Beach-Bar Sedimentary Research And Advantageous Region Prediction Of The Second Member Of Shahejie Formation In Zhuangxi Area Of Zhanhua Sag

This paper use the high resolution sequence stratigraphy theory and method of terrigenous facies, on the basis of rock core and drilling/logging data, carry on the studying of sedimentary facies and the division and contrast of the high frequency sequence (four-order sequence) of the second member of Shahejie formation in Zhuangxi area, forecast the distributed area of commercial reservoir.By the studing of this paper, we recognized three kinds of sedimentary systems (fan delta system,beach-bar system and lacus system) and six kinds of sedimentary facies (fan delta, sand-beach, sand-bar, biogenic limestone beach, bend and lshore-shallow lake) in all of the Second Member of Shahejie Formation in Zhuangxi Area.By picking across the all research area, Zhuangxi area only develop Es21. With the analysis development of sequence, the paper shows that it is sequential deposition between the second member of Shahejie formation and the first member of Shahejie formation.They constitute three-order sequence on the whole .Depending on rock core and drilling/logging data,we divide Es21 into two parts (falling hemi-cycles and rising hemi-cycles,be equal to four-order sequence).According to sedimentary system and sedimentary facies analysis of the second member of Shahejie formation in Zhuangxi area,we create the sedimentary faces model of Es21 . Fan delta and sand-beach develop in the east of Zhangxi buried hill. Biogenic limestone beach develops in the west of Zhangxi buried hill. Bioclast beach develops in the north of Zhangxi buried hill. Sediment supply, hydrodynamics ,buried hill existence and buried hill shape mainly control beach-bar distribution.Moreover, palaeogeomorphology importantly impacts beach-bar sand development in the secondary building unit (actic region, gentle slope region, subaqueous palaeohigh and so on) of the lake basin.Sand-beach and Bioclast beach is the more beneficial reservoir in the buried hill rim area because their reservoir physical property is better. Depending on sedimentary characteristic and structural characteristic of Es21, the area has good conditions of generating oil. Study shows beach-bar around Zhuangxi buried hill has good petroleum resource potential.