Ultra-fast diffraction separation in the five-dimensional domain 85th Eage Annual Conference and Exhibition 2024, 2024
QUANTIFYING ANISOTROPY PARAMETERS IN WEAKLY ANISOTROPIC MEDIA THROUGH DIFFRACTION TRAVELTIME PARAMETER CLUSTERS Tiago Antonio Alves Coimbra, Rodrigo Bloot, Alexandre William Camargo, Jorge Henrique Faccipieri Junior Revista Brasileira De Geofisica, 2024 The seismic response datasets obtained from anisotropic media present several challenges for established seismic processing methods. To determine whether wavefront interference stems from anisotropic effects, velocity model heterogeneity, or both remains a key challenge. While reflection signatures may be insufficient for distinguishing these attributes, diffraction information in seismic datasets often provides richer insights into subsurface structures. In response to these challenges, we propose a framework that explores the feasibility of using diffraction traveltime parameters as indicators of anisotropy. By introducing an average measurement velocity derived from a cluster of diffraction traveltime responses, defined as a function of the traveltime slopes estimated from the dataset, we aim to discern the prevalence of anisotropy, heterogeneity, or both within a target region. Experiments conducted with synthetic data designed to simulate realistic scenarios have yielded promising results.
High-performance computing strategies for seismic-imaging software on the cluster and cloud-computing environments Nicholas T. Okita, Alexandre W. Camargo, José Ribeiro, Tiago A. Coimbra, Caian Benedicto, et al. Geophysical Prospecting, 2022 Modern subsurface imaging techniques allow obtaining high‐quality images but with high computational costs. Nonetheless, depending on the amount of data, their execution is limited by memory in the current generation's hardware. However, with the advancement of new hardware and cloud‐based solutions, these problems are mitigated but still with the risk of work loss and instability. To mitigate the execution problems in memory‐limited and fail‐prone environments, we propose two high‐performance computing techniques. The first is based on independent checkpointing alongside a fault‐tolerant framework to store an execution state and recover from that state in case of failures. Besides, for memory‐limited graphics processing units, we present a technique to reduce the amount of memory requirement that we call the hybrid strategy. The experiments showed that the independent checkpointing alongside the fault‐tolerant framework is able to mitigate the performance penalty of node failures, with the independent checkpointing technique being more relevant when multiple nodes are terminated. Furthermore, the hybrid strategy technique has shown the possibility of execution of larger models that could make the graphics processing unit run out of memory otherwise. Finally, our implementation is scalable, allowing a significant improvement in performance when adding new nodes. In conclusion, our techniques can be used to deliver fast, high‐fidelity subsurface imaging in unstable and memory‐limited environments, such as the cloud.
Fast estimation of prestack common reflection surface parameters Anders U. Waldeland, Tiago A. Coimbra, Jorge H. Faccipieri, Anne H. Schistad Solberg, Leiv‐J. Gelius Geophysical Prospecting, 2019 We present a method for fast estimation of finite offset common reflection surface parameters. Firstly, the derivatives with respect to offset are derived from the velocity guide. Secondly, we apply structure tensors to extract the derivatives with respect to midpoint from stacked common offset sections. Finally, the mixed derivative is estimated using a one‐parametric semblance search. The proposed method is compared to the global five‐parametric semblance search and the pragmatic sequential two‐parametric semblance search on one synthetic and one real data set. The experiments show that the proposed method is more robust against noise than the pragmatic search and have comparable robustness with the global search. The proposed method smoothes parameter estimates in a local window, and the window size is set to give the best trade‐off between detail and robustness. Since the proposed method is dependent on a velocity guide, the quality of the other parameter estimates may be influenced by any inaccuracies in the guide. The main advantage of the proposed method is the computational efficiency. When compared with a gridded implementation of the semblance search, the proposed method is 10 and 400 times faster than the pragmatic and global search. Alternative search strategies significantly reduce the computational cost of the global search. However, since more than 99% of the computational cost of the proposed method comes from the semblance search to estimate the mixed derivative, it is expected that such techniques also reduce the computational cost for the proposed method.
Stretch-free generalized normal moveout correction Jorge H. Faccipieri, Tiago A. Coimbra, Rodrigo Bloot Geophysical Prospecting, 2019 The effective application of normal moveout correction processes mainly depends on four factors: the chosen traveltime approximation, the stretching associated with the given traveltime, crossing events and phase changes, the last two being inherent to the seismic data. In this context, we conduct a quantitative analysis on stretching considering a general traveltime expression depending on half‐offset and midpoint coordinates. Through this analysis, we propose a mathematically proven procedure to eliminate stretching, which can be applied to any traveltime approximation. The proposed method is applied to synthetic and real data sets, considering different traveltime approximations and achieved complete elimination of stretching.
Smoothing kinematic wavefield attributes to reduce random noise and enhance signal-tonoise ratio in seismic imaging 74th European Association of Geoscientists and Engineers Conference and Exhibition 2012 Incorporating SPE Europec 2012 Responsibly Securing Natural Resources, 2012
2-D pre- And post-stack diffraction separation and imaging Endrias G. Asgedom, Leiv -J. Gelius, J. H. Faccipieri, Martin Tygel Society of Exploration Geophysicists International Exposition and 82nd Annual Meeting 2012 Seg 2012, 2012
