Continuous Gyro Tool

Overview

The Continuous Gyro Tool is a wireline-deployed inertial survey logging instrument for oil-gas wells, adopting solid-state gyroscope and MEMS accelerometer inertial measurement technology. Different from traditional multi-shot gyro tools which take discrete spot measurements, it performs uninterrupted high-density sampling while moving up or down the wellbore, continuously calculating wellbore trajectory parameters referenced to true north, free from geomagnetic interference. It is widely used in cased-hole trajectory re-survey, completion operation orientation and wellbore quality evaluation, and can be combined with production logging strings for integrated logging operations.

Working Principle

Inside the tool, high-precision solid-state gyro sensors sense earth-rotation angular velocity, while accelerometers capture gravity vector information. Downhole processing units compute inclination, azimuth and tool-face angle in real-time through inertial navigation algorithms during tool movement. Since it references true north instead of geomagnetic field, it maintains reliable measurement performance inside steel casing, tubing and magnetically abnormal formations, where magnetic-based MWD tools produce large errors. Continuous sampling generates dense depth-matched trajectory points to reconstruct high-resolution 3-D wellbore path.

Key Features

◆ Magnetic immunity: Accurate azimuth measurement within casing/tubing, unaffected by steel pipe and magnetic strata.

◆ Continuous high-density logging: No requirement for stationary station measurement; obtains full-section trajectory in one logging pass, greatly improving operational efficiency compared with multi-shot gyro tools.

◆ Wireline compatibility: Can be run standalone or integrated into production logging tool string, supports real-time surface readout or memory logging mode.

◆ High-resolution wellbore tortuosity detection: Captures tiny wellbore bending and dog-leg variations that discrete surveys may miss SLB.

◆ Harsh downhole adaptability: Rugged mechanical structure for high-temperature and high-pressure cased-hole environments.

Main Petroleum Industry Applications

◆ Cased-hole trajectory re-survey: Re-verify well path for old wells, infill wells and sidetrack wells, correct original MWD survey data with magnetic deviation.

◆ Completion & workover orientation: Provide accurate tool-face azimuth for whipstock setting, perforating, plug-packer deployment and fishing operations.

◆ Wellbore tortuosity evaluation: Detect borehole bending, dog-leg severity, optimize placement of ESP, packers and other downhole completion equipment, reduce equipment wear risk SLB.

◆ Well collision risk assessment: Calculate well spatial position to prevent inter-well collision for dense well pattern development.

◆ Joint interpretation: Cooperates with production logging tools (Holdup, Temperature, Flow, Dual Spectral Noise Tool) to provide accurate depth-azimuth benchmark for production profile and well-integrity logging data.

Typical Tool Specifications

◆ Outer diameter: 43 mm slim-hole design for through-tubing access

◆ Max operating temperature: 175 °C

◆ Max working pressure: 103 MPa

◆ Inclination accuracy: ±0.1°

◆ Azimuth accuracy: ±0.5°

◆ Sampling: Continuous depth-synced high-frequency sampling