Seismic scattering resolution analysis of subwavelength scale fractures
Accurately identifying the seismic characteristics of fractured reservoirs has become one of the main challenges in current seismic exploration,especially for deep reefs or carbonate reservoirs,which are mostly sub-wavelength scale and cannot be fully resolved using the traditional quarter-wavelength geometric resolution criteria of seismic reflection.Traditional methods for studying the seismic responses of fractures mainly rely on anisotropic equivalent medium theory.This paper proposes a wavenumber-domain scattering imaging matrix method based on the scattering focusing resolution analysis theory to characterize the spatial distribution and morphological characteristics of fracture systems.Specifically,this method calculates the differences in amplitude and structure between wavenumber-domain imaging matrices with and without fractures.This paper analyzes the seismic recognizability of sub-wavelength scale fractures from the perspectives of scattering energy and anisotropy.Numerical cases under uniform and complex background media demonstrate that amplitude differences are better suited for identifying the thickness and density of fractures,while structure differences are better suited for identifying the angle of fractures.The paper also discusses how complex media,random noise and array length affect the seismic scattering recognizability of fracture systems.The array length has minimal effect on the response of fracture thickness,but it significantly affects the recognition of high-angle fractures.Therefore,it is necessary that the array length be at least three times the target depth.
NETL
NSTL
万方数据
维普
