Mature Fields

Specific Challenge

Reduce uncertainty and optimize well placement by GWD, MWD, and LWD


North Slope of Alaska



An operator on the North Slope of Alaska needed to drill a well through 900 ft of magnetic interference from offset wells. The main objectives were: 1) conduct high-accuracy surveys to optimize well placement, and 2) reduce the ellipse of uncertainty in drilling an extended tangent almost due west, at approximately 273° azimuth. Previously, gyro single-shots on e-line or spinning-mass GWD systems were used for such projects. However, due to current market conditions and a desire to reduce rig time/cost, a faster method was required to collect survey data and ensure precise directional drilling to avoid wellbore collisions, thus, minimizing nonproductive time (NPT). 

The GyroStar™ gyro-while-drilling (GWD) service from Halliburton Sperry Drilling was the recommended alternative to safely drill the entire 12¼-in. surface hole section from 0 to 6,973-ft MD, unaffected by magnetic interference. The compact design allowed SPEAR™ solid-state sensors to be placed closer to the bit in the measurement-while-drilling (MWD) string for definitive survey results. After seven days on standby, drilling the section, and completing an outrun memory multi-shot, the system had only used 38% of its battery life (compared to a conventional GWD solution, which would have taken two full batteries). 

Previous solutions were limited by a backreaming out of hole maximum ROP of 60 RPM, but the GyroStar service had no RPM limits thanks to its downlink into memory multi-shot mode prior to tripping out of hole. Other benefits delivered by this new technology included: 

  • Zero NPT and no disruption to bottomhole assembly (BHA) functionality 
  • Survey time reduced by 30%—decreased from 2 min., 30 sec. to 1 min., 45 sec 
  • Reduced well time by six hours versus a wireline gyro system 

This service further helped the operator maximize asset value with reduced tool handling and fewer number of crew members onsite, and operations remotely monitored for quality assurance.


Non-Productive Time (NPT)


Reduction in Survey Time


Hours of Well-Time Saved