Characteristics And Distribution Of Carboniferous-Permian Strata In Linqing Depression

This paper has a preliminary study on lithologic characteristics of 14 bore wells which encountered Palaeozoic in the eastern area of Linqing Depression, utilizes the method of integrative stratigraphy, synthesizes lithostratigraphy,biostratigraphy,logged-stratigraphy and seismic stratigraphy, then summarizes Carboniferous-Permian formation characteristics of the study area. Combining predecessors' study results on Carboniferous-Permian boundary, it suggests that the Carboniferous-Permian boundary in the study area lies at the bottom of Streptognathodus elongates-S.wabaunsensis-S.gracilis Assemblage Zone in Taiyuan Formation, being approximately amount to the bottom of Pseudoschwagerina Fusulinida Zone; at the same time, it summarizes the important marker beds which are the basis of dividing and comparing strata in the study area. Biogenetic derivation sequences, logged and seismic documents are helpful to identify the marker beds, and combined stratigraphic methods are used to demarcate lithologic, biogenetic derivation characteristics of single bore well; then from dividing strata to comparing strata among several wells, with the help of seismic and geophysics methods, we compare lithologic characteristics of several well to demarcate seismic profiles, and monitor strata distribution in line, get the bar diagram of comparing strata; after that, we establish the distribution of Benxi, Taiyuan, Shanxi, Lower and Upper Shihezi Formation in cover of Linqing Depression, get thickness maps of relic; based on these and incorporated the statistic data of drill cores, we map thickness distribution graph of coal and dark mudstone in the eastern area of Linqing Depression; it is concluded that there are two depocenters in Carboniferous-Permian in the study area, selectively situated in the northeast of Dezhou sunken and the center of Gaotang-Tangyi bulge; the depocenter of hydrocarbon source rock such as coal and dark mudstone is situated in the Xinxian sunken in the south of the study area; the depocenter of two important reservoir beds (Lower and Upper Shihezi Formation) is situated in the Gaotang-Tangyi bulge in the center of the study area.