Schlumberger

Case Study: Customized BHA Saves 12 Rig Days in Northern Kazakhstan

Rotary steerable systems, steerable motors, optimized drill bits, and MLWD services drill shoe to shoe in one run with no NPT

Challenge: Drill four well sections shoe to shoe in one run and acquire MLWD data for formation evaluation.

Solution: Integrate PowerDrive rotary steerable systems (RSSs) and PowerPak steerable motors with compatible drill bits, and quadcombo LWD and real-time MWD services.

Result: Drilled each section shoe to shoe in one run 12 days ahead of plan, with zero NPT. Acquired real-time and recorded MLWD data for full formation evaluation.

Drill shoe to shoe in four sections

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, 12 1/4-in, 8 1/2-in, and 5 7⁄8-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 8 1/2-in build section and 57⁄8-in drain section, wireline logging was not a viable option, and MLWD would require complex BHAs.

Develop integrated BHA for Kazakhstan wells

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 12 1/4-in hole section, real-time gamma ray measurements helped reduce drilling risks by successfully identifying the essential 9 5⁄8-in casing point. Smith Bits, a Schlumberger company, provided 16-in and 12 1/4-in bits optimized for high ROP and designed an 8 1/2-in PDC bit that could be steered with a PowerPak motor for the build section.

The BHA for the nonstandard 5 7⁄8-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.

Save 12 days of drilling time

Each well section was drilled shoe to shoe—with one BHA for each section—without tool failures, even though the circulation time for the 12 1/4-in and 5 7⁄8-in sections exceeded 250 hours. The well was drilled 12 days earlier than planned with zero NPT.


Download: Customized BHA Saves 12 Rig Days in Northern Kazakhstan (0.45 MB PDF)

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Customized BHAs Drill Four Well Sections TD in One Run

The total measured depth for the four sections was more than 6,300 m.Each well section was drilled shoe to shoe with one BHA for each section.
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