Using Sand And Mud Interbeded Model To Test Seismic Vertical Resolution

In seismic prospecting, there are many definitions to describe seismic vertical resolution. Among these definitions, it is the "criterion of Rayleigh" that is applied most widely. But in practice, when the seismologists use the criterion in determining the thickness of thin bed, they find the results usually depart from the real thickness. Thinking of this phenomenon, author finds that the study object of "criterion of Rayleigh" departing from the real medium underground is the key point, and the criterion should be reconsidered. Therefore, author decides to use a newway-construct sand and mud interbed model to study the seismic verticalresolution.First of all, the study refers to a sand and mud interbed model in a monograph named The Way to Obtain a Better Resolution in Seismic Prospecting written by academician Li Qingzhong, then on the basis of quanlitative analysis of the referenced model, author designs a series of model experiments to do quantitative analysis. The quantitative analysis mainly depend on: Firstly, normalized cross-correlationcoefficient-used to describe the similar degree between integrated seismic tracesand model; Secondly, direct comparison between integrated seismic trace and model trace-used to analyze the accuracy of sand bed prediction.Through qualitative and quantitative analysis, author considers that in the case of sand and mud interbed, the impendence trace can approximately predict sand with thickness equalling to ?8; and the impendence traces also can predict sand with thickness equal to or beyond A. /4 more precisely, but, since the thickness and combination of sand and mud interbed are mutative and complex, and the efficient frequency band of seismic section is always limited, so due to the efficient frequency band is not wide enough, , the impendence traces can not predict the true thickness precisely by one hundred percent. Therefore this article come to conclusion: Firstly, the efficient frequency band must be wide enough if youwant to do a precise prediction of sand and mud interbed underground; Secondly, author confirms that the definition of seismic vertical resolution had better use A /8 instead of A /4, and in some special times, vertical resolution even can reach A /10.Furthermore, in allusion to a popular new method of thin bed prospecting abroad-frequency decomposition, the author also does sand and mud interbeded model experiments to test.Finally, the author hopes that these scientific research can do favor to geophysical prospecting.