Gyro Multi-Shots (GMS) shall only be run in preference to EMMS to verify the surveys used to drill a hole section where magnetic interference may not be corrected. Gyro Multi-Shots are also used for ‘tying-in’ MWD surveys.
They are also used inside a driven conductor (where a Gyro Multi-Shots is required for tying-in shoe co-ordinates to the surface).
Gyro Multi-Shots surveys may be taken inside casing eg., 20in and 13.3/8in casing or occasionally in drill pipe or tubing.
The Gyro Multi-Shots survey is not required for non-critical open hole sections which are to be plugged back.
The depth increment between stations shall not exceed 100 ft.