Study on Sequence Stratigraphy and Sedimentary Facies of the Upper Permian Leping Formation in the Junlian Area
Junlian area in southern Sichuan has a large reserve of coalbed methane resources in the Leping Formation,and the overall exploration level is relatively low,which restricts the extraction of coal and coalbed methane resources.The accumulation of coal seams and the distribution of sandstone reservoirs are controlled by sedimentary facies and sequence stratigraphic framework.To explore the development characteristics of coal seams and the sedimentary control factors of coal seam accumulation in the research area,on the basis of drilling and core data,using the principle of Sequence stratigraphy,the third-order sequence boundary developed in the Leping Formation in the area is identified and the sequence is divided to build the sequence stratigraphic framework;Clarify the names of coal bearing strata in the research area;Using lithofacies markers and logging response characteristics for stratigraphic correlation,single well sedimentary facies division,and well connected sedimentary facies comparison,to clarify the development characteristics of sedimentary facies within each sequence.The results indicate that there are four sequence boundaries in the Leping Formation of the study area,and three third-order sequences are divided based on these four sequence boundaries.Based on the logging response characteristics,two types of sedimentary facies,five types of sedimentary subfacies,and nine types of sedimentary microfacies were identified.The first sequence(SQ1)and second sequence(SQ2)mainly develop fluvial facies,while the third sequence(SQ3)develops tidal flat facies.On the profile,the overall manifestation is the evolution characteristics from river facies to tidal flat facies;The evolution trend from west to east is reflected in the river tidal flat lagoon facies.
万方数据
维普
