In the"dual complex"area of Xindianzi

Yongchuan

all the reasons that the near surface factors vary greatly

the structure is complex

and the signal-to-noise ratio of data is low make the accurate imaging difficult. During the shale gas exploration and development

there are some problems of Xindianzi such as unclear anticline structure

inaccurate imaging of local small faults

and inconsistency of horizontal well design trajectory with actual drilling. The conventional grid tomography inversion method has poor applicability in velocity modeling of low signal-to-noise ratio area. It is difficult not only to obtain the quasi shallow velocity and eliminate the influence of complex near surface on imaging

but also to realize effective data driving in the middle and deep layers and update the velocity accurately in the middle and deep layers. In order to solve the problem of depth domain modeling in"dual complex"area

full offset first break tomography inversion is used to obtain near surface velocity

then the appropriate interface is selected to fuse the models of shallow and medium depth. In the iterative process of grid tomography

the constraints on velocity by the construction model can realize the corresponding between low-frequency velocity and structural distribution

and get high-frequency convergence. The application results show that the joint application of shallow

medium and deep fusion modeling and structural constraint grid tomography technology make up for the shortcomings of the conventional methods

the resulting final velocity field is more accurate

and the imaging of the"dual complex"area is obviously improved. The results strongly support the exploration and development of this area.