Partial angle domain anisotropy offset method based on TTI medium four-order travel-time equation

Abstract

The invention discloses a partial angle domain anisotropy offset method based on a TTI medium four-order travel-time equation. The method comprises the steps that a TTI medium four-order time difference term is introduced in step-out time analysis, simplification is carried out with the help of horizontal reflector hypothesis of pre-stack time offset, and a concise travel-time inversion equation is further given out for achieving anisotropy parameter estimation; on this basis, common offset distance domain earthquake offset is expanded to a partial angle domain offset system, accurate description on seismic wave rays is achieved, and a fracture prediction level is improved. The method essentially improves the level of the anisotropy offset technology, more accurate and quantitative extraction and description on anisotropy characteristics (such as speed and amplitude) are achieved, fracture detection can be served better, and fracture inversion quality and accuracy can be improved. Azimuth information of seismic data can be fully utilized, sampling on azimuth is sufficient, the credibility of finally obtained information is improved, and the method is less influenced by noise.

Description

technical field [0001] The present invention relates to the field of petroleum exploration, in particular to a local angle-domain anisotropic migration method based on the fourth-order traveltime equation of TTI (Tilted Transverse Isotropy with a Tilted axis of symmetry, referred to as TTI) medium, It mainly serves for high-precision crack detection and analysis. Background technique [0002] Affected by factors such as heterogeneity and anisotropy, the normal moveout in seismic data processing usually changes with the observation azimuth (Normal Moveout versus azimuth, NMOz for short). The research and utilization of the NMOz phenomenon originated in the 1990s At the beginning, it has become an important basis in the anisotropy research system and has been widely used in many research branches. Affected by factors such as the heterogeneity and anisotropy characteristics of the underground medium, the normal time difference of seismic data processing usually shows the chara...

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Problems solved by technology

On the other hand, during the propagation of seismic waves in the underground medium, they have to experience complex distortion and deflection effects, so that the rays reaching the ground cannot usually be approximated by the seismic rays excited and received on the ground

If the observed offset and azimuth of the surface are used to replace the real incident angle and azimuth of the received seismic wave in the underground medium, it will inevitably cause serious errors, which will mislead the subsequent interpretation and evaluation work.

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