Abstract:

The Lianglitage Formation, being the high quality reservoir, has always been the important target in the researches for exploration in Tazhong area. However, researches on the sedimentary characteristics of the northwestern part in the northern slope of Tazhong area (Tazhong 85-49 well) still inadequate. Based on cores, thin-sections, well-logging data and seismic data, the Lianglitage Formation is divided into 3 third-order sequences, 5 systems tracts and 9 to 15 fourth-order sequences, and the high-resolution sequence stratigraphy framework is established in the research area. 8 microfacies are identified in research area and according to their specific combination, 4 sedimentary facies are recognized in fourth-order sequence, including reef complex, medium-high energy grain bank, medium-low-energy grain bank and lagoons-sea. Distributional characteristics of sedimentary facies is studied, based on the foundation of high-resolution sequence stratigraphy and sedimentary characteristics, focusing on the analysis of the facies evolution pattern in cross-section of HST and TST in SQ1 and SQ2 and contrast of facies distributions in flat between different periods. As a result, the evolution pattern of sedimentary facies is revealed, which benefits the further guidance of the oil and gas exploration of research area in the future.

Key words: high-resolution sequence stratigraphic framework, microfacies, facies sequence, Lianglitage Formation, western Tazhzong