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轮南地区油气藏的分布十分复杂,各种不同物性的原油如重质油、正常油、蜡质油、轻质油和凝析油均有分布,并呈现“西重东轻”、“西油东气”和“上下重,中间轻”的分布格局。运用原油正构烷烃半对数分布、生物标志化合物比值和稳定碳同位素组成等精细的有机地球化学分析表明,原油地球化学特征平面分布上与大的“东西分异”背景相吻合,且具有通常成熟度连续的单期烃类充注、成藏难以解释的“两族、不连续分布”特征。轮南地区油气藏存在东部和西部两个油族,西部地区油族成熟度略低且有生物降解痕迹,主要以重油形式分布;东部地区油族成熟度略高,主要以轻质油、凝析油形式存在,中间地段发生的混合作用形成了中-高蜡油。混合成藏作用模式,可能有助于解释轮南地区油气藏(包括蜡质油)的分布规律,并能对原油物性、含氮化合物、生物标志化合物、稳定碳同位素组成等各项地球化学数据作出相对较为一致的解释。
The distribution of oil and gas reservoirs in Lunnan area is very complicated. All kinds of crude oil with different physical properties such as heavy oil, normal oil, waxy oil, light oil and condensate oil are distributed, showing “west heavy east”, “west Oil East ”and“ up and down heavy, light in the middle ”of the distribution pattern. The fine organic geochemical analysis of semi-log distribution of n-alkanes, biomarker ratios and stable carbon isotopic composition of crude oil shows that the geochemical characteristics of crude oil are in good agreement with the large “east-west differentiation” The single-phase hydrocarbon with mature maturity is characterized by “bicommunal and discontinuous distribution” which is difficult to explain in the accumulation of hydrocarbon. There are two oil reservoirs in eastern and western part of Lunnan oil and gas reservoirs. The oil maturity in western part is slightly lower and has biodegradation traces, mainly distributed in the form of heavy oil. In the eastern part, the oil maturity is slightly higher, mainly in light oil and condensate The oil-in-oil form exists and the middle-high waxy oil forms as a result of the mixing action in the middle section. The mixed mode of accumulation and accumulation may help to explain the distribution of oil and gas reservoirs (including waxy oil) in Lunnan area. The geochemical data of crude oil physical properties, nitrogenous compounds, biomarkers and stable carbon isotope composition Make a relatively consistent explanation.