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oa Marine CSEM for Gas Hydrate Exploration Using a Seafloor-towed Multi-receiver System
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, 76th EAGE Conference and Exhibition - Workshops, Jun 2014, cp-401-00067
- ISBN: 978-90-73834-90-3
Abstract
In the past years BGR – the German Federal Institute for Geosciences and Natural Resources has been developing unique marine CSEM systems to explore the electrical attributes of the shallow seafloor. CSEM data are sensitive to the presence of resistive gas and gas hydrate in the sediment, and provide complementary volume information which, if used in connection with seismic and other exploration methods, e.g. drilling, allow for a better evaluation of the gas or gas hydrate resource potential. The gas hydrate setting differs from the exploration of conventional offshore oil and gas reservoirs as typical gas hydrate deposits are smaller in scale und at shallower depths below the seafloor. Therefore instrumentation and survey configurations need to be adapted. HYDRA, the seafloor-towed, multi-receiver system has been recently refined with a new signal generator and receiver units which both allow for online communication and data transfer. 1D and 2D inversions of CSEM data collected offshore New Zealand result in highly anomalous resistivities over several methane seep sites within the gas hydrate stability field which are believed to be caused by concentrated gas hydrates below the seeps.