Mountain surface velocity model building method and mountain surface velocity model building system

Abstract

The invention discloses a mountain surface velocity model building method. The method comprises the following steps: building an observation system according to earthquake data, and obtaining a firstbreak travel time and offset curve of each shot-receiver pair according to first break time picking of the earthquake data; obtaining common midpoint floating datum plane through calculation based onelevation of the shot point and a detection point in a common midpoint predetermined range, and performing floating plane correction for each shot point and detection point according to the common midpoint floating datum plane; according to the corrected shot point and detection point and a value of the first break travel time and offset relation curve, obtaining an actually measured travel time-offset curve through calculation; solving a Herglotz-Wiechert formula through a Simpson integral method for predetermined amount of offset according to the actually measured travel time-offset curve, and obtaining rotating point depth of a rotating wave corresponding to the offset; and obtaining a one-dimensional velocity-depth function of a predetermined common midpoint position through calculation according to the rotating point depth, and building a near-surface velocity model according to the one-dimensional velocity-depth function.

Description

technical field [0001] The invention relates to a seismic data processing technology for petroleum geophysical exploration, in particular to a method and system for constructing a mountain surface velocity model. Background technique [0002] The subsurface formations near the surface are called regoliths and are usually thin layers of low-velocity, uncompacted material. For petroleum exploration, the near surface can be assumed in most cases as a structure whose velocity increases with depth. It is well known that to obtain accurate imaging of deep subsurface formations and reservoirs, the effects of near-surface anomalies on seismic reflection data must be removed. In addition, the near surface is also an important and challenging object in velocity field modeling for prestack depth migration. The first arrival time contains information related to near-surface velocity. The traditional method of removing the effects of regolith is various refraction statics. [0003] T...

AI Technical Summary

Problems solved by technology

Therefore, shot-based methods are actually averaged over the length of an array range, which does not have sufficient resolution in complex subsurface geology

In addition, the horizontal resolution of the inversion results of shot set data depends on the spacing of shot points, which sometimes appears sparse

In summary, for mountainous seismic exploration, the terrain is undulating, and the Herglotz-Wiechert formula cannot be used directly to invert the near-surface velocity model

Images