Method for time migration of inclined-shaft three-dimensional vertical seismic profile (VSP)

Abstract

The invention discloses a method for time migration of an inclined-shaft three-dimensional vertical seismic profile (VSP). The method includes: gridding an imaging area, and acquiring trajectories of an inclined shaft according to coordinates of demodulator points; extracting root-mean-square velocity from a root-mean-square velocity model obtained from ground data along the trajectories of the inclined shaft; moving the root-mean-square velocity to a time migration imaging datum plane of the VSP to acquire a root-mean-square velocity body; calculating aperture of time migration of VSP data by a formula that migration aperture equals to target layer depth is multiplied by the square of sine with the largest imaging angle and added with a half of the largest wellhead distance; acquiring total travel time of corresponding paths of seismic waves by the aid of a double-square-root equation; extending single-path VSP wave fields to the depth where a borehole geophone is located and completing pre-stack time migration of the VSP data. More reasonable structural imaging of the time migration of the three-dimensional VSP can be acquired through three-dimensional velocity space changing trend and distribution in the shaft trajectory direction and denoted by the inclined shaft, calculating efficiency is high, and simpleness in the process is achieved.

Description

technical field [0001] The invention relates to petroleum geophysical prospecting and seismic prospecting technology, in particular to a method for time migration of a three-dimensional vertical seismic section of an inclined well using the root mean square velocity obtained from surface data. technical background [0002] Seismic exploration is a method of artificially stimulating seismic waves to find underground minerals. By artificially exciting seismic waves, using recording equipment on the surface or underground to obtain data that changes with the propagation of seismic waves in a corresponding observation manner. The process of using surface seismic source excitation and using receivers to record seismic signals at different depths underground to obtain underground information near the wellbore is called vertical seismic profiling (VSP) exploration technology. Using the data obtained in the above-mentioned manner, through normal data processing, an image of the und...

AI Technical Summary

Problems solved by technology

This method iteratively improves the accuracy of the velocity model and improves the imaging quality, but the calculation is large and the efficiency is low.

[0004] The correct velocity model can be obtained by using the well information, but when the velocity changes in space, the velocity model obtained from the well information represents the one-dimensional change of velocity, which is limited in describing the spatial distribution of velocity

Images