# Discussions on the Processing of the Multi-Component Seismic Vector Field
## 1 Introduction  
The three-component seismic data in a three-dimensional Descartes system simultaneously record the linear motion of the particle in the vertical and horizontal directions as well as retain a relatively complete record of seismic wave translations. They not only simultaneously provide the travel time (velocity), amplitude, and frequency information of the compressional (P) and shear (S) waves but also provide the relative amplitude relationship of the same wave among different components, as well as the amplitude, frequency, phase, and travel time differences for different waves. The information of these vector wavefields would provide a more detailed and accurate characterization of the structure, lithology, fluid saturation, pore pressure, and fractures of an underground medium [1]; however, because of the limitations of current methods and processing techniques of seismic data, such information cannot be fully obtained. The advantages of the current multi-wave and multi-component seismic techniques are limited to the following [2; 3; 4; 5]: (1) inversions of travelling time and waveform for the P-wave only [6; 7]; (2) shear-wave birefringence analysis [8]; (3) compensation of a defect caused by the difficulty of imaging with a PP-wave under a gas cloud, a salt dune, or in a low-acoustic impedance area using PS-wave imaging [9; 10]; (4) anisotropy and fracture identification [11]; and (5) prediction of reservoir lithology and fluids [12]. In particular, except for the prediction of the fast and slowshear polarization and the fracture azimuth that uses the vector field information of the S-wave, other methods and applications only use the scalar wavefield information of the P-wave and S-wave. If we were able to fully use the vector field information of the P-wave and S-wave, we would be able to more accurately estimate the anisotropic parameters [13], quantitatively describe the parameters of fractures and pores, and finely depict the reservoir lithology, or even directly identify oil and gas reservoirs. [PERSON] et al. provided a very detailed discussion of the significance of studies on the geophysical vector field [14]. The prerequisite for making the best use of the vector information of a seismic wavefield is that the processing of the seismic data must retain the vector characteristics of the wavefield. Even the ordinary processing of amplitude compensation and de-noising should be performed very carefully; the original scalar field method cannot simply be adopted [15; 16] to independently process each component. Otherwise, the processing is prone to interrupt the relative amplitude relationship of the vector data and cause mistakes in subsequent applications of the vector information. Therefore, the processing system of multi-wave and multi-component seismic data not only should be a simple expansion of a single-component processing system of the P-wave but also should possess a set of processing methods and procedures that are specifically suitable for the multi-component vector field. So far, some studies have treated the multi-component seismic data as a vector field. For example, [PERSON] et al. [17] and [PERSON] et al. [18] applied the full-waveform inversion of a multi-component seismic elastic wave to estimate the elastic parameters of the shear modulus, Lame constant, and anisotropy. The vector wavefield separation method proposed by [PERSON] et al. [19] and [PERSON] et al. [20] can retain the vector form of the P-wave and S-wave data after their separation with no distortion in the amplitude and phase. The reverse time migration imaging technology of the elastic wave proposed by [PERSON] et al. [21] and [PERSON] et al. [22] directly used the vector field as the input. However, these vector processing techniques are still in the initial stages of research, and they are only sporadically distributed on a small number of independent links of the processing procedure for multi-component seismic data.