Bulletin of the Geological Society of Malaysia, Volume 72, November 2021, pp. 113 – 122

Application of finite difference eikonal solver for traveltime computation in forward modeling and migration

Amir Mustaqim Majdi^1,*, Seyed Yaser Moussavi Alashloo², Nik Nur Anis Amalina Nik Mohd Hassan¹, Abdul Rahim Md Arshad¹, Abdul Halim Abdul Latiff¹

1 Centre for Subsurface Seismic Imaging, Department of Geosciences, Universiti Teknologi PETRONAS, 32610 Seri Iskandar, Perak, Malaysia
2 Institute of Geophysics, Polish Academy of Sciences, 01-452 Warsaw, Poland
* Corresponding author email address: amir_17008708@utp.edu.my

Abstract: Traveltime is one of the propagating wave’s components. As the wave propagates further, the traveltime increases. It can be computed by solving wave equation of the ray path or the eikonal wave equation. Accurate method of computing traveltimes will give a significant impact on enhancing the output of seismic forward modeling and migration. In seismic forward modeling, computation of the wave’s traveltime locally by ray tracing method leads to low resolution of the resulting seismic image, especially when the subsurface is having a complex geology. However, computing the wave’s traveltime with a gridding scheme by finite difference methods able to overcomes the problem. This paper aims to discuss the ability of ray tracing and fast marching method of finite difference in obtaining a seismic image that have more similarity with its subsurface model. We illustrated the results of the traveltime computation by both methods in form of ray path projection and wavefront. We employed these methods in forward modeling and compared both resulting seismic images. Seismic migration is executed as a part of quality control (QC). We used a synthetic velocity model which based on a part of Malay Basin geology structure. Our findings shows that the seismic images produced by the application of fast marching finite difference method has better resolution than ray tracing method especially on deeper part of subsurface model.

Keywords: Reflection, traveltime, forward modeling, ray tracing, eikonal equation, gridding scheme, fast marching, finite difference method, migration

DOI: https://doi.org/10.7186/bgsm72202109