The Study Of Wave Equation Based Analysis Of Seismic Acquisition Parameters And Application

The seismic data acquisition, processing and interpretation are integrated project and interacted. Data acquisition is the base of seismic exploration. The conventional seismic geometry design is based on the assumption of horizontal layered subsurface media. This assumption usually can not fit to the situations of complicated surface and subsurface structures. The methodological study of wave-equation-theory based seismic acquisition parameter analysis and geometry design has important theoretical meaning and practical value for the improvement of seismic image quality with complicated structure and lithology.This paper has studied the effects of typical near-surface velocity models to the seismic wave field and energy by theoretical analysis, numeral emulation and practical application. We also studied wave-equation-based seismic illumination and resolution analysis. These studies can provide significant referenced data for quantitative evaluation of seismic acquisition parameters. The main studies including:(1) The characteristics, main types and propagation rules of seismic wave field with typical near-surface theoretical models are analyzed and studied by means of two dimensional acoustic wave equation combined with ray-tracing based eikonal equation finite-difference wave front simulation, also by means of seismic wave field snapshots and shot records. This has provided reliable referenced proofs for seismic data acquisition, processing and interpretation in the complicated near-surface area.(2) An effective measure to express the seismic wave energy propagation that is derived from the theory of seismic wave energy is brought forward. Using the energy source of continuous harmonic wave and by means of numerical simulation of elastic wave equation, the divergency field, curl field, kinetic energy field and potential energy flow field of elastic waves are obtained and be used to describe the energy and propagation characteristics of elastic waves quantitatively. Specially, we studied the energy field and propagation features of seismic waves with complicated near-surface and complex structure models.(3) Start form the theory of seismic wave energy, the calculation method of illumination intensity of wave-equation is educed. The methods of directional decomposition and the intensity calculation of beamed illumination of seismic wave field are brought forward, based on the Poynting Vector.(4) Proceed from the propagation and imaging theories of seismic waves, the calculation method of point spread function (or resolution function) of wave equation is obtained. We also studied the key factors that affecting the point spread function and this has provided new evaluation measures for the estimation of seismic acquisition parameters.(5) We bring forward an optimized designing method of seismic geometry based on the target-oriented image quality. The preliminary optimized acquisition parameters are estimated based on the geology-velocity model and using the synthetical study of target-oriented seismic wave illumination analysis, resolution analysis, snapshot, shot record and the divergency field, curl field, kinetic energy field, potential energy flow field of elastic waves. Then these preliminary estimated parameters are employed to do the numerical emulating recording along the entire model. Next these emulated shot records are processed using adequate processing steps such as CRP stacking, pre-stack depth migration and so on. Finally by the comparison of geological model and all migrated seismic images, analysis of the image resolution, signal to noise ratio and the structural form, by synthetical analyzed result of all these factors then we can decide if it's necessary to further modify the acquisition parameters. After a few steps of iteration and modification, finally we can get the optimized acquisition parameters to this model that can ensure image quality with cost effectively. Through the practical application to the complicated fault structure models in Jizhong region, the correctness and practicability of this method is validated.