An operator in the Eagle Ford Shale of Texas designed a well where the curve and lateral intervals would be drilling through limestone and shale formations with unconfined compressive strengths between 6,000 psi [41.4 MPa] and 15,000 psi [103.4 MPa]. The curve consisted of limestone and shale interbeds, which can cause issues with toolface control when sliding through the transitions.
The operator sought to drill the interval using a single BHA with high differential pressure motors, ranging from 500 to 1,200 psi [3.4 to 8.3 MPa] of differential pressure. The ideal drill bit would deliver high penetration rates and enhanced toolface control while withstanding high differential pressure.
SLB suggested the AxeBlade ridged diamond element bit to achieve the desired performance. The ridged diamond element combines the shearing action of a conventional PDC cutter with the crushing action of a tungsten carbide insert (TCI) to cut rock more efficiently. The cutters’ unique geometry delivers higher instantaneous ROP, reduces overall torque, creates less reactive torque fluctuation, and improves toolface control.
The IDEAS™ integrated dynamic design and analysis platform was used to simulate the directional response of a formation transition in the curve section. The AxeBlade bit showed less overall torque and held toolface angle through the shale and carbonate transition better than the offset bit.
Using the AxeBlade bit, the operator drilled 3,586 ft in 35 hours for an ROP of 102.5 ft/h—an improvement of 29% compared with the performance achieved in two offset wells on the same pad. Additionally, the bit successfully landed the well with enhanced toolface control and resulted in a better dull condition compared with the offset runs.
