Well-control-free longitudinal and transverse wave velocity ratio inversion method

Abstract

The invention discloses a well-control-free longitudinal and transverse wave velocity ratio inversion method. The method comprises the steps: acquiring attributes, sensitive to reservoir lithology andphysical properties, of a to-be-inverted region by using geological data, pre-stack time migration seismic data and well logging data; optimizing a seismic pre-stack gather generated by the pre-stacktime migration; extracting three input wavelets of pre-stack synchronous inversion from pre-stack time migration seismic data; carrying out pre-stack depth migration processing on the pre-stack timemigration seismic data to obtain a longitudinal wave velocity model; with a distribution range of the density and the longitudinal and transverse wave velocity ratio as a constraint condition, calculating a density model and a transverse wave velocity model; and calculating a longitudinal wave impedance model and a transverse wave impedance model based on longitudinal and transverse wave impedancemodel calculation formulas; and with the longitudinal wave impedance model, the transverse wave impedance model and the density model as inversion inputs, setting an inversion iteration frequency tocarry out inversion to obtain an inversion result. Therefore, the precision of the inversion model and the accuracy of the inversion result of the well-free area low-frequency range are improved.

Description

technical field [0001] The invention relates to the technical field of petroleum geophysical exploration, and more specifically, relates to a method for inversion of the velocity ratio of compressional and shear waves without well control. Background technique [0002] The P-to-S wave velocity ratio information of the formation has a good effect on identifying the reservoir, and is generally obtained through pre-stack synchronous inversion. Seismic gather quality, low-frequency model, and inversion parameter setting are the three key factors affecting the inversion accuracy of P-wave velocity ratio. The low-frequency model is generally affected by the number of wells and their distribution. When the number of wells is large and the wells are evenly distributed on the plane of the work area, the low-frequency model is generally more accurate. When there are no wells or few wells in the work area, the accuracy of the low-frequency model is low or even difficult to establish, ...

AI Technical Summary

Problems solved by technology

[0004] The present invention provides a P / S wave velocity ratio inversion method without well control in order to overcome the disadvantages of poor accuracy of the low-frequency range inversion model and unsatisfactory inversion results in the prior art without wells

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