Multipurpose tool improves data interpretation and survey accuracy

A new multifunctional survey tool has been launched by Reflex Instrument.

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A new multifunctional survey tool has been launched by Reflex Instrument. A main objective in the development of the Reflex EZ-AQ/EMS was to make it user friendly for oilfield contractors drilling directional wells, says technical manager Kjell Gustafsson.

Results were satisfying when tests were staged in Texas to compare the performance of the tool with that of a gyro, he says. The company now has one tool in use in Ghana and is currently negotiating deliveries to various drilling contractors.

The Reflex EZ-AQ/EMS performs deviation surveys and acts as an inclinometer compass, recording the earth's magnetic field and gravity field in three components. With its small diameter of 25 mm (0.985-in.), it fits into AQ size drill-strings, but can also be used in larger diameter drillstrings.

It has both single-shot and multi-shot electronic capability – it can survey five single shots in a row or 9,000 electronic multi-shots. A five-shot survey can be programmed up to 240 min in advance of shooting by using the built-in LCD display.

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With a length of 9.3 cm and a diameter of 2.5 cm, the Reflex EZ-AQ/EMS multifunctional survey tool is intended mainly for AQ drillstrings.
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The smart part of the tool is a processor based on miniaturized electronics. This calculates the horizontal direction (azimuth) of the borehole relative to magnetic north and its drift or inclination, the roll tool face relative to magnetic north and to gravity, the local gravity field strength and magnetic dip, and also the temperature of the instrument.

The total magnetic field and magnetic dip in the area can be used as a form of quality control, Gustafsson says. If the total magnetic field varies, this may indicate that the borehole is close to another drill casing, or that there is a geological magnetic interference field in the vicinity. It can also help indicate if there is error in the calculations, as azimuth is sensitive to magnetic fields, in which case the survey data will need to be filtered.

Not only is the tool more accurate than conventional tools, but it also provides interpretation of the readings, which conventional tools would require the user to perform. Nor can existing mechanical tools perform both single and multi-shots.

The tool is also robust. It can be used without any shielding in temperatures up to 80° C (175° F) and without a pressure barrel down to 6,000 psi water pressure, equivalent to 4,000 m. For more extreme conditions Reflex has developed a pressure barrel with heat shield that can withstand up to 20,000-psi water pressure (13,800-m water column) and maintain the tool below the critical temperature of 85° C (185° F) for 10 hr at an ambient temperature of 175° C (350° F). The tool can also withstand a shock of 6,000 g, which would put a gyro, for example, out of action.

Reflex's range of survey tools includes Reflex EMS, Reflex EZ-shot, Reflex Maxibore, and Reflex EZ-Dip (inclinometer).

For more information, contact Kjell Gustafsson, Reflex Instrument. Tel: +46 8511 806 10, fax: +46 8511 806 20. kjell.gustafsson@reflex.se, www.reflex.se

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