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OSEG April 2007 Meeting
	Wednesday 25 April 2007, 18:00 - 21:00
OSEG Meeting WITH "CONTROLLED SOURCE EM" THEME WEDNESDAY APRIL 25th At 18:00 The meeting is most kindly sponsored by WesternGeco. 17:45-18:00 Registration 18:00-18:45 Bruce Hobbs, MTEM Ltd (and EAGE DL): "Inversion of data acquired by the Multi-Transient Electro-Magnetic (MTEM) method" In the MTEM method, a transient current is injected into the earth between two electrodes (the source) and the propagation of the disturbance created is measured as the voltage between a second pair of electrodes (the receiver). The distance between the centre of the source electrodes and the centre of the receiver electrodes is termed the offset. The transient current is typically a coded waveform such as a pseudorandom binary sequence and the measured receiver voltage is deconvolved for the measured source current to obtain the earth?s impulse response. For a given source position, measurements are made over a 40-channel receiver spread yielding impulse response functions for 40 offsets. The source and receiver spread are moved sequentially along a profile over a target of potential interest. A typical MTEM survey acquires a large body of data which needs to be inverted to obtain an earth resistivity model. Impulse responses may be described and sorted using seismic terminology, an example being common mid-point gathers (CMPs). Methods are described for 1D multi-trace impulse response inversion for each CMP gather and these inversions may then be collated to form a 2D cross section. Impulse response functions may also be integrated to form step response functions and these too may be inverted in a number of ways. The methods are compared and illustrated on synthetic and real data sets. Bruce Hobbs is Senior Lecturer at the University of Edinburgh and is co-founder, with Anton Ziolkowski, David Wright and Leon Walker, of the company MTEM Ltd. He is currently on secondment to that company as Director of Research.More information about him and the Distinguished Lecture he gives can be found at http://www.eage.org/index.php?Menu_Code=DLPCourseDetails&EVS_Id=202&ActiveMenu=83&Opendivs=s18,s34 18:45-19:15 Jonny Hesthammer, Rocksource: "Use of CSEM technology in seismic exploration" The CSEM technology is rapidly gaining popularity and acceptance in the oil industry. However, it is difficult to understand the true value-of-information from the technology as the use of CSEM for exploration purposes is still in an early development phase. There are many uncertainties associated with the technology and the failure ot understand these can lead to non-optimal exploration strategies. Rocksource is an oil company that focusses on how to use CSEM technology and the associated value-of-information as a driver for the company's exploration activities. 19:15-19:30 Break 19:30-20:15 Rune Mittet, EMGS: CMP Inversion of Marine CSEM Data. We introduce a CMP-inversion algorithm for SBL data. The scheme provides promising results for data acquired over a recent discovery in South-East Asia. A major advantage with the method is that it is numerically very efficient. We stress that this is not a stand-alone method due to the simplifying pre-assumptions - proper 3D forward modeling is required for model verification in a post-processing step. 20:30 Social gathering. Location: Felix konferansesenter, Bryggetorget 3, Oslo (click here for a map). Food and drinks provided following the seminar. Welcome! NOTE: PRIOR REGISTRATION FOR THE MEETING IS MANDATORY.

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