Inverse spectral decomposition using an lp-norm constraint for the detection of close geological anomalies

San-Yi Yuan,Tie-Yi Wang,Jie Qi,Shan Yang,Shang-Xu Wang

doi:10.1007/s12182-020-00490-6

Abstract

An important application of spectral decomposition (SD) is to identify subsurface geological anomalies such as channels and karst caves, which may be buried in full-band seismic data. However, the classical SD methods including the wavelet transform (WT) are often limited by relatively low time–frequency resolution, which is responsible for false high horizon-associated space resolution probably indicating more geological structures, especially when close geological anomalies exist. To address this issue, we impose a constraint of minimizing an lp (0 < p < 1) norm of time–frequency spectral coefficients on the misfit derived by using the inverse WT and apply the generalized iterated shrinkage algorithm to invert for the optimal coefficients. Compared with the WT and inverse SD (ISD) using a typical l1-norm constraint, the modified ISD (MISD) using an lp-norm constraint can yield a more compact spectrum contributing to detect the distributions of close geological features. We design a 3D synthetic dataset involving frequency-close thin geological anomalies and the other 3D non-stationary dataset involving time-close anomalies to demonstrate the effectiveness of MISD. The application of 4D spectrum on a 3D real dataset with an area of approximately 230 km2 illustrates its potential for detecting deep channels and the karst slope fracture zone.

Highlights

Detecting anomalous bodies in the subsurface, such as channels, karst caves, faults and alluvial fans, is one of the key objectives in seismic exploration (e.g., Bacon et al 2003; Qi et al 2014; Kang et al 2020)
We investigate the potential application of a modified inverse SD (ISD) method with an lp-norm (0 < p < 1) constraint to detect close geological anomalies along the time direction or those at the frequency along a horizon
We use modified ISD (MISD) based on an lp-norm constraint of spectral coefficients to detect different geological bodies, which can reach a higher energy concentration in the

Summary

Introduction

Detecting anomalous bodies in the subsurface, such as channels, karst caves, faults and alluvial fans, is one of the key objectives in seismic exploration (e.g., Bacon et al 2003; Qi et al 2014; Kang et al 2020). These geological anomalies will be conductive to the construction of traps and reservoirs in the Earth, since they can usually provide storage space and migration channel for oil and natural gas Decomposing seismic data into certain modes with different dominant frequencies and bandwidth can facilitate extracting intrinsic spectral features (e.g., Li et al 2017; Liu et al 2019)

Methods

Discussion

Conclusion