The Magnetic Single Shot survey (MSS) is an accurate field-proven instrument measuring inclination and magnetic azimuth, which consists of an electronic timer, camera and combined compass / inclinometer. The instrument is run in the same way as the TOTCO.
When the timer fires, a film disc is exposed to the angle unit, thus recording the survey.
For vertical wells and possibly shallow directional wells, the tandem stack magnetic single shot (run with two instruments) should be used if MWD tools are not run.
The Magnetic Single Shot survey should be taken to monitor the borehole course at depth increments of no more than 500 ft.
Quality Control for Magentic Survey
- every precaution must be taken to achieve the best possible accuracy
- two Magnetic Single Shot survey instruments must be available on each rig for drilling operations
- each Magnetic Single Shot survey kit should be re-calibrated every six months (and the dates recorded)
- the disks of pictures taken should be stored with the wellfile.
