Method for quick switching wave direct simulation to determine formation lithology and lithofacies change

Abstract

The invention relates to a method for realizing the rapid direct simulation of converted wave post-stack seismic records so as to determine the changes of formation lithology and petrographic facies; the steps are as follows: when the longitudinal wave speed and the transverse wave speed are utilized for obtaining the two-way vertical travel, logging information in a depth domain is converted into a P-SV wave time domain; the uniform re-sampling is carried out to the logging information which is irregularly sampled in the time domain, thereby determining the P-SV converted wave reflection coefficient on each new sampling point; the convolution is carried out to the obtained P-SV converted wave reflection coefficient and seismic wavelet according to the conventional longitudinal wave processing method, thereby obtaining the simulated seismic records of the P-SV converted waves; the related processing is carried out the simulated result and the actual post-stack seismic records according to the conventional longitudinal wave processing method, thereby realizing the horizontal calibration of the P-SV converted waves and determining the changes of the formation lithology and the petrographic facies. The method does not need the ray tracing and the calculation of incident angles and transmission angles or the filtering treatment of logging curves, thereby improving the calculation efficiency of the simulation of the post-stack seismic records and being capable of reflecting the high-frequency response characteristics of the logging information.

Description

technical field [0001] The present invention relates to the processing technology of petroleum geophysical exploration seismic data, which is a method for fast and direct simulation of converted wave (downgoing longitudinal wave, upgoing shear wave, namely P-SV wave) post-stack seismic records to determine stratum lithology and lithofacies changes method. Background technique [0002] Seismic exploration is to artificially excite and generate seismic waves on the surface, use single-component or multi-component sensors to record the formation response of seismic waves on the surface or underground, and study their propagation laws in the formation to find out the underground geological structure and lithology changes. Geophysical prospecting methods for oil and gas fields. [0003] For a long time, seismic exploration has used a single longitudinal wave for exploration. As the degree of oil and gas exploration increases, the difficulty of exploration is also increasing. Co...

AI Technical Summary

Problems solved by technology

[0017] From the implementation process of this method, it can be seen that: firstly, when using formula (2) to calculate the reflection coefficient, the incident angle, reflection angle and transmission angle of the longitudinal and shear waves must be calculated by ray tracing; High-frequency response, the reflection angle and transmission angle obtained in the ray tracing process are likely to change drastically, and even often reach or exceed the critical angle, which cannot satisfy the premise assumption of (2) approximation (the incident angle is small and cannot reach the critical angle ), therefore, in practical applications, not only the log curve needs to be smoothed, but also the angle range in the simulation process is required to be relatively small; in addition, the complex ray tracing process itself reduces the computational efficiency of the converted wave simulation

Images