Study On Sandbody Distribution And Sedimentary Facies Of Neogene In Raoyang Sag

According to the theory of sequence stratigraphy and sedimentlogy, the paper has studied on the sequence stratigraphy and sedimentary facies of Neogene in Raoyang Sag using slice identification, heavy mineral, well logging, seismic section,well testing,and so on.The paper pointed out the main factors controlling hydrocarbon accumulation and distribution in the end.Based on the integrated analysis of cores,well logging,seismic data and other basic data,the sequence stratigraphy of Neogene of Raoyang Sag are studied.The Guantao formation of Neogene is one long-term base-level cycle, and which can be divided into three intermediate-term base-level cycles(Ng³,Ng²,Ng¹) and seven short-term cycles (Ng^3-3,Ng^3-2,Ng^3-1,Ng^2-2,Ng^2-1,Ng^1-2,Ng^1-1). The lower member of Minghuazhen formation can be divided into four intermediate -term cycles (Nm^2-4,Nm^2-3,Nm^2-2,Nm^2-1).According to sedimentary facies signature, facies types, analysis of single-well facies and cross-sectional facies, it is summarized as that there are two types of sedimentary facies of Neogene in Raoyang sag. Vertically, it is braided river in the bottom of Guantao formation, meandering fluvial in upper part of Ng³,Ng²,Ng¹,and lower member of Minghuazhen formation.Taking the research of palaeogeomorphology and distribution feature of sand bodies as background, basing on combination of heavy minerals and change of clastics content, it is pointed that the the provenances of Guantao formation in Raoyang sag is mainly derived from three derections with NNE, western and southwestern directions. The provenances of NNE influenced the deposition of Raoyang sag largely, the provenances of west and southwest not only provided deposition for Lixian, but also provided slight deposition for Yangwuzhai area. From the bottom to the top, influence of western and south-western provenances on the sedimentary facies of Raoyang sag increased.Uniting the research of provenances, sandbody distribution and seismic attributes,the paper studied characteristics of distribution and vertical evolution of sedimentary facies that belong to every term cycle in Raoyang sag.It is indicated that there are several river channels with NNE ribbon pattern distribution in the plane, and the phenomenon of divarication and aggregation between the river channels is very common.This paper has studied the reservoir-seal assemblage on the basis of sedimentary facies analysis, divided Guantao formation into three sets of reservoir-seal assemblage(Ng³,Ng²,Ng¹-Nm^2-4), favorable reservoir-seal assemblage and structural condition were the significant conditions controling hydrocarbon accumulation and distribution in Neogene of Raoyang sag. Liuxi-Liuchu structural zone, Hejian- Suning structural zone and Maxi-Nanmazhuang-Balizhuang structural zone are the favorable zones of Neogene in Raoyang sag.