An operator in northern Kazakhstan planned to drill four well sections shoe to shoe and acquire formation evaluation data. The operator wanted to drill the 16-in, 12¼-in, 8½-in, and 5⅞-in sections to MD, which totaled more than 20,500 ft [6,250 m], in a single run. Because of the inclination of up to 88° in the 8½-in build section and 5⅞-in drain section, wireline logging was not a viable option, and MLWD would require complex BHAs.
Each section of the well was drilled with a PowerDrive RSS or PowerPak steerable motor, and the real-time and recorded LWD data needed for full formation evaluation was acquired in all sections. In the 12¼-in hole section, real-time gamma ray measurements helped reduce drilling risks by successfully identifying the essential 9⅝-in casing point. SLB provided 16-in and 12¼-in bits optimized for high ROP and designed an 8½-in PDC bit that could be steered with a PowerPak motor for the build section.
The BHA for the nonstandard 5⅞-in hole size included an MDi516 PDC bit, 4.75-in OD PowerDrive X6 RSS, an ImPulse integrated MWD platform, SonicScope™ multipole sonic-while-drilling tool, and an adnVISION475™ azimuthal density neutron tool.
Each well section was drilled shoe to shoe—with one BHA for each section—without tool failures, even though the circulation time for the 12¼-in and 5⅞-in sections exceeded 250 hours. The well was drilled 12 days earlier than planned with zero NPT.
