There are large amount of faults in Nanpu depression which is a Cenozoic hydrocarbon rich depression in Bohai Bay Basin,and a large number of pools accumulated around faults.Assemblage styles of fault both in plane and section were analyzed in this paper.Faults of Nanpu depression can be classified into four styles in plane: parallel,interlaced,pectinate,and fastigiated style;three fault assemblages in section including complex "y",flower structure and ladder pattern.According to the analysis of distribution of faults,sand bodies and hydrocarbon reservoirs,it has been found that concave of second to third order growth faults are the principal orientation of oil migration,where thick and high porosity and high permeability reservoirs were obtained.Down-dip block of contrarotation faults and upfaulted block of homodromous faults are the favorable oil accumulation locations.Fault zone can be divided into three parts: up-induction-fracture,middle crush,and down-induction-fracture zone.The up-induction-fracture zone owns higher permeability than down-induction-fracture,so the former is favorable place of oil migration and the latter inclines to be plugged zone.

The sandstone reservoirs in the Chaluhe depression,Yitong Basin,Jilin have moderate to low porosity and low permeability.The types and contents of clay minerals tend to have an important effect on the physical properties of the hydrocarbon reservoirs.The results of SEM and X-ray diffraction analysis have revealed that there is a negative correlation between the absolute contents of clay minerals and their porosity and permeability.The permeability tends to decrease in response to the increase of the contents of illite,and to increase in response to the increase of the contents of kaolinite.The porosity is less variable in response to the relative contents of the clay minerals.

The Caluhe Depression of the Yitong Basin is a extension rift basin,due to the complex tectonics,particular morphology,sedimentary source from several directions,several depocenter and subsidence center and the rapid facies transition,there is much difficulty in the stratigraphic division and correlation.Based on the data of predecessor research,involved some methods and data of well lithology,geophysical,paleontology,combined with sequence stratigraphy,this paper deals with the Eocene stratigraphic division and correlation of the Chaluhe Depression in the Yitong Basin.It is suggest that Eo-cene is made of the Shuangyang Formation,the Shelin Formation and the Yongji Formation,and indicate the evidences of strata division and correlated,and analysis the correlation between the Yitong Basin and the Bohai Bay Basin.

Lots of subaqueous gravity flow sedimentary bodies were developed in the Eocene strata of Chaluhe Fault Depression,the Yitong Basin.Based on the study of distribution and sedimentary character of gravity flow,four sedimentary types can be recognized: shallow-water and deep-water turbidity current deposits,underwater slide deposits and underwater debris flow deposits.Through the comprehensive analysis of regional geological background,drilling lithology,well loggings and seismic data,it is suggest that underwater slide deposits and underwater debris flow deposits were formed in re-transported and redeposition,which were usually associated with faults.Shallow-water and deepwater turbidity current deposits were developed in the pre-fan delta,and mostly related to the paroxysmal water flow event due to subaqueous distributary channel,and partially to the slump turbidity current redeposition.Based on the oil-gas exploration results,it shows that the turbidity sand-body has developed well reservoir capability and has a successful oil-gas exploration.It has been proved that shallow-water and deep-water turbidite sand bodies have good potentials for oil and gas exploration in this region,which are in Liangjia structural belt of the down-thrown side of the No.2 fault and in the periphery of Wanchang structural belt.