【作者】 黄晶；

【导师】 王振奇；

【作者基本信息】 长江大学 ， 矿物学、岩石学、矿床学， 2020， 硕士

【摘要】 苏北盆地勘探重点为油藏,气藏研究相对薄弱。在油藏不断发现的同时,也发现了多个天然气藏。但由于天然气的工作仅仅处于起步阶段,勘探程度较低,天然气的类型、成藏模式及勘探潜力尚待明确。近年来在高邮凹陷浅层(<1500m)已发现稠油藏与伴生气藏,但从气藏规模来看,其含气面积较小,储量规模比较有限,平面上分布零散,勘探难度大,因此需理清此类气藏的来源、成藏主控因素并明确其成藏模式。本文首先结合油藏资料、地化分析资料,分析得出该类天然气为原油降解生物气,确定了其与稠油藏的伴生关系,明确了稠油藏形成的条件。随后以油-气输导体系作为主线,对气藏形成条件及主控因素做了深入研究,并指出了油气的成藏特征,建立了高邮凹陷浅层原油降解生物气成藏模式,为高邮凹陷下步勘探部署提供了依据。对原油物性、族组成、色谱图等有机地球化学资料分析显示,高邮凹陷浅层稠油为次生稠油,发生稠化的主要原因是生物降解作用,稠变程度主要受控于温度、地下水型、矿化度等的影响,其中矿化度的影响较为明显;通过天然气组分特征和碳同位素分析表明,浅层天然气属油藏遭厌氧微生物降解而形成,具有次生生物气的特征,比如甲烷含量高、非烃气体中氮气含量较高、丙烷碳同位素与二氧化碳碳同位素组成偏重、甲烷碳同位素组成偏轻等特点。同时发现高邮凹陷浅层气与原油生物降解后的稠油藏具有伴生关系,在成因上具有亲缘关系。通过对断阶带黄珏、周庄气藏和斜坡带韦庄气藏进行对比分析后得出以下结论:生物气成藏主控因素为稠油藏周边断层侧向运移能力以及盖层封堵能力;生物气成藏模式主要分为源内(气顶气)和源外(气层气)两类,源所指的是稠油藏,源内降解气藏基本与稠油藏同属一个圈闭,基本未发生明显运移,主要发育于斜坡带阜宁组地层内;源外降解气藏主要发育于断阶带戴南组、三垛组及盐城组地层内。更多还原

【Abstract】 The focus of exploration in the North Jiangsu Basin is on oil reservoirs,and gas reservoir research is relatively weak.Along with the continuous discovery of oil reservoirs,several natural gas reservoirs have also been discovered.However,because the work of natural gas is only in its infancy,and the degree of exploration is low,the type,accumulation pattern and exploration potential of natural gas have yet to be clarified.In recent years,heavy oil reservoirs and associated gas reservoirs have been discovered in the shallow layers(<1500m)of Gaoyou dimple.However,from the perspective of gas reservoir size,the gas-bearing area is small,the reserves are relatively limited,the distribution is scattered on the plane,and the exploration is difficult.Therefore,it is necessary to clarify the source of such gas reservoirs,the main controlling factors of accumulation,and clarify their accumulation patterns.This paper first combines the reservoir data and geochemical analysis data to analyze that this type of natural gas is crude oil-degrading biogas,confirms its associated relationship with heavy oil reservoirs,and clarifies the conditions for the formation of heavy oil reservoirs.Subsequently,the oil-gas transmission system was used as the main line to make an in-depth study on the formation conditions and main controlling factors of the gas reservoir,and pointed out the hydrocarbon accumulation characteristics,and established a shallow crude oil degradation biogas accumulation model in Gaoyou dimple.The next step of exploration and deployment in the sag provides a basis.Analysis of crude oil physical properties,family composition,chromatograms and other organic geochemical data shows that the shallow heavy oil in Gaoyou dimple is a secondary heavy oil.The main reason for thickening is biodegradation,and the degree of thickening is mainly controlled by temperature and groundwater The influence of type,salinity,etc.,of which salinity is more obvious;analysis of natural gas composition and carbon isotope analysis shows that shallow natural gas reservoirs are formed by the degradation of anaerobic microorganisms and have the characteristics of secondary biogas For example,high methane content,high nitrogen content in nonhydrocarbon gas,heavy carbon isotope composition of carbon isotope of carbon dioxide and carbon isotope composition of methane,and lighter carbon isotope composition of methane.At the same time,it was found that the shallow gas in the Gaoyou dimple has an associated relationship with the crude oil biodegraded heavy oil reservoir,and is genetically related.By comparing and analyzing Huang Jue,Zhouzhuang Gas Reservoir and Weizhuang Gas Reservoir in the slope belt,the following conclusions are drawn: the main controlling factors of biogas accumulation are the lateral migration ability of the faults around the heavy oil reservoir and the sealing of caprock Biomass accumulation model is mainly divided into two types: in-source(gas cap gas)and out-source(gas layer gas).The source refers to the heavy oil reservoir,and the in-source degraded gas reservoir basically belongs to the same trap as the heavy oil reservoir.There is basically no obvious migration,which is mainly developed in the formation of Funing Formation in the slope belt;the out-source degraded gas reservoir is mainly developed in the formation of Dainan Formation,Sanduo Formation and Yancheng Formation in the fault terrace belt.更多还原