Application of multifocusing method for an irregular topography imaging

摘要

A stack of records becomes one of the main steps in modern seismic data processing. In the stack procedure, the crucial operation is time correction. Conventional methods, e.g., normal moveout (NMO) and dip moveout (DMO) stack require a sufficiently accurate macro-velocity model. Whereas multifocusing imaging method does not depend on a macro-velocity model. The multifocusing method proposed by Gelchinsky belongs to a group of methods that can be characterized as macro-model-independent imaging methods. The multifocusing method represents a transformation of 2-D multicoverage reflection data into a simulated zero-offset stack profile. This transformation is based on a completely data-derived spatial stacking operator, and includes stacking large supergathers of seismic traces, each of which can span many CMP gathers. By extending the multifocusing moveout formula to explicitly account for nonezero elevations of the source and receiver, multifocusing imaging method can yield appropriate results when seismic data are acquired over an irregular topography. In recent years, many applications of multifocusing imaging over an irregular topography have demonstrated its advantages in comparison with conventional CMP processing. This paper will illustrate the corresponding formulas to a synthetic data example modeled by wave equation finite difference method. A real data imaging with irregular topography will also be performed using the developed method.