Abstract: To find the "sweetness" in the deep tight sand and reduce the prediction error of the thickness of the high-quality reservoir is the key factor to promote the exploration of gas-containing structure evaluation and the upgrading of reserves in the Y work area. Using three-dimensional seismic data of the wide bandwidth and wide azimuth of the Y work area, combining with the results of simultaneous inversion, the boundary of the deep reservoir and the longitudinal and transverse unevenness are finely identified and characterized, and then the "sweetness" in the deep tight sand layer is identified. The results show that the identification results of the "sweetness" are consistent with the actual logging well, which provide a basis for the upgrading of the reserves of the Y structure.