Известия Томского политехнического университета: Инжиниринг георесурсов (Sep 2017)
Definition of temporary shift between seismic traces on the basis of the analysis of their phase-frequency characteristics
Abstract
The relevance of the study. The procedures for determining temporary shift, which are widely spread in practice, do not always guarantee the accuracy in defining static corrections. The arising errors lead to a distortion of kinematic parameters of the reflected waves. This affects adversely all subsequent constructions. Therefore, development of the effective method for determining the temporary shift is the relevant issue. The prospects of increasing the reliability of designing the structures, prepared for oil and gas exploration, are related to the successful solution of the problem. The aim of the study is to develop and explore the reliability of the algorithm for determining the temporary shifts between seismic traces based on the optimal and suboptimal processing of phase-frequency characteristics of the reflected waves recorded when searching for oil and gas fields. The methods used in the study: statistical synthesis and analysis of optimal decision rules, digital signal processing, methods of discrete Fourier transform, mathematical modeling and computer experiment. The results. The authors showed the possibility of extracting useful information from the phase-frequency characteristics of seismic signals for obtaining the effective estimates of temporary shifts between traces. Based on the theory of statistical solutions the optimal algorithm for determining the temporary shifts by the instantaneous mutual phase spectra was built. For practical implementation of the algorithm, the authors proposed a transition from optimal to suboptimal processing of the components of the instantaneous mutual phase spectra by summing the equilibrium. It is shown that the equilibrium processing leads to almost twice reduction of the total signal/noise ratio for practically used strip of frequency. Even such losses allowed obtaining rather reliable estimates of temporary shifts at the intense irregular interference and symmetric distributions of temporary shifts with large dispersion.
