Carboniferous-Permian sedimentary facies characteristics and paleoenvironmental reconstruction in northeast Jizhong depression

Carboniferous-Permian strata in Jizhong depression constitute an important gas hydrocarbon source rock in Bohai Gulf Basin,and also serve as an main natural gas exploration area currently in the North China Oilfield.In order to achieve a breakthrough of gas exploration in the study area,the authors studied Carboniferous-Permian depositional systems and depositional paleoenvironment,on the basis of the lithologicelectric logging features,characteristics of sedimentary cycles,paleontological features,core observations and analytical and test data of drill holes,in combination with results of seismic interpretation.It is pointed out that the study area has developed three types of sedimentary systems: tidal flat-swamps,river deltas and river dominated system.The depositional environments can be classified into three types : the epicontinental sedimentary environment of slow subsidence,the paralic depositional environment of slow uplift and the fluvial environment of rapid uplift.