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CSEM and 3D Inversion Modelling for Gas Hydrate Exploration presented in Taiwan

Peter Kowalczyk, CTO of OFG presented at the 2015 Workshop on the Recent Development on Technology and Gas Hydrate hosted at Academica Sinica in Taiwan. The workshop was attended by gas hydrate researchers from Taiwan, Korea, Germany and Japan. OFG presented "CSEM for gas hydrate exploration - a new approach using the Scripps Institution of Oceanography CSEM Vulcan system".The presentation focused on the the towed CSEM technology for the detection and modelling of gas hydrates. The role of CSEM in the exploration model for a GH deposit was presented as well as a 3D EM inversion model.

CSEM is an electrical method well suited to mapping resistors, therefore the towed CSEM Vulcan system is suitable for characterizing shallow gas hydrate deposits for several reasons. Some of the key points about the towed CSEM Vulcan system that were raised during the workshop were as follows:

• It is complementary to other geophysical and geological methods and is the only method that has the promise of assessing both the volume and concentration of Gas Hydrate, other than drilling. Thus it fits well into a resource definition programme.

• BSR is an imperfect hydrate indicator. Gas rich zones often blank seismic data. For example, accordng to Majumdar, 2014, in the Gulf of Mexico 42% of BSRs lack hydrate and 15% without BSRs do have hydrate.

• CSEM can be used to rank gas hydrate deposits according to resistivity. CSEM is an electrical method well suited to mapping resistors.

• The CSEM Vulcan equipment and software works well and provides a tested exploration method with low risk. Survey procedures are well understood by OFG.

• Robust 2D and 3D inversion codes are used by OFG to model the resistors..

• The VULCAN CSEM system that OFG deploys has high spatial resolution and can distinguish strong resistors from weak ones.

• And is much cheaper than drilling! Large areas identified as prospective can be tested for priority targets. This improves the efficiency of a drilling campaign, and provides confidence that a drilling programme has tested the best targets.

The complete presentation from the workshop can be downloaded from the link OFG_2015.03.27_Taiwan_Gas_Hydrate_CSEM-R01-mk.pdf


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