Disputas: Piyoosh Jaysaval
M. Tech. Piyoosh Jaysaval ved Fysisk institutt vil forsvare sin avhandling for graden ph.d: "Advances in 3D finite-difference modelling of electromagnetic Fields in the conductive Earth" "
Tid og sted for prøveforelesning
- Dr. Sofia Davydycheva, 3DEM Holding, Texas, USA
- Dr. Vladimir Puzyrev, Barcelona Supercomputing Centre, Barcelona, Spania
- Førsteamanuensis Øystein Prytz, Universitetet i Oslo, Oslo, Norge
Leder av disputas
Professor Jøran I. Moen
- Professor Anders Malthe-Sørenssen, Universitetet i Oslo
- Professor Joakim Bergli, Universitetet i Oslo
- Dr. Daniil Shantsev, EMGS
The central theme of this PhD research is the development of fast and accurate 3D forward modelling algorithms to calculate synthetic electromagnetic (EM) fields in complex geological settings.
Marine controlled-source electromagnetic (CSEM) surveying is now an important technique for petroleum exploration. The technique uses a strong electric current source to probe subsurface resistivities and has proven to be very useful for detecting resistive petroleum reservoirs. In this technique, the data are recorded in the form of electric and magnetic fields, which must be inverted to obtain an image of the subsurface resistivity distribution.
To recover a 3D, geologically consistent, resistivity image of subsurface, CSEM inversion algorithms usually require a significantly large number of forward simulation of CSEM responses over different resistivity models. Therefore, having a fast and accurate forward modelling scheme is a key ingredient for a reliable inversion and interpretation of the recorded CSEM data. Forward modeling also plays a crucial role in CSEM survey design, feasibility study, and post inversion modeling.
In this thesis, three novel 3D finite-difference (FD) EM modelling schemes have been developed and presented: (1) a Schur complement based fast multimodel FD modeling scheme developed to reduce total modeling time in a constrained inversion, (2) an exponential FD modeling scheme developed based on the oscillatory and exponentially decaying behaviors of the EM fields to get more accurate results or to reduce modeling time, and (3) an anisotropic FD modeling scheme developed to handle general electrical anisotropy of the earth. The schemes are also applied to inversion of CSEM data (e.g. from the North Sea and the Gulf of Mexico) to demonstrate their efficiency.
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Publisert 15. mars 2016 12:25
- Sist endret 15. mars 2016 13:45