Abstract

We have developed a migration scheme that can compensate absorption and dispersion with effective Q estimation and Fresnel zone identification based on deep learning. We use the U-Net neural network technology in deep learning to automatically identify Fresnel zones from compensated migrated dip-angle gathers and obtain the optimal aperture for migration, avoiding the tedious task of manually modifying the boundaries of Fresnel zones. Instead of the interval Q factor, we used an effective Q parameter to compensate absorption and dispersion. The effective Q is estimated using VSP well data and surface seismic velocity data. The proposed scheme can be incorporated into conventional seismic data processing workflow. A field data set was employed to validate the proposed scheme. Higher resolution imaging results with low noise levels are obtained.

Highlights

  • The dissipation of seismic energy is caused by the anelasticity of the subsurface medium, which will decrease the amplitude and modify the phase

  • Cheng et al (2020) used a modified VGGNet (A convolutional neural network was developed by the University of Oxford’s Visual Geometry Group and Google DeepMind in 2014) to extract Fresnel zones from migrated dip-angle gathers, which is a useful attempt at deep learning for Fresnel zone estimation

  • This article takes the estimations of the optimal aperture and effective Q model as the research focus in the compensated prestack time migration (PSTM), which is arranged as follows: first, we introduce a modified PSTM scheme with compensation based on the effective Q; second, we propose a Fresnel zone identification scheme based on compensated migrated dip-angle gathers using deep learning; third, we present an estimation approach of the effective Q model for the compensated PSTM

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Summary

INTRODUCTION

The dissipation of seismic energy is caused by the anelasticity of the subsurface medium, which will decrease the amplitude and modify the phase. Cheng et al (2020) used a modified VGGNet (A convolutional neural network was developed by the University of Oxford’s Visual Geometry Group and Google DeepMind in 2014) to extract Fresnel zones from migrated dip-angle gathers, which is a useful attempt at deep learning for Fresnel zone estimation. This article takes the estimations of the optimal aperture and effective Q model as the research focus in the compensated PSTM, which is arranged as follows: first, we introduce a modified PSTM scheme with compensation based on the effective Q; second, we propose a Fresnel zone identification scheme based on compensated migrated dip-angle gathers using deep learning; third, we present an estimation approach of the effective Q model for the compensated PSTM. We demonstrate our scheme with a field data set

PSTM WITH COMPENSATION BASED ON EFFECTIVE Q
IDENTIFICATION OF FRESNEL ZONES USING DEEP LEARNING
Review of Migrated Dip-Angle Gathers
U-Net Architecture
Loss Function and Training
ESTIMATION OF EFFECTIVE Q
Field Data Example
Findings
CONCLUSION
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