Time-domain seismic interval velocity inversion method

Abstract

The invention provides a time-domain seismic interval velocity inversion method, and belongs to the field of seismic exploration data processing. The time-domain seismic interval velocity inversion method includes acquiring initial instantaneous velocities by means of seismic logging; establishing relations among the instantaneous velocities and root-mean-square velocities; converting the initial instantaneous velocities into root-mean-square velocities; constraining actually picked root-mean-square velocities to create an objective function; solving the objective function to obtain variables required for updating a velocity model; acquiring a final interval velocity when a value of the objective function is smaller than a threshold value epsilon after repeated iteration. The time-domain seismic interval velocity inversion method has the advantages that the stable velocity can be acquired by the time-domain seismic interval velocity inversion method, the stable and smooth interval velocity model can be provided for migration, the velocity can be used for seismic migration imaging, and data support can be provided for oilfield development and petroleum drilling.

Description

Technical field [0001] The invention belongs to the field of seismic exploration data processing, and specifically relates to a time-domain seismic layer velocity inversion method. Background technique [0002] Dix proposes a formula for estimating layer velocity from root mean square velocity: [0003] V 0 , n = V 2 , n 2 t n - V 2 , n - 1 2 t n - 1 t n - t n - 1 [0004] Where V 0，n Is the layer velocity, V 2，n-1 , V 2，n Is t n-1 Root mean square velocity of the upper and lower interfaces at the moment, t n For the corresponding travel time. According to this formula, even when the root-mean-square velocity changes very little, it is easy to cause negative velocity without physical meaning and large instability of velocity value. The accuracy of layer velocity estimation is critical for both time and depth migration. Therefore, many scholars have devoted themselves to studying the co...

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Problems solved by technology

The Harlan algorithm sets a set of velocity functions and uses the least square method to find the global solution. This method first filters the velocity singularities to avoid excessive changes in the velocity calculation process of the layer velocity. However, this method directly removes the so-called bad speed point, there is no physical basis for this practice

[0005] The Dix formula inversion calculation layer velocity model is prone to produce negative velocities that have no physical meaning, resulting in drastic changes in the velocity field. This velocity field does not meet the requirements of the migration for the velocity model.

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