge: Drill 8 1/2-in section of a shale gas well with a single bit while maintaining good directional control and high ROP in the section’s curve.

Solution: Run innovative, application-specific Spear shale-optimized steel-body PDC drill bit.

Result: Drilled an 8 1/2-in section of a shale gas well with a single bit for the first time in the field’s history with a 31% faster ROP through the well’s curve section to set a field record.

Single bit suitable for both curve and lateral sections of shale gas well required

An operator planning to drill shale oil and shale gas exploratory wells in the Neuquen basin required an 8 1/2-in PDC bit that would drill curve and lateral sections at maximum penetration rates while providing good directional control. Traditionally, bits designed for the curve section have strong build tendencies and predictable toolface control, but often deliver low ROP in the lateral. Conversely, bits that target the lateral section are built for aggressive, fast ROP with less directional control. A PDC bit was needed that could be run on a positive displacement motor (PDM) with a lower bend angle, enabling rotation and a high ROP in the lateral. At the same time, the bit had to be capable of producing the required rates.

Application-specific shale-optimized steel-body PDC bit selected

Using knowledge and experience gained from US shale plays, Smith Bits designed the Spear PDC bit specifically for shale drilling. BHA data, directional profile, mud properties, offset run information, and other application factors were analyzed using several proprietary modeling and database tools:

  • IDEAS integrated drillbit design platform
  • DBOS drillbit optimization system for rock strength analysis
  • DRS drilling record system, a collection of nearly 3 million bit runs.

Based on their analysis, bit design engineers selected a 8 1/2-in SDi513MHPX Spear PDC bit, which provides a good balance between high-build rates, superior directional control, and fast ROP in the well’s curve and lateral sections.

Record ROP in curve and entire 8 1/2-in section successfully drilled

The Spear bit on a steerable PDM drilled 1,162 m of curve section in 172.5 h, setting an ROP record of 6.74 m/h in this application. Compared with an offset well, this ROP represented an improvement of 31%. The same bit on a rotary steerable system (RSS) drilled 999 m of lateral section in 105.5 h. Both efforts satisfied drilling performance objectives and saved bit costs and rig time.

The 8 1/2-in Spear bit was run on a steerable PDM in the curve section, with the following operating parameters:

  • PDM speed: 0.29 rev/galUS
  • Motor bend angle: 1.5°
  • Maximum dogleg severity (DLS): 5.669°/30 m
  • Flow rate: 360 to 390 galUS/min
  • Weight on bit (WOB): 8,000 to 16,000 lbf
  • Mud weight: 10.4 to 13.3 lbm/galUS

For the lateral section, the bit was run on RSS with the following operating parameters:

  • Flow rate: 360 to 400 galUS/min
  • WOB: 20,000 to 24,000 lbf
  • Mud weight: 14.2 lbm/galUS

Download: Spear Bit Sets ROP Record Drilling for Shale Gas in Argentina (0.65 MB PDF)

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Record ROP of 6.74 m/h
Set in Neuquen Basin

Offset well bit performance in 8 1/2-in curve section, Neuquen basin.
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