Analysis of high-resolution sequence stratigraphy of the Upper Jurassic Penglaizhen Formation in the Baimamiao gas field, Qionglai County, Western Sichuan

Abstract：Under the guidance of the theory and techniques of high-resolution sequence stratigraphy, through a comprehensive analysis of the outcrops, rock cores, well logs and seismic data, 3 sequence boundaries of different genetic types and growth scaleｓ and 3 orders of lacustrine flooding surfaces are recognized in the Upper Jurassic Penglaizhen Formation in ｔｈｅ Baimamiao gas field, and in addition, 2 long-term base-level cycles, 6 middle-term base-level cycles and 38-40 short-term base-level cycles are distinguished and their characteristics are discussed in detail. The thin-bedded limestone and calcareous shale close to the top of the middle-term base-level cycle can be regarded as one of the important indicator for recognizing the middle-term base-level cycle. On the basis of the above, using the method of cycle isochronostratigraphic correlation, different orders of base-level cycles are correlated and 3 isochronostratigraphic stratigraphic frameworks with different time-scales are established. The high-resolution sequence stratigraphic analysis has great significance for further exploration and development of the gas accumulations in the Penglaizhen Formation of the Baimamiao gas field.