AnTech Ltd has designed a customised sensor system for an oil service company for use in a well intervention operation being carried out offshore Louisiana, US in the Gulf of Mexico. The deepwater, high-pressure field is situated in over 6000ft of water, and is being developed using a permanently moored semi-submersible production and drilling facility. Known as the Triple Sensor Tool Joint Detection System – or MDET-S, the new system is being used to detect tool joints in risers by measuring changes in magnetic fields that are triggered when a pipe joint passes through the field. The MDET-S is comprised of two primary features: three sets of two sensors, and the control unit. The sensors detect changes in the surrounding magnetic field when a tool joint passes by. The device senses the distortion caused by the additional thickness of the metal joint. The control box receives the signal and responds by indicating that a tool joint has passed by a pair of sensors. The control box also transmits digital and analogue signals to an external data acquisition system that transfers the readings produced to a file located on the technician’s laptop. The technician can then analyse this data and proceed.