Case Study: Spear PDC Bit Technology Increases ROP 37% Drilling Shale Gas Well in Latin America

Steel-body PDC sets back-to-back ROP records drilling in Argentina’s Patagonia region

Challenge: Drill 8 1/2-in curve and lateral sections in shale gas well with a single bit while maintaining good directional control in curve and high ROP.

Solution: Run innovative Spear steel-body shale-optimized PDC drill bit on a steerable motor BHA and rotary steerable BHA.

Result: Drilled the first 8 1/2-in shale gas well with one bit on two different BHAs; increased ROP on the first well by 13% drilling the curve (6.74 m/h) compared with the three-well offset average (5.98 m/h); increased ROP in the curve on the next well by 37% setting back-to-back field ROP records; progressively increased ROP in lateral hole section.

Exporting USA shale drilling technologies

The impact of horizontal drilling and hydraulic fracturing techniques in the USA shale plays has been profound. Combined, these procedures have yielded significant new production from unconventional natural gas reservoirs in North America. Conservative estimates place Latin America’s shale gas reserves at 2,100 Tcf and several significant test projects are underway in Argentina and Mexico.

PDC bit with superior directional control and high ROP potential required

An operator is using horizontal drilling techniques to develop tight sand gas reserves in Argentina’s Patagonia region. Historically, the curve has been drilled with an 8 1/2-in bit, the lateral with a 6 1/8-in tool. This type well required a trip for bit changeout to gain horizontal access to a tight sand formation. In an attempt to establish commercial gas production from the shale, the operator wanted to test the formation with an 8 1/2-in curve and lateral hole section. Due to hole instability issues, the curve has been drilled with a positive displacement motor and the lateral has been constructed with a point-the bit rotary steerable system (RSS). However, PDC bits designed for the curve have strong build capabilities and predictable directional control but often deliver low ROP in the lateral. Conversely, bits intended for the lateral section are built to produce high ROP but often at the expense of directional control. The technology gap would force the drilling team to choose between steerability or high penetration rate. To address the issue would require a new PDC design that could run efficiently on a positive displacement motor (PDM) and RSS BHA while achieving the required build rates and high ROP in both hole sections.

Operating parameters used on the steerable motor BHA (curve):

  • PDM speed: 0.29 rev/gal
  • Motor bend angle: 1.5°
  • Maximum DLS: 5.669°/30 m
  • Flow rates from 360 to 390 galUS/min
  • Weight on bit between 9,000 to 18,000 lbf
  • Mud weight from 10.4-13.3 lbm/galUS

Operating parameters used on the RSS BHA (lateral):

  • Flow rates from 360 to 400 galUS/min
  • Weight on bit from 22,000 to 27,000 lbf
  • Mud weight 14.2 lbm/galUS

Engineering analysis

Using offset data that included operator-provided BHA details, directional profiles, and mud properties, an application analysis was performed using the following proprietary modeling and database tools:

  • IDEAS drillbit design system with vibration analysis capabilities
  • DBOS drillbit optimization system/rock strength analysis
  • DRS drilling records library.

Spear PDC bit solution

Based on knowledge gains from the study and field experience from drilling shale formations in the USA unconventional gas plays (Haynesville, Eagle Ford, and Marcellus), Smith Bits developed the 8 1/2-in Spear SDi513MHPX specifically for the Argentina shale gas application with the following technology platform:

  • Optimized hydraulics keep the cutter’s edge on formation, maximizing ROP.
  • Bullet-shaped body directs cuttings around the bit and into the junk slots.
  • Reduced body diameter increases the distance between the bit and borehole wall, allowing the bit to pass over or through a cuttings bed without blade packing or nozzle plugging.
  • Steel construction enables the bit’s blade height to be increased and its width decreased, enabling the junk slot area to be maximized.

The unique combination of technologies would enable the bit to efficiently deliver the required build rate, directional control, and fast ROP in the curve and lateral sections.

Successful application of USA shale bit in Latin America

The 8 1/2-in Spear SDi513 PDC bit was run on a steerable PDM BHA and drilled 1,162 m of curve section through the carbonate formation in just 172.5 hours, setting a new ROP record of 6.74 m/h. Using the Spear drill bit enabled the operator to drill 13% faster compared with the three-well offset average of just 5.98 m/h. The same bit was then run on a RSS BHA and drilled 999 m of lateral borehole in 105.5 hours at a high ROP of 9.47 m/h. This was the first time the operator was able to drill the curve and lateral sections in an 8 1/2-in hole size with one bit. After the initial success, the 8 1/2-in SDi513 was used on two subsequent wells with increasingly better results. The bit consistently drilled out from under the intermediate casing then completed the curve and lateral sections with one bit on a BHA that included a motor and RSS. While drilling Well B, the bit set a second ROP record in the curve on a steerable motor when average ROP reached 8.94 m/h, an improvement of 37% compared with the first record of 6.74 m/h set on Well A. Also, average ROP in the lateral section on the last two wells improved by 19%, with the final well reaching 12.39 m/h. The bit was pulled in good dull condition in all three cases.

Strategy going forward

The long-term goal is to complete the curve and lateral in one run with the Spear bit and the PowerDrive Archer high build rate RSS to eliminate the trip to change out the downhole drive device. When the one-run objective is achieved, additional tool combinations and variations in operating procedures and parameters will be implemented to further reduce drilling costs and enhance production potential.

Download: Spear PDC Bit Technology Increases ROP 37% Drilling Shale Gas Well in Latin America (0.68 MB PDF)

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Spear PDC bit set sback-to-back ROP records drilling the curve through carbonate on a PDM.Spear PDC bit consistently improved ROP drilling the lateral through shale reservoir on an RSS.
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