A self-supervised scheme for ground roll suppression

In recent years, self-supervised procedures have advanced the field of seismic noise attenuation, due to not requiring a massive amount of clean labeled data in the training stage, an unobtainable requirement for seismic data. However, current self-supervised methods usually suppress simple noise types, such as random and trace-wise noise, instead of the complicated, aliased ground roll. Here, we propose an adaptation of a self-supervised procedure, namely, blind-fan networks, to remove aliased ground roll within seismic shot gathers without any requirement for clean data. The self-supervised denoising procedure is implemented by designing a noise mask with a predefined direction to avoid the coherency of the ground roll being learned by the network while predicting one pixel's value. Numerical experiments on synthetic and field seismic data demonstrate that our method can effectively attenuate aliased ground roll.Comment: 19 pages, 12 figures

Improving the virtual‐source method by wavefield separation

The virtual source method has recently been proposed to image and monitor below complex and time-varying over-burden. The method requires surface shooting recorded at downhole receivers placed below the distorting or changing part of the overburden. Redatuming with the measured Green’s function allows the reconstruction of a complete downhole survey as if the sources were also buried at the re-ceiver locations. There are still some challenges that need to be addressed in the virtual source method, such as limited ac-quisition aperture and energy coming from the overburden. We demonstrate that up-down wavefield separation can sub-stantially improve the quality of virtual source data. First, it allows us to eliminate artifacts associated with the limited ac-quisition aperture typically used in practice. Second, it allows us to reconstruct a new optimized response in the absence of downgoing reflections and multiples from the overburden. These improvements are illustrated on a synthetic data set of a complex layered model modeled after the Fahud field in Oman, and on ocean-bottom seismic data acquired in the Mars field in the deepwater Gulf of Mexico

A New Algorithm of Iterative MIMO Detection and Decoding Using Linear Detector and Enhanced Turbo Procedure in Iterative Loop

In the paper we develop and evaluate a novel low complexity algorithm of iterative detection and decoding in multiple input multiple output (MIMO) system. It is based on a new enhanced Turbo procedure. Although the algorithm utilizes well-known components such as linear minimum mean square error (MMSE) detector and channel decoder with soft bits feedback, the new original procedure of getting extrinsic data essentially allows improving the receiver performance and reducing its complexity. Moreover, it is shown that proposed Turbo approach works even without channel decoder in the iteration loop. Thus, we ob-tain pure iterative MMSE detector with improved performance. Utilization of combined scheme with MMSE detector and channel decoder feedback demonstrates really outstanding performance. It is confirmed with simulations that the performance of proposed architecture exceeds traditional ML MIMO detector schemes that are designed with channel decoder but without iterative loop

Modeling of wave dispersion along cylindrical structures using the spectral method

Algorithm and code are presented that solve dispersion equations for cylindrically layered mediaconsisting of an arbitrary number of elastic and fluid layers. The algorithm is based on the spectralmethod which discretizes the underlying wave equations with the help of spectral differentiationmatrices and solves the corresponding equations as a generalized eigenvalue problem. For a givenfrequency the eigenvalues correspond to the wave numbers of different modes. The advantage ofthis technique is that it is easy to implement, especially for cases where traditional root-findingmethods are strongly limited or hard to realize, i.e., for attenuative, anisotropic, and poroelasticmedia. The application of the new approach is illustrated using models of an elastic cylinder and afluid-filled tube. The dispersion curves so produced are in good agreement with analytical results,which confirms the accuracy of the method. Particle displacement profiles of the fundamental mode in a free solid cylinder are computed for a range of frequencies