Objetivo For both hydrocarbon exploration and production, reservoirs have to be characterised accurately for the structure and lithologic properties of rocks : so we could estimate fluid movements in reservoirs to enhance production. Seismic tomography can be used to get accurate P wave velocities. Once the velocity model is obtained, 3D amplitude preserving pre-stack depth migration, followed by Amplitude Versus Offset inversion (AVO), will yield an accurate structural image coupled with lithologic and fluid attributes. By applying this technology to time lapse 3D marine surveys (4D), we can monitor fluid movements in a producing reservoir and estimate the porosity and the hydraulic connectivity : these are critical for both reserves evaluation and optimal location of a new production wells.Three-component receivers, as in Ocean Bottom Cable (OBC) surveys, allow to record and separate P and S waves. Comparing the elastic Earth Model obtained by OBC with that one from conventional marine surveys, we will decide the benefits from OBC surveys in 4D technology. We will compare also the costs of one versus multi-component seismograms in real cases.The experience by synthetic data proved that the proposed approach is adequate for the 4-D analysis, and that anisotropy effects cannot be neglected. Furthermore, a very high precision is necessary in seismic tomography for imaging the fine details sought.An integrated system for AVO and tomographic inversion will be a precious tool for both seismic exploration and hydrocarbon production. It will provide a robust and reliable depth model in 3D from seismic data. By estimating the Vp/Vs ratio, and using 3D amplitude preserving pre-stack depth migration and AVO inversion, we will better characterise the reservoir interior. Most of the planned tools for seismic acquisition and processing are proven recent advances, but their integration is totally new. The joint 3D tomographic inversion of reflected, refracted and transmitted arrivals by adaptative irregular grids is a new technique, successfully tested recently. 4D seismics is an effective leading edge technology, which is still moving from a pioneering phase to an industrial application. 3D AVO migration/inversion can contribute to 4D seismics by providing very accurate structural depht images, coupled with lithological and fluid attributes. By using time-lapse 3D surveys(4D), we will couple the local variations of seismic signals to the fluid movements in a reservoir. Relating such anomalies with well production is crucial for enhancing the location of new wells, reducing their number and so the production costs.Three component seismograms provide direct information about the elastic properties of the Earth. 3D elastic inversion of three-component seismograms by tomography and AVO was never done at a large scale with real seismic data. Three component acquisition and processing at a large scale will enable us to compare the new estimates for Vp and Vs with those obtained by AVO migration/inversion from single component records, suggesting a tradeoff between costs and benefits. A decrease of the production costs will reflect directly on the European oil companies involved, increasing their competitiveness with respect to other international companies. First, some marginal fields in various European areas, not profitable at present, could become so by reducing the production costs. In addition, by increasing or stabilising the European hydrocarbon production with respect to the OPEC countries, one would contribute in maintaining the international oil prices at acceptable levels for the European industries that must import it. The planned system will be based on a workstation with adequate memory and I/O devices. Thus, it will be possible to carry out most data processing (not including 3-D pre-stack depth migration) in a not demanding environment. Ámbito científico natural sciencesearth and related environmental sciencesgeologylithologynatural scienceschemical sciencesorganic chemistryhydrocarbonsnatural sciencesearth and related environmental sciencesgeologyseismologynatural sciencescomputer and information sciencesdata sciencedata processing Programa(s) FP4-NNE-THERMIE C - Specific programme for research and technological development, including demonstration in the field of non-nuclear energy, 1994-1998 Tema(s) 1 - OIL AND GAS Convocatoria de propuestas Data not available Régimen de financiación DEM - Demonstration contracts Coordinador OGS Aportación de la UE Sin datos Dirección P.O.BOX 2011 34016 Trieste Italia Ver en el mapa Coste total Sin datos
