The impact of full-waveform inversion for imaging “EWATS” streamer data in a complex salt environment: A case study in the Gulf of Mexico

2020 ◽  
Author(s):  
Peter Lanzarone ◽  
Xukai Shen ◽  
Gerchard Pfau ◽  
James Mika ◽  
Andrew Brenders ◽  
...  
Keyword(s):  
Gulf Of Mexico ◽  
Waveform Inversion ◽  
Complex Salt ◽  
Full Waveform Inversion ◽  
Full Waveform ◽  
Streamer Data ◽  
The Impact

Gas hydrate quantification using full-waveform inversion of sparse ocean-bottom seismic data: A case study from Green Canyon Block 955, Gulf of Mexico

Geophysics ◽  
2018 ◽  
Vol 83 (4) ◽  
pp. B167-B181 ◽  
Author(s):  
Jiliang Wang ◽  
Priyank Jaiswal ◽  
Seth S. Haines ◽  
Patrick E. Hart ◽  
Shiguo Wu
Keyword(s):  
Gulf Of Mexico ◽  
Gas Hydrate ◽  
Seismic Data ◽  
Waveform Inversion ◽  
Full Waveform Inversion ◽  
Ocean Bottom ◽  
Full Waveform ◽  
Sonic Log ◽  
Obs Data

We present a case study of gas hydrate quantification using dense short-offset multichannel seismic (MCS) and sparse long-offset ocean-bottom-seismometer (OBS) data in lease block Green Canyon 955 (GC955), Gulf of Mexico (GOM), where the presence of gas hydrate was interpreted using logging while drilling (LWD) data acquired by the GOM Gas Hydrate Joint Industry Project Leg II expedition. We use frequency-domain full-waveform inversion (FWI) of seven OBS gathers to invert for a P-wave velocity model of an approximately 7 km long MCS profile connecting two LWD sites, GC955-H and GC955-Q. We build the starting model for FWI using traveltime inversion (TI) of the MCS and OBS data. In addition, we use the TI model for depth migrating the MCS stack. At the LWD sites, we constrain the hydrate saturation ([Formula: see text]) using sonic and resistivity logs. Unfortunately, as is typical of seismic quantification problems, the FWI model resolution is not sufficient to extrapolate the LWD-based [Formula: see text]. Therefore, we apply Backus averaging to the sonic log, at 60 m wavelength, bringing it within approximately 8% of the FWI model and make the assumption that averaging the sonic log is same as redistributing the gas hydrate within the Backus wavelength. In this manner, instead of [Formula: see text], the FWI model is able to estimate the total gas hydrate volume. In the end, we use the FWI model and the migrated stack to constrain the locations and bulk volumes of free gas and gas hydrate. Our results demonstrate that with careful processing, reasonable estimates on locations and bulk volumes of submarine gas hydrate accumulations can be achieved even with sparse seismic data that are not adequate for amplitude-based assessments.

Full-waveform inversion for salt: A coming of age

2019 ◽  
Vol 38 (3) ◽  
pp. 204-213 ◽  
Author(s):  
Ping Wang ◽  
Zhigang Zhang ◽  
Jiawei Mei ◽  
Feng Lin ◽  
Rongxin Huang
Keyword(s):  
Waveform Inversion ◽  
Synthetic Data ◽  
Complex Salt ◽  
Full Waveform Inversion ◽  
Ocean Bottom ◽  
Very High Frequency ◽  
Velocity Models ◽  
Full Waveform ◽  
Streamer Data ◽  
Subsalt Imaging

Full-waveform inversion (FWI), proposed by Lailly and Tarantola in the 1980s, is considered to be the most promising data-driven tool for automatically building velocity models. Many successful examples have been reported using FWI to update shallow sediments, gas pockets, and mud volcanoes. However, successful applications of FWI to update salt structures had almost only been seen on synthetic data until recent progress at the Atlantis Field in the Gulf of Mexico. We revisited some aspects of FWI algorithms to minimize cycle-skipping and amplitude discrepancy issues and derived an FWI algorithm that is able to build complex salt velocity models. We applied this algorithm to a variety of data sets, including wide-azimuth and full-azimuth (FAZ) streamer data as well as ocean-bottom-node data, with different geologic settings in order to demonstrate the effectiveness of the method for salt velocity updates and to examine some fundamentals of the salt problem. We observed that, in multiple cases, salt velocity models from this FWI algorithm produced subsalt images of superior quality. We demonstrate with one FAZ streamer data example in Keathley Canyon that we do not necessarily need very high frequency in FWI for subsalt imaging purposes. Based on this observation, we envision that sparse node for velocity acquisition may provide appropriate data to handle large and complex salt bodies with FWI. We believe the combination of advanced FWI algorithms and appropriate data acquisition will bring a step change to subsalt imaging.

Time-lapse full waveform inversion based on curvelet transform: Case study of CO2 storage monitoring

2021 ◽  
Vol 110 ◽  
pp. 103417
Author(s):  
Dong Li ◽  
Suping Peng ◽  
Xingguo Huang ◽  
Yinling Guo ◽  
Yongxu Lu ◽  
...  
Keyword(s):  
Co2 Storage ◽  
Waveform Inversion ◽  
Curvelet Transform ◽  
Time Lapse ◽  
Full Waveform Inversion ◽  
Full Waveform

Reflection Full Waveform Inversion of Walkaway VSP – Abu Dhabi Case Study

2020 ◽  
Author(s):  
A. Shigematsu ◽  
Y. Nakamura ◽  
A. Kato ◽  
T. Mouri ◽  
G. Sakata ◽  
...  
Keyword(s):  
Waveform Inversion ◽  
Abu Dhabi ◽  
Full Waveform Inversion ◽  
Full Waveform ◽  
Walkaway Vsp
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