Research Of Relations Between Shot Density And Receiver Density Of 3D Geometry

In the process of modern oil-gas exploration,acquisition of seismic data is the foundation of data processing and interpretation.And in course of seismic data acquisition,the design of 3D geometry has direct influence on the imaging quality of subsurface geological structure afterwards.But along with the high precision seismic data derived from 3D seismic exploration technology,is the sharply increased exploration costs.According to statistics,the expense of data acquisition in 3D seismic exploration accounts for 80% of the total cost on average.So it has been a recent research focus of estimation and optimization of 3D geometry design to decrease as much the exploration cost as possible,on condition that the quality of 3D seismic data remains the same.Nowadays,the estimation and optimization methods of 3D geometry design mainly include two types: double focusing analysis and CMP element property analysis.double focusing analysis is a estimation method of 3D geometry design based on double focusing theory(Berkhout,1997).Through this method,the shot point imaging amplitude and receiver imaging amplitude of specified target stratum or geological object are obtained by double focusing pre-stack migration imaging,and results are used to estimate the 3D geometry.And CMP element property analysis is mainly applied to optimize the 3D geometry design by analyzing the folds,offset distribution,offset azimuth angle,etc.In this dissertation,based on the double focusing estimation theory of 3D geometry design,plenty of basic parameters are modified to make trace density and shot density change under the premise that shot-trace density remains the same.And by this means,the amplitude of shot point focus imaging,receiver focus imaging,and double focus imaging of specified target stratum are obtained.And then,the theoretical feasibility of modifying the various parameters of 3D geometry to decrease the exploration cost as well as maintaining the quality of seismic data.The modified parameters may include receiver inverse,shot inverse,receiver line inverse,shot line inverse,etc.In addition,the minimum signal a seismic geophone can receive as well as the sensitivity of it is analyzed to confirm the maximum offset of a 3D geometry.And the uniformity of offset distribution is quantitatively evaluated based on the coefficient of correlation of element offset uniformity,combined with the double focus imaging results.In this final part,the influence of variation of offset uniformity on imaging quality is analyzed on condition that basic parameters of 3D geometry are modified.