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Points to Ponder
Minimum Curvature assumes a simple curve between stations. So long survey intervals may not be accurately modelled if large toolface changes or slide/rotate transitions have happened in the interval. By examining the lengths over which sliding took place, it is possible to estimate the yield, but it is only an estimate.
h s of n n obj c on o us ng ‘syn h c’ su ys n su y po , but these are no more synthetic than a projection to bit.
9. Gyo u yng
9.1 Background and History of Gyros
What is a Gyro? A Gyroscope is a device which enables us to measure or maintain an orientation in free space and rotor gyros specifically, operate on the principle of the conservation of angular momentum. The first gyros were built early in the 19th century as spinning spheres or disks (rotors), with designs incorporating one, two or three gimbals, providing the rotor spin axis with up to three degrees of freedom. These early systems were predominantly used within the academic community, to study gyroscopic effects as rotor speeds (angular momentum) could not be sustained for long periods, due to bearing friction effects. The development of the electric motor overcame this rotation decay problem and lead to the first designs of prototype gyrocompasses during h 1860’s.
Figure 48: Representation of a basic gyrocompass.
As with most scientific and technology advances, continued development and refinement was propagated and accelerated to address military applications and by the ly 1900’s gy os w b ng us d n m ny ud con ol, o n on nd n g on applications. Rotor gyros are still by far the most common system used by the oil industry. During the second half of the 20th century several additional technologies were developed and exploited providing gyroscopic capabilities. These included: • Vibrating Gyros • Hemispherical Resonator Gyros • Quartz Rate Sensors • MHD Sensor • Fibre Optic Gyros • Laser Gyros • MEMS Gyros The systems currently considered to have the most potential for the oil industry are the Laser and MEMS systems. Indeed, Inteq developed and successfully marketed and operated the highly accurate RIGS (Ring-Laser Inertial Gyro Surveyor) for many years servicing the North Sea. The current performance capability of the MEMS unit is still less than desired but is regarded as having potential for the future.
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