Inspiration for Seismic Diffraction Modelling, Separation, and Velocity in Depth Imaging

Yasir Bashir,Deva Prasad Ghosh,Syed Haroon Ali,Nordiana Mohd Muztaza,Seyed Yaser Moussavi Alashloo

doi:10.3390/app10124391

Abstract

Fractured imaging is an important target for oil and gas exploration, as these images are heterogeneous and have contain low-impedance contrast, which indicate the complexity in a geological structure. These small-scale discontinuities, such as fractures and faults, present themselves in seismic data in the form of diffracted waves. Generally, seismic data contain both reflected and diffracted events because of the physical phenomena in the subsurface and due to the recording system. Seismic diffractions are produced once the acoustic impedance contrast appears, including faults, fractures, channels, rough edges of structures, and karst sections. In this study, a double square root (DSR) equation is used for modeling of the diffraction hyperbola with different velocities and depths of point diffraction to elaborate the diffraction hyperbolic pattern. Further, we study the diffraction separation methods and the effects of the velocity analysis methods (semblance vs. hybrid travel time) for velocity model building for imaging. As a proof of concept, we apply our research work on a steep dipping fault model, which demonstrates the possibility of separating seismic diffractions using dip frequency filtering (DFF) in the frequency–wavenumber (F-K) domain. The imaging is performed using two different velocity models, namely the semblance and hybrid travel time (HTT) analysis methods. The HTT method provides the optimum results for imaging of complex structures and imaging below shadow zones.

Highlights

Seismic diffraction events are produced because of small-scale elements in the subsurface, such as faults, fractures, channels, and rough edges of salt bodies; or because of small changes in the seismic reflectivity, such as those produced by fluid occurrence or fluid movement in the period of production.These diffracted waves contain the most important information for subsurface discontinuities [1].The diffraction theory sometimes makes it impossible to understand the qualitative properties of diffraction phenomena [2]
We found thatparameters three parameters have essential on diffraction behavior, the velocity, depth, and frequency of the seismic wave
The need for a diffraction separation method was studied and a dip frequency filter (DFF) filtering technique was introduced for diffraction separation and method was studied and a DFF filtering technique was introduced for diffraction separation and imaging

Summary

Introduction

Seismic diffraction events are produced because of small-scale elements in the subsurface, such as faults, fractures, channels, and rough edges of salt bodies; or because of small changes in the seismic reflectivity, such as those produced by fluid occurrence or fluid movement in the period of production.These diffracted waves contain the most important information for subsurface discontinuities [1].The diffraction theory sometimes makes it impossible to understand the qualitative properties of diffraction phenomena [2]. Seismic diffraction events are produced because of small-scale elements in the subsurface, such as faults, fractures, channels, and rough edges of salt bodies; or because of small changes in the seismic reflectivity, such as those produced by fluid occurrence or fluid movement in the period of production. These diffracted waves contain the most important information for subsurface discontinuities [1]. The diffraction theory sometimes makes it impossible to understand the qualitative properties of diffraction phenomena [2] These diffraction data are used for travel time approximation for anisotropic imaging [3]. Amplitude preservation of seismic waves was achieved by Hilterman in

Objectives

Methods

Results

Conclusion