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Gyro wellbore survey meter

Jan 15, 2019

It is a general term for the inclinometer which USES gyro elements to determine the inclination Angle of borehole.The most classic is the inclinometer with mechanical frame gyroscope, which has been used almost all in the past few decades.The bearing measured by this gyroscopic inclinometer is relative.Before the instrument can be lowered into the borehole, it needs to be aligned in one direction on the ground, and then the mechanical gyro, which is mounted on a three-degree-of-freedom gimbal frame, is started to achieve a stable high-speed rotation state.

The top is now oriented.Under ideal conditions, the rotation of the instrument and the deflection of the inclined direction of the borehole cannot change the initial direction of the gyro rotor. The inclination of the borehole can be calculated by measuring and recording the rotation Angle of the instrument relative to the initial direction.Obviously, the inclination of the hole is calculated from the initial direction of the top, and the measurement is called the relative bearing.In the late 1990s, silicon micromechanical gyro components appeared, which were actually angular velocity sensitive components rather than the high-speed rotors that traditional mechanical gyros maintain orientation.By integrating the angular velocity signal on the inclinometer, the Angle relative to the initial direction of the instrument as it moves through the borehole can be theoretically calculated.Furthermore, the inclination Angle change of the borehole relative to the initial direction can be calculated.However, due to the influence of sensitivity, noise, drift and other factors, practical level cannot be achieved at present.Fiber optic gyroscope (fog) and dynamically tuned gyroscope (DDG) with higher sensitivity and precision for diagonal velocity measurement have been successfully applied to inclinometer in recent years.

Although these components are also called gyroscopes, they are angular velocity sensitive components, as are silicon micromechanical gyroscopes.Unlike silicon micromechanical gyroscopes, they are orders of magnitude more sensitive to angular velocity.Using their high sensitivity to angular velocity, we can directly measure the angular velocity vector of the earth rotation, and then determine the inclined orientation of the borehole.This direction is relative to the North Pole of the earth.This gyroscope is called the self-seeking north gyroscope, which is the best horizontal and most widely used inclinometer at present.