Method and system for correcting root mean square velocity of sound wave by using vsp velocity

Abstract

The invention provides a method and system for correcting the root mean square velocity of a sound wave by utilizing a VSP velocity. The method comprises the steps that S1) a borehole environment influence of a sound wave time difference curve is corrected, and then sound wave time difference is converted into a sound wave layer velocity; S2) depth-time conversion is carried out on the sound wave layer velocity to obtain a sound wave layer velocity in the time domain, the sound-wave root mean square velocity Vrms<L> is calculated, and the VSP root mean square velocity Vrms<V> is calculated; S3) an error deltavrms(ti) between the sound-wave root mean square velocity and the VSP root mean square velocity in each time point is calculated; S4) a polynomial f(t)=a0+a1t+a2t2+...+antn is designed, so that the polynomial matches a deltavrms(ti) optimally, and coefficients a0, a1, a2...an are determined; and S5) a corrected sound-wave root mean square velocity Vrms<Lc>(Ti) is calculated. According to the invention, the pickup randomness is reduced, and the precision of the root mean square velocity is improved.

Description

Technical field [0001] The invention relates to the field of acoustic wave logging processing, and in particular to a method and system for correcting acoustic wave root-mean-square velocity by using VSP velocity. Background technique [0002] As we all know, due to the different excitation sources of sonic logging and seismic exploration, and the different receiving methods, for the same formation, the velocity (root mean square velocity and layer velocity) obtained by sonic logging is different from the velocity value obtained by seismic data velocity analysis. Therefore, the sonic logging velocity cannot be directly applied to seismic data velocity analysis and must be corrected. [0003] The root mean square velocity is the velocity picked up by the seismic velocity spectrum. From it, the layer velocity of the strata is converted through the DIX formula. The layer velocity model is established and applied to the pre-stack depth migration processing of seismic data. Therefore, t...

AI Technical Summary

Problems solved by technology

Because the velocity obtained by VSP (Vetical Seismic Profile, vertical seismic profile) logging is not only accurate, but also equivalent to the velocity value obtained by surface seismic, it is a pity that the number of VSP logging is small and the data is limited, while the number of acoustic logging is large and the data Therefore, at present, most researchers use VSP layer velocity to correct the layer velocity of acoustic logging, but the implementation method is cumbersome and needs to be carried out in layers.

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