Abstract: In recent years, a number of wells in central Sichuan have drilled high-yield industrial airflow in Qixia Formation, showing the great exploration potential of the strata. However, compared with the northwestern margin of Sichuan, the carbonate beach body of Qixia Formation in Longnvsi Area is smaller in scale and thinner in reservoir thickness, which is far lower than the seismic longitudinal resolution, and has not achieved good reservoir prediction effect, which seriously restricts the oil and gas exploration and development in the vast area of the platform. Therefore, in view of the difficulty in thin reservoir prediction in the platform, the reservoir control factors and prediction geological model of Qixia Formation in Longnvsi Area of central Sichuan are studied by comprehensively utilizing core and thin section, combined with logging and seismic data, and the idea of close combination of geology and geophysics. The results show that the reservoir of Qixia Formation in this area is mainly beach dolomite reservoir, and the reservoir rocks are mainly grain dolomite and dolomitic limestone. The main reservoir space is intergranular (dissolved) pores and caves, and a small amount of cracks are visible. The main factors controlling the formation of relatively high-quality reservoirs in Qixia Formation are the position of paleogeomorphology, sedimentary microfacies and fracture development in Qixia Period. Based on this, a thin reservoir prediction geological model of Longnvsi Qixia Formation in “Qixia Period paleogeomorphology highland+ shoal core and Shoal margin microfacies+fracture development area” is established, and on this basis, the favorable areas for reservoir development are optimized. The research results provide important support for the optimization of favorable zones for oil and gas exploration deployment in the platform of Qixia Formation.

Key words: Longnvsi Area, Qixia Formation, thin reservoir prediction, geologic model, shoal