**4. Real Data Application**

### *4.1. Data Characteristics*

Figure 4 shows a single-shot record of the P-wave source in the study area; theoretically, the seismic records generated by P wave sources do not have shear wave fields. As shown in Figure 4a, with the X-component wave field seismic record of the P-wave source, the wave field is relatively complex, the converted wave signal is relatively weak and submerged in a large amount of scattering noise, and there is obvious leaked pure shear wave information in the near trace. The Y-component wave field seismic record is shown in Figure 4b; there is basically no converted wave information in this component, and the near trace is dominated by noise with weak pure shear wave information. The Z-component wave field seismic record is shown in Figure 4c; the P-wave reflection hyperbola characteristics of the shallow part are relatively obvious in this wave field, the near-trace is dominated by noise without pure shear wave information, and the deep information is submerged in a large amount of scattered noise. The reason why the converted wave signal of the P-wave field is relatively weak and the effective information of the wave field is submerged in a large amount of

scattered noise is likely due to the fact that the area is a biogas enrichment area in relatively deep strata based on the geological characteristics of the area, which is also the reason why the use of P-wave data for reverse time migration imaging in this area is not ideal.

**Figure 4.** (**a**) The X-component wave field seismic record of the P-wave source. (**b**) The Y-component wave field seismic record of the P-wave source. (**c**) The Z-component wave field seismic record of the P-wave source.

Figure 5 shows the corresponding single-shot record obtained from the SH shear wave source (i.e., the y-direction concentrated force source) in this area. As shown in Figure 5a, the X-component data, there should be no SH shear wave information in isotropic media, but there is relatively weak SH shear wave signal leakage in actual data. The most likely cause of SH shear wave signal leakage is due to shear-wave splitting, which is not the focus of this article. The seismic record of the Z-component wave field in Figure 5c is dominated by noise without SH shear wave information, which is consistent with the theory of the SH shear wave propagation. In theory, the wave field obtained by concentrating force sources in the y-direction only has wave field information in the Y-component in isotropic media. Figure 5b is the seismic record of the y-component wave field, with a high signal-to-noise ratio and obvious SH shear wave information. Overall, the resolution of SH shear wave seismic records is higher than that of P-wave seismic record, comparing Figure 5b with Figure 4c. SH shear wave source data can also have a high signal-to-noise ratio in the deep gas cloud region due to its insensitivity to gas, and it has great advantages in geological structure characterization and reverse time migration imaging research in this area.

**Figure 5.** (**a**) The X-component wave field seismic record of the SH shear wave source. (**b**) The Y-component wave field seismic record of the SH shear wave source. (**c**) The Z-component wave field seismic record of the SH shear wave source.

It can be seen through the analysis of shot records that the data quality of the SH-Y component is relatively good. This research focuses on imaging research on SH-Y component data. This component is perpendicular to the survey line direction.
