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Dell'Aversana, P.
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- PublicationOpen AccessQuantitative seimsic imaging of complex structures for seismic hazard estimation and for reservoir characterization: a key strategy(2003-09-22)
; ; ; ; ;Virieux, J.; UMR Geosciences Azur, CNRS, Nice ;Operto, S.; UMR Geosciences Azur, CNRS, Nice ;Improta, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Dell'Aversana, P.; Eni, S.p.a., Milano, Italia; ; ; ; ; ; ; ;Pecce, M.; Università degli Studi del Sannio ;Manfredi, G.; Università degli Studi di Napoli ;Zollo, A.; Università degli Studi di Napoli; ; Seismic imaging of complex structures remains a challange, while sub-surface characterization becomes a crucial issue for safety, resources and wastes. When highly dense seismic profiles are available, global offset data can be simultaneously used for a full waveform inversion with the background initial Vp model provided by traveltime tomography. We show an application of combined traveltime and full-waveform tomographies performed on global offset crustal data collected in Southern Italy.145 162 - PublicationOpen AccessNon-linear 2-D traveltime inversion in complex media: application to the Southern Apennines (Italy)(2001)
; ; ; ; ; ;Improta, L.; Dipartimento di Scienze Fisiche, Università di Napoli, Napoli, Italy ;Herrero, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Zollo, A.; Dipartimento di Scienze Fisiche, Università di Napoli, Napoli, Italy ;Dell'Aversana, P.; Enterprise Oil Italiana, S.p.A, Roma ;Morandi, S.; Enterprise Oil Italiana, S.p.A, Roma; ; ; ; A new traveltime inversion method based on a non linear approach and multi scale process has been applied to a seismic data set acquired with a non conventional acquisition layout in a thrust-belt region. First arrivals and a main reflected phase have been hand picked. A first inversion is realized with only the first arrival traveltimes in order to obtain a 2D velocity image. The latter has been then used as background model for the interpretation of the reflected phase using another non linear multi scale inversion technique. Finally, the whole data set has been jointly inverted. The final velocity images are compared in order to assess the resolution and smearing effect. Moreover, the availability of a VSP survey allows us to independently assess the reliability of our results157 149 - PublicationOpen AccessDepth model building by constrained magnetotelluric inversion(2002)
; ; ;Dell'Aversana, P.; Enterprise Oil Italiana S.p.A., Roma, Italy ;Morandi, S.; Enterprise Oil Italiana S.p.A., Roma, Italy; In this paper we describe an approach aimed at integrating seismic and magnetotelluric data in a complex geological setting, characterised by thrust structures, in Southern Apennine, Southern Italy. Seismic data were collected by the «Global Offset» technique that is designed to record hight fold data in a wide range of offsets, without losing the benefit of near vertical reflection seismic. First arrivals picked from short to long offsets and the main reflections were inverted in order to produce a tomographic velocity-interface model. It was converted into a resistivity section applying an empirical relationship, obtained by well logs, between resistivity and velocity. That section was used as a reliable reference model for 2D inversion of magnetotelluric data collected along a parallel section very close to the seismic profile. The process was iterative and interactive and was aimed at producing consistent velocity and resistivity sections, honouring seismic and MT data set. The final MT model fits very well the observed apparent resistivity and phase, reproduces the main geological trends and its constrained by a well drilled close to the line.116 318 - PublicationOpen AccessMultiscale imaging of complex structures from multi-fold wide-aperture seismic data by frequency-domain full-waveform inversion: application to a thrust belt(2004-08-02)
; ; ; ; ; ; ;Ravaut, C.; UMR Gescience Azur, CNRS, Villefrance-sur-mer, France ;Operto, S.; UMR Gescience Azur, CNRS, Villefrance-sur-mer, France ;Improta, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Virieux, J.; UMR Gescience Azur, CNRS, Villefrance-sur-mer, France ;Herrero, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Dell'Aversana, P.; ENI S.p.A., San Donato Milanese, Milano, Italy; ; ; ; ; An application of full-waveform tomography to dense onshore wide-aperture seismic data recorded in a complex geological setting (thrust belt) is presented. The waveform modelling and tomography are implemented in the frequency domain. The modelling part is solved with a finite-difference method applied to the visco-acoustic wave equation. The inversion is based on a local gradient method. Only the P-wave velocity is involved in the inversion. The inversion is applied iteratively to discrete frequency components by proceeding from low to high frequencies. This defines a multiscale imaging in the sense that high wavenumbers are progressively incorporated in images. The linearized waveform tomography requires an accurate starting velocity model that has been developed by first-arrival traveltime tomography. After specific pre-processing of the data, 16 frequency components ranging between 5.4 and 20 Hz were inverted. Ten iterations were computed per frequency component leading to 160 tomographic models. The waveform tomography has successfully imaged southwest dipping structures previously identified from other geophysical data as being associated with high-resistivity bodies. The relevance of the tomographic images is locally demonstrated by comparison of a velocity–depth function extracted from the waveform tomography models with a coincident vertical seismic profiling (VSP) log available on the profile. Moreover, comparison between observed and synthetic seismograms computed in