How Can MEMS Gyro Tools Directional Module Achieve Near-Bit Installation?

Challenge: Traditional magnetometer-based MWD tools have inherent limitations: they rely on the Earth's magnetic field and must be installed in expensive non-magnetic drill collars to isolate the magnetic interference from the steel drill string, resulting in measurement points being far from the drill bit and limiting real-time performance and accuracy.

Solution: The ER-Gyro-19 MEMS gyro tool directional module uses the Earth's rotation axis as a reference for north finding and can be integrated into shorter, more conventional tool subs and installed closer to the drill bit.

Results: This not only solves the problem of operational limitations due to magnetic field interference but also significantly improves the real-time performance and accuracy of wellbore trajectory control by enabling near-bit azimuth measurement, reducing trajectory prediction uncertainty.

In directional drilling, the installation sequence of the downhole tool string is not arbitrary; it must follow the logic of "build-up" → "measurement" → "transmission." The mud motor and elbow are responsible for changing the drill bit's direction, while the MWD/LWD measurement tool precisely measures the changes in the wellbore trajectory resulting from the action of the build-up tool, including key parameters such as inclination and azimuth. It must be positioned after the build-up tool to measure the drilled wellbore trajectory.

The "Distance Shackles" of Fluxgates

The MWD tool is connected to the bottom-of-the-hole assembly (BHA) and typically consists of a triaxial magnetometer and a triaxial accelerometer. It must be installed in a dedicated non-magnetic drill collar to isolate it from the magnetization effects of the surrounding environment.

However, due to the limitations of the non-magnetic drill collar's structure and installation location, it is generally placed 60 feet (18.3 meters) or more away from the drill bit, resulting in a certain measurement lag.

The "Position Freedom" of the MEMS Gyro Tools Directional Module

The ER-Gyro-19, designed specifically to replace fluxgate magnetometers, features a high-precision triaxial MEMS gyroscope and triaxial accelerometer. It boasts self-north-finding capability, maintaining tracking accuracy in azimuth (0.5°), inclination (0.1°), and tool face (1 secL) even under strong vibration. Its characteristics and technology perfectly meet the requirements of near-bit, non-magnetic MWD/LWD measurements.

Measuring only 136.8 x 20.3 x 19 mm, it allows for direct in-situ replacement of traditional fluxgate magnetometer sensors with the same electrical interface and mechanical structure, without requiring modifications to existing probe structures.

It eliminates the need for long non-magnetic drill collars, allowing it to be encapsulated within a smaller non-magnetic protective sleeve compared to conventional steel drill collars. It can be positioned as far forward as possible in the bottom drill assembly (BHA) for near-bit measurements.

Key Advantages of Near-Bit Non-Magnetic Measurement:

Significantly Improved Measurement Accuracy: The ER-Gyro-19, positioned closer to the drill bit, captures real-time changes in the wellbore trajectory, effectively eliminating measurement errors caused by distance in traditional measurements.

Expanded Drilling Operation Boundaries: The ER-Gyro-19 maintains stable measurement performance even in complex downhole magnetized environments, adapting to various complex drilling scenarios and expanding its application range.

Improved Construction Efficiency and Economy: Eliminating the need for expensive non-magnetic drill collars reduces the procurement and use costs of drilling tools. Simultaneously, it leads to increased drilling success rates, reduced operational risks, and increased recovery rates due to superior wellbore trajectories, resulting in significant economic benefits for oil and gas field development.