The Research Of Sedimentary Characteristic Of Cretaceous In Three-Dimensional Of Fangzheng Depression

This paper mainly uses the sequence stratigraphy,seismic stratigraphy and sedimentary petrology theory as its basis.According to the seismic,drilling and logging data,identify the sequence boundary of Cretaceous in FangZheng fault depression and divide three order sequences.The ultimate purpose is to establish the high resolution sequence stratigraphy and to divide the Cretaceous into 3 three-order sequences.Based on sequence stratigraphy and seismic stratigraphy,seismic reflection termination recognition on ultrasound,the next super,truncated and incised valley and other seismic phenomenan,identifying the incised valley is mainly distributed in the interface of Cretaceous and the Xinancun + Wuyun formation,which is the unconformity interface for T5,in order to supply reasons to divide sedimentary facies.Through the description of the core observation and combining with the logging,well logging and seismic data analysis,there are three kind of Sedimentary system of Cretaceous in FangZheng fault depression,including fan delta system,lake system and the lake floor fan system.The fan delta facies can be divided into 2 subfacies,which are the fan delta plain and fan-delta front;mid fan facies mainly developments in fan facies.Establishing the sedimentary facise identification mark and analysing the flat facies and profile facies in the sequence stratigraphy framework in order to reveal the sedimentary facies distribution of Cretaceous in FangZheng fault depression.Based on the sequence stratigraphy sedimentary facies distribution characteristics and the study of combination of hydrocarbon generation,reservoir and caprock,sand and oil and gas distribution was discussed.According to the analysis of reservation condition,indicates the favorable exploration zone.Cretaceous top fills poor layer in Fang 402 well,fang 4 well and fang 6 well area.Fan delta front subfacies is favorable reservoir which developed well in Cretaceous in the west of YiHanTong fracture.combined with trap evaluation results,there is not favourable oil and gas zones in Cretaceous.The more favorable area is located in side fang 4 well,fang 6 well and fang 402 well,at the east of Trace 550.