Improving subsalt reservoir imaging with reflection FWI: An OBN case study at Conger field,  Gulf of Mexico

Lin, Feng; Asmerom, B.; Huang, Ronald; Kuntz, Brad; Gehman, Carter; Tanis, Mehmet C.

doi:10.1190/segam2018-2996264.1

Cited by 5 publications

(2 citation statements)

References 12 publications

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“…In the active-source seismic datasets, the number of shots could simply reach several thousand, and the computing resources directly control the applicability of the FWI on the field datasets. Nowadays, high-performance computing servers allow for the industrial-scale application of FWI on 2D/3D seismic data (Brown et al, 2019;Dickinson et al, 2017;Landolsi et al, 2016;Lin et al, 2018;Tiwari & Mao, 2018).…”

Section: Introductionmentioning

confidence: 99%

Full-Waveform Inversion for Imaging Faulted Structures: A Case Study from the Japan Trench Forearc Slope

Hondori

Guo

Mikada

et al. 2021

Pure Appl. Geophys.

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Full-waveform inversion (FWI) of limited-offset marine seismic data is a challenging task due to the lack of refracted energy and diving waves from the shallow sediments, which are fundamentally required to update the long-wavelength background velocity model in a tomographic fashion. When these events are absent, a reliable initial velocity model is necessary to ensure that the observed and simulated waveforms kinematically fit within an error of less than half a wavelength to protect the FWI iterative local optimization scheme from cycle skipping. We use a migration-based velocity analysis (MVA) method, including a combination of the layer-stripping approach and iterations of Kirchhoff prestack depth migration (KPSDM), to build an accurate initial velocity model for the FWI application on 2D seismic data with a maximum offset of 5.8 km. The data are acquired in the Japan Trench subduction zone, and we focus on the area where the shallow sediments overlying a highly reflective basement on top of the Cretaceous erosional unconformity are severely faulted and deformed. Despite the limited offsets available in the seismic data, our carefully designed workflow for data preconditioning, initial model building, and waveform inversion provides a velocity model that could improve the depth images down to almost 3.5 km. We present several quality control measures to assess the reliability of the resulting FWI model, including ray path illuminations, sensitivity kernels, reverse time migration (RTM) images, and KPSDM common image gathers. A direct comparison between the FWI and MVA velocity profiles reveals a sharp boundary at the Cretaceous basement interface, a feature that could not be observed in the MVA velocity model. The normal faults caused by the basal erosion of the upper plate in the study area reach the seafloor with evident subsidence of the shallow strata, implying that the faults are active.

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Section: Introductionmentioning

confidence: 99%

Full-Waveform Inversion for Imaging Faulted Structures: A Case Study from the Japan Trench Forearc Slope

Hondori

Guo

Mikada

et al. 2021

Pure Appl. Geophys.

View full text Add to dashboard Cite

show abstract

“…In the active-source seismic datasets, the number of shots could simply reach several thousand, and the computing resources directly control the applicability of the FWI on the eld datasets. Nowadays, the high performance computing servers allow the industrial-scale application of FWI on 2D/3D seismic data (Landolsi et al 2016;Dickinson et al 2017;Lin et al 2018;Tiwari et al 2018;Brown et al 2019).…”

Section: Introductionmentioning

confidence: 99%

Full Waveform Inversion for Imaging Faulted Structures; a Case Study from Japan Trench Forearc Slope

Hondori

Chen

Mikada

et al. 2021

Preprint

View full text Add to dashboard Cite

Full waveform inversion (FWI) of limited-offset marine seismic data is a challenging task due to the lack of refracted energy and diving waves from the shallow sediments, which are fundamentally required to update the long-wavelength background velocity model through a tomographic fashion. When these events are absent, a reliable initial velocity model is necessary to assure that the observed and simulated waveforms kinematically fit within an error less than half a wavelength to protect the FWI iterative local optimization scheme from cycle skipping. We use a migration-based velocity analysis (MVA) method, including a combination of the layer stripping approach and iterations of Kirchhoff prestack depth migration (KPSDM) to build an accurate initial velocity model for the FWI application on 2D seismic data with a maximum offset of 5.8 km. The data is acquired in the Japan Trench subduction zone, and we focus on the area where the shallow sediments overlying a highly reflective basement on top of the Cretaceous erosional unconformity are severely faulted and deformed. Despite the limited offsets available in the seismic data, our carefully designed workflow for data preconditioning, initial model building, and waveform inversion provides a velocity model which could improve the depth images down to a depth of almost 3.5 km. We present several quality control measures to assess the reliability of the resulting FWI model, including ray path illuminations, sensitivity kernels, reverse time migration (RTM) images, and KPSDM common image gathers. A direct comparison between the FWI and MVA velocity profiles reveals a sharp boundary at the Cretaceous basement interface, a feature which could not be observed in the MVA velocity model. The normal faults caused by the basal erosion of the upper plate in the study area reach the seafloor with evident subsidence of the shallow strata, implying that the faults are active.

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Innovative application of full-waveform inversion applied to extended wide-azimuth marine streamer seismic data in a complex salt environment

et al. 2022

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We demonstrated the application of full-waveform inversion (FWI) guided velocity model building to an extended wide-azimuth towed streamer (EWATS) seismic data set in the Gulf of Mexico. Field data were collected over a historically challenging imaging area, colloquially called the “grunge zone” due to the formation of a compressional allosuture emplaced between two colliding salt sheets. These data had a poor subsalt image below the suture with conventional narrow-azimuth data. Additional geologic complexities were observed including high-velocity carbonate carapace near the top of salt and multiple intrasalt sedimentary inclusions. As such, improved seismic imaging was required to plan and execute wells targeting subsalt strata. Significant improvements to the velocity model and subsalt image were evident with wide-azimuth towed streamer and later EWATS data using conventional top-down velocity model building approaches. Then, high-impact improvements were made using EWATS data with an FWI velocity model building workflow; this study represented an early successful application of FWI used to update salt body geometries from streamer seismic data, in which many past applications were limited to improving sedimentary velocities. Later petrophysical data verified the new FWI-derived model, which had significantly increased confidence in the structural and stratigraphic interpretation of subsalt reservoir systems below the grunge zone.

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Improving subsalt reservoir imaging with reflection FWI: An OBN case study at Conger field, Gulf of Mexico

Cited by 5 publications

References 12 publications

Full-Waveform Inversion for Imaging Faulted Structures: A Case Study from the Japan Trench Forearc Slope

Full-Waveform Inversion for Imaging Faulted Structures: A Case Study from the Japan Trench Forearc Slope

Full Waveform Inversion for Imaging Faulted Structures; a Case Study from Japan Trench Forearc Slope

Innovative application of full-waveform inversion applied to extended wide-azimuth marine streamer seismic data in a complex salt environment

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