塔中顺西地区奥陶系油气藏特征及成藏主控因素

Characteristics of Ordovician Oil&Gas Reservoir and Main Controlling Factors of Hydrocarbon Accumulation in Shunxi area,Middle of Tarim Basin

据岩心、薄片、地球物理、分析化验及试油等资料,对顺西地区奥陶系油气藏特征及成藏主控因素进行分析。认为顺西地区奥陶系原油为低粘度、低含硫的轻质原油,天然气主要显示湿气、碳同位素偏低特征,地层水矿化度高,为典型封闭环境下的氯化钙型。该区油气藏属常温常压-常温高压温压系统,油气藏类型以凝析气藏为主,次为轻质油藏。该区油气成藏主要受控于优质储层、多期活动断裂和喜马拉雅期气侵强度。该区奥陶系广泛发育的岩溶缝洞型储层为油气提供了良好的储集空间,是油气成藏的基础。多期次活动断裂不仅形成大量裂缝,有利于溶蚀作用的发生,形成溶蚀孔洞,且可作为油气源通道,沟通深部油气源,有利于油气运移,控制油气藏的形成。此外,喜马拉雅期天然气充注强度直接影响现今油气藏的分布,显示凝析气藏和油藏共存的基本格局。

Through core, thin section,geophysical,chemical analysis and oil test data, characteristics of Ordovician hydrocarbon reserviors and main controlling factors of reservoir formation are systematically analyzed in Shunxi area.Studies suggest that Ordovician crude oil is low viscosity, low sulfur, natural gas mainly show the characteristics of low carbon isotope and moisture,and belongs to the typical chloride-calcium type in the closed environment. The reservoir belongs to temperature pressure system of normal temperature and normal-high pressure, the types of oil and gas reservoir is mainly condensate gas reservoirs,followed by light oil reservoir.Further research shows that the hydrocarbon accumulation is controlled by the high quality reservoir, multiperiodic activities of fault and Himalaya gas invasion strength.The extensive fracture-vug reservoir in Ordovician provide good reservoir space for oil and gas,it is the foundation of petroleum entrapment; Multiperiodic activities not only form a large number of cracks, but also in favor of karstification,the formation of dissolved pores, can be used as a source of oil and gas channel,link up deep oil and gas, which is favorable for oil and gas migration and control the formation of oil and gas.In addition,filling intensity during Himalaya natural gas directly affects the distribution of the oil and gas reservoirs,reveal the basic coexistence pattern of the condensate gas reservoir and oil reservoir.