Maintain positive directional response in conglomerate formation

One of the main challenges in drilling 8 3/4-in curve sections below 12,000 ft in the Granite Wash play in the Anadarko basin is the complex geology and combination of washed formations with a wide variety of compressive strengths. Drilling operations in the Granite Wash vary from high-ROP runs with minimal bit damage to more complicated jobs where multiple bit runs are required to finish curve sections approaching conglomeratic, hard, and abrasive formations.

Historically, many operators have chosen roller cone bits over PDC bits to drill curve sections in the Granite Wash because they give improved directional control, consistent build rates, and less reactive torque with durable cutting structures.

Enervest sought to drill an entire curve section in one run with the desired build rates (11°/100 ft) at a similar, or faster, ROP than was achieved in previous runs in the same play with a PDC fixed cutter and roller cone combination hybrid bit. The operator wanted to minimize risk involved with moving bit parts, including possible bearing failure and loss of cone, without putting limitations on drilling hours.

Implement optimal cutting structures for directional drilling application

Following extensive analysis and consultation with Enervest’s drilling superintendent, Schlumberger recommended the StingBlade bit to drill the curve section and land in the Granite Wash B formation target. Using the IDEAS integrated drill bit design platform, the engineering team modeled directional-friendly cutting structures with strategically placed Stinger elements across the StingBlade bit face by analyzing drilling assembly dynamics through formations of varied compressive strengths. The StingBlade bit reduces reactive torque to provide the directional driller with better toolface control for optimal bit performance.

Increased ROP and higher build rates with less WOB

The StingBlade bit drilled the Armstrong 2004 HB Well’s planned curve section in one run with excellent toolface control. The operation exceeded the desired high build rates, from 13°/100 ft to 15°/100 ft, and increased total rotation hours where higher penetration rates were achieved. With the StingBlade bit, the on-bottom instantaneous median penetration rates were 23% faster in rotation mode, with less WOB, compared to two combined hybrid bit runs. According to real-time data, the median true sliding ROP was more than twice that of the hybrid bit runs.