Research and application of the joint surface modeling in the huge-thick loess area in southwest Tarim

The piedmont zone in the southwest of Tarim Continental Basin is mainly covered by huge-thick loose loess, up to 500m in thickness with a gravel layer at the bottom. It is high-velocity anomalies partially under the gravel layer, where the surface structure changes drastically in the longitudinal and transverse velocity, resulting in low S/N ratio so that an accurate near-surface model is difficult to be built. The accuracy of seismic imaging needs to be improved urgently. To achieve accurate seismic imaging, a field and indoor joint surface modeling research is made. The surface relate basic data are obtained through deep uphole and reflection survey in the filed; while the surface modeling of model constraint, refraction and tomographic joint inversion is studied indoor. After the above technical measures are taken, the near-surface structure in the complex surface area is dissected for the first time in a local fine manner. Compared with the conventional surface modeling, this technology improves the accuracy of near-surface model and the seismic imaging effect effectively.