Study On Hydrocarbon Accumulation Characteristics In The Western Slope Area,Southern Of Songliao Basin

The study on hydrocarbon accumulation characteristics in western slope area,south of Songliao basin is based on sorting geological data and geochemical data,which include the results of latest geochemical experiment and previous understanding of geological phenomenon.It is analyzed that what the source of the heavy oil in Taobao area is,where it comes from,and the characteristics of hydrocarbon display in the process of migration in the slope area.On the basis of oil sources and migration paths,the causes of heavy oil and main controlling factors of hydrocarbon accumulation are discussed,which influence accumulation modeling in the slope and indicate the favorable exploration area.The main conclusions are drawn as follows:the main source of oil in Taobao area is Qingshankou Formation in Yingtai area,which contributes much more than Changling Depression.The main causes of heavy oil are serious biodegration and chromatography role by long-distance migration.With increasing degree of formation water reworking,the index of rNa/rCl,100×rSO4/rCl,rHCO3+rCO3/rCa,rCa/rMg increase as well,which indicate worse condition of hydrocarbon preservation.Oil and gas show in the Number 1 of Nenjiang Formation,Number 1,2+3 of Yaojia Formation,Number 1,2+3 of Qingshankou Formation and Number 4 of Quantou Formation in western slope,and Number 2+3 of Yaojia Formation is the main path in hydrocarbon migration.Ts/(Ts+Tm),C29? ? ?/(? ? ? + ? ? ?),C30 rearranged hopanoid/C30 hopanoid are reasonable maturity-biomarker indexes,which.could indicate that main hydrocarbon contribution in west slope area comes from formations at Yingtai area.Analyses of core sample might indicate only one period of reservoir forming,while there is still a possibility that hydrocarbon from Gulong Depression did not spread to Da'an area as a result of limitation of sample collection.According to planar divisibility of structure,sedimentary and fluid properties,seven reservoir-forming units are divided.Typical model of western slop indicates probable exploring areas which are consist of lithologic reservoir in Anguang and Pinganzhen areas and stratigraphical overlap reservoir in the edge of basin.