Page 12: of Offshore Engineer Magazine (Jan/Feb 2026)

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Inertial sensors, the heart of downhole The emergence of MEMS inertial sensors navigation for demanding applications

Analog quartz accelerometers have been considered as Micro-Electro-Mechanical Systems (MEMS) emerged in the gold standard for measuring inclination, as they are the 1980’s as a cost-effective approach to overcome the tech- known to be very accurate with excellent thermal behavior. nical limitations and high cost of conventional inertial sens-

However, these bulky devices tend to be fragile and may ing technologies. MEMS manufacturing leverages large-scale cause feld failures that negatively impact the equipment production techniques inherited from the microelectronics uptime and drastically increase the costs of maintenance. industry, which drastically contributes to reducing their unit

In addition, their integration into modern digital-cen- price. MEMS are known to demonstrate higher reliability, tric MWD tools can be a challenge in terms of electronics especially when it comes to shocks resistance, and their min- complexity, with a need to manage data acquisition and iature size and power consumption allow them to get em- analog-to-digital conversion at system-level. Finally, their bedded in reduced spaces and battery-operated systems.

high price point limits their usage to premium solutions. In the past decades, MEMS inertial sensors witnessed a

Azimuth can be measured with a magnetometer, or with tremendous growth in both consumer and industrial mar- a gyroscope using a technique called gyro-compassing. Mag- kets. Their performance improved year after year, minimiz- netometers act as a compass to determine the heading of a ing drifts and improving their stability, to eventually fnd system with respect to the magnetic north. They are current- their way into high-performance Inertial Measurement Units ly widely used in directional modules, but their high sensitiv- (IMU) used for positioning, navigation, and heading systems ity to metallic environments can degrade their performance in demanding aerial, terrestrial and maritime applications.

when used in mineral-rich or magnetically disturbed soils.

Gyro-compassing can be used for azimuth determination

Directional drilling with MEMS with a gyroscope that is accurate enough to sense the rota- In the energy market, MEMS accelerometers have been tion of the Earth (only 4 millidegrees per second) and deter- envisioned as a miniature and cheaper alternative to legacy mine the heading of the drilling tool with respect to North. technologies such as quartz sensors. Providers of drilling

This technique, known as Gyro-While-Drilling (GWD) is equipment started to evaluate MEMS sensors initially implemented with mechanical gyros (spinning wheels archi- qualifed for the automotive market, but their performance tecture) which are insensitive to magnetic environments, at was too limited to be used extensively in energy applica- the expense of a high price, high sensitivity to shocks and tions requiring extreme operating temperatures. The re- high failure rate due to their internal moving parts. cent emergence of new MEMS sensors qualifed for 150°C 12 OFFSHORE ENGINEER OEDIGITAL.COM