Characterization of thin deltaic sand bodies of Carboniferous Karashayi Formation in Tahe Oil Field

The Carboniferous Karashayi Formation in the Tahe Oil Field has a large burial depth, thin sand body thickness and fast lateral changes. Conventional wave impedance cannot easily distinguish sand and mudstone, and it is difficult to characterize sand bodies, which restricts the exploration and development in this area. Under the constraints of a sand body geological model, the combination of seismic waveform inversion and stratigraphic slice analysis was used to describe the sand bodies. The seismic waveform inversion technology can improve the vertical and horizontal identification accuracy of sand bodies synchronously, and realize the prediction of thin sand layers more than 3 m thick in the Karashayi Formation of the study area. The inversion results are highly matched with wells, and the post-test well-matching rate is 88.1%, which effectively improves the recognition ability of thin sand bodies. Stratigraphic slice analysis of the variation characteristics of the sand bodies in the target interval better reflect the sedimentary evolution of transgression and regression in the study area, and characterize the plane distribution of the thin sand bodies in the delta, providing a geological basis for finding favorable sand body development zones.