EM Seabed Logging on the Troll Field

A seabed logging R&D study was conducted on the Troll Field in December 2003 – January 2004. Different EM waveforms and frequencies were tested to optimize the hydrocarbon response from this shallow water gas and oil field. The survey consists of 41 receivers, deployed along a line crossing the Oil Province, the Western Gas Province and the Eastern Gas Province of the Troll Field. All receivers recorded two orthogonal components of the horizontal electric field, and 12 receivers measured in addition two orthogonal components of the horizontal magnetic field. The R&D study was carried out as an attempt to qualify seabed logging for shallow waters (less than 500 m) and optimize acquisition parameters for such cases. Up until now the marine controlled source EM method has been qualified for use in deep waters (more than 1000 m water depth) mainly because of the disturbing influence from the air wave in shallower water areas. The Troll Field seabed logging data is of excellent quality and helps in solving problems related to shallow water applications of this method.