Objective
The project aims at demonstrating the effectiveness of the approach developed by IFP's KIM consortium for post- and prestack imaging of complex structures.
Correct seismic imaging of geological structures is at the basis for reliable geological interpretaion of
- the likelihood of the subsurface to bear hydrocarbons
- the size of hydrocarbon bearing structures.
Both information are of crucial importance for the choice wether to develop a potential oil/gas field, where to place wells, how many wells need to be drilled etc. The more reliable the information is, the better the decisions can be taken under financial, technical and environmental considerations. The competitor with the better information will have considerable advantages for providing oil/gas at low cost.
The project allows to test for the first time on real data the innovative approach developed by IFP's KIM consortium for solving the post- and prestack imaging problem for complex geologies.
Seismic imaging of complex geologies requires the use of very expensive prestack depth migration technology and the availability of a very accurate subsurface velocity model. IFP's KIM consortium proposes an approach for the determination of such velocity models based on reflection tomography (inversion of reflection traveltimes)
The method can be applied in two regimes :poststack (zero offset) tomography and prestack (multi offset) tomography. The first one allows to refine a velocity model so as to satisfy the kinematic zero offset information as well as the geological a priori information available about the subsurface. The model found will thus be considered with the kinematics of the data, in others words, poststack depth imaging will yield a result satisfying the interpreter's a priori knowledge and the geophysicist's traveltime information. Amongst other things, testing of hypotheses about the geology of the subsurface will be possible.
The prestack regime allows to calculate velocities directly from the multi offset kinematics (travel times) contained in the seismic data. The resulting velocity model will satisfy this kinematic information (as well as any geological information provided as a priori information) and thus prestack depth migration will produce an optimal result because events in migration coherency panels are automatically flat. Before the application of reflection tomography, the seismic data has to be interpreted in terms of reflection traveltimes. This interpretation has to be performed in the poststack (zero offset) domain or/and in the multi-offset domain. Interpretation know-how and a priori geological/geophysical knowledge of the specific dataset is of prime importance during this step.
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DEM - Demonstration contractsCoordinator
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