Analysis Of High Resolution Sequence Stratigraphy And Sedimentary System Of Dongying Formation In The Jiazhangsi Area, Liaohe Basin

This paper discusses the feature of Dongying group's sequence stratigraphy andsedimentary system of Jiazhangsi area by analyzing large mount of materials such asloging data ,seismic data and rocks core. There are three third sequences and thirteenforth-order sequence. The top boundary of Sequence I(SqI) is an unconformity surfacewhich is the boundary of Guantao group and Dongying group, and there is a set ofcontinuous volcanic rock.. The bottom boundary of SqI is a set of siltstone—fine stonewhich thickness is about 5-10 meters and which is a double arces at apparent resistivityloging. The bottom boundary of SqII and SqIII are both a set of continuous volcanicrock..The study about Sq1 show that : the low-stand system tract(LST) are characterizeddelta front subfacies recognized several microfacies ,include underwater distributarychannels, debouch bars and sheet sands. Lake expand system tract(EST) is consisted ofdelta-front sheet sand and interdistributary bays which show finger in logging. High-standsystem tract(HST) are consisted of delta front subfacies and volcanics facies which showsstrong seismic phase and high resistivity loging. The LST of SqII and SqIII are bothconsisted of delta front subfacies and volcanics facies;the EST and HST are consisted ofdelta-front sheet sands and shore shallow lacustrine facies;and there is a set ofcontinuous mud rock between EST and HST , which is most flood surface(mfs).The principal control factors of sequence development of Dongying group includetectonic subsidence, the supplying rate of sediment, climate and the change of relativelake level. Tectontic subsidence and the change of relative lake level are dominantcontrolling factors, which are controlled by fault activity and volcanic activity.The oil-gas reservoir type in this area include lithological reservoir and tectonic-lithological reservoir, which development controlled by sequence, the distribution ofsedimentary system and fault system. Major oil-gas reservoir locate underwaterdistributary channels facies in LST near fault system. And SqIII is the principal targetstrata. The action of volcanic rock is cover coat because of condensation.