the (starting) traveltime and waveform tomography models demonstrates unambiguously that the waveform tomography successfully predicts for wide-angle reflections from southwest-dipping geological structures. This study demonstrates that the combination of first-arrival traveltime and frequency domain full-waveform tomographies applied to dense wide-aperture seismic data is a promising approach to quantitative imaging of complex geological structures. Indeed, wide-aperture acquisition geometries offer the opportunity to develop an accurate background velocity model for the subsequent waveform tomography. This is critical, because the building of the macromodel remains an open question when only near-vertical reflection data are considered.183 114 - PublicationRestrictedDepth and morphology of reflectors from the non-linear inversion of arrival times and waveforms semblance data. Part II: Modelling and interpretation of real data acquired in Southern Apennines, Italy(2008-10)
; ; ; ; ; ;Corciulo, M.; Dipartimento di Scienze Fisiche, Università di Napoli Federico II ;Zollo, A.; Dipartimento di Scienze Fisiche, Università di Napoli Federico II ;Vassallo, M.; Dipartimento di Scienze Fisiche, Università di Napoli Federico II ;Dell'Aversana, P.; Eni E&P ;Morandi, S.; Shell International Exploration and Production; ; ; ; In order to retrieve a 2D background velocity model and to retrieve the geometry and depth of shallow crustal reflectors in the Southern Apennines thrust belt a separate inversion of first arrival traveltimes and reflected waveforms was performed. Data were collected during an active seismic experiment in 1999 by Enterprise Oil Italiana and Eni-Agip using a global offset acquisition geometry. A total of 284 on-land shots were recorded by 201 receivers deployed on an 18 km line oriented SW–NE in the Val D’Agri region (Southern Apennines, Italy). The two-step procedure allows for the retrieval of a reliable velocity model by using a non-linear tomographic inversion and reflected waveform semblance data inversion. The tomographic model shows that the P wave velocity field varies vertically from approximately 3 km/s to 6 km/s within 4 km from the Earth’s surface. Moreover, at a distance of approximately 11 km along the profile, there is an abrupt increase in the velocity field. In this zone indeed, an ascent from 2 km depth to 0 km above sea level of the 5.2 km/s iso-velocity contour can be noted. The retrieved velocity can be associated with Plio-Pleistocene clastic deposits outcropping in the basin zone and with Mesozoic limestone deposits. The inversion of waveform semblance data shows that a P-to-P reflector is retrieved at a depth of approximately 2 km. This interface is deeper in the north-eastern part of the profile, where it reaches 3 km depth and can be associated with a limestone horizon.254 28 - PublicationRestrictedSeismic imaging of complex structures by non-linear traveltime inversion of dense wide-angle data: application to a thrust belt(2002-05-07)
; ; ; ; ; ; ;Improta, L.; Dipartimento di Scienze Fisiche, Università di Napoli, Napoli, Italy ;Zollo, A.; Dipartimento di Scienze Fisiche, Università di Napoli, Napoli, Italy ;Herrero, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Frattini, R.; Dipartimento di Scienze Fisiche, Università di Napoli, Napoli, Italy ;Virieux, J.; UMR Geoscience Azur, CNRS, Villefrance-sur-mer, France ;Dell'Aversana, P.; Enterprise Oil Italiana, S.p.A., Via due Macelli, Roma, Italy; ; ; ; ; A dense wide-angle data set is used to test a two-step procedure for the separate inversion of first-arrival and reflection traveltimes. Data were collected in a complex thrust belt environment (southern Italy) along a 14 km line, with closely spaced sources (60 m) and receivers (90 m). A fully non-linear tomographic technique, that is specially designed to image complex structures, is applied to over 6400 first-arrival traveltimes in order to determine a detailed velocity model. A bi-cubic spline velocity model parameterization is used. The inversion strategy follows a multiscale approach and employs a non-linear velocity optimization scheme. The tomographic velocity model is adopted as the background reference medium for a subsequent interface inversion, which is aimed at imaging a target upper-crust reflector. The interface inversion method is also based on a multiscale approach and uses a non-linear technique for model parameters (interface position nodes) optimization. It is applied to over 1600 reflection traveltimes of a target event picked both in the near- and in the wide-angle offset range. The retrieved interface is well resolved in central part of the model, where ray coverage mainly includes clear post-critical reflections and the background velocity model is accurate in depth thanks to large offset deep turning rays. The determined velocity and interface models are consistent with VSP data and correlate well with the geometry of known geologic structures. This study shows that the used inversion approach is efficient for target-orientated investigations in complex geologic environments158 28 - PublicationOpen AccessQuantitative imaging of complex structures from multi-fold wide-aperture seismic data: a case study(2004-07-01)
; ; ; ; ; ; ;Operto, S.; UMR Geoscience Azur, CNRS, Villefrance-sur-Mer, France ;Ravaut, C.; UMR Geoscience Azur, CNRS, Villefrance-sur-Mer, France ;Improta, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Virieux, J.; UMR Geoscience Azur, CNRS, Villefrance-sur-Mer, France ;Herrero, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Dell'Aversana, P.; ENI S.p.A S.Donato Milanese, Milano, Italy; ; ; ; ; An integrated multi-scale seismic imaging flow including first-arrival traveltime tomography and waveform inversion is applied to dense onshore wide-aperture seimsic data recorded in a complex geological setting (southern Apennines thrust belt, Italy)206 73