Application of Organic Inclusion in Oil-Gas Migration of Sichuan Reservoir of Southwest Sichuan Basin
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摘要: 有机包裹体在油气成因、运移和演化研究中具有重要的意义.川西南震旦系灯影组储层中次生成因孔洞缝发育, 经历了多期白云石和硅质充填.对不同期次充填矿物中的有机包裹体特征及荧光进行了观察, 测定了各期盐水包裹体均一温度, 其主峰分布在120~150℃、160~190℃和200~210℃; 并采用真空破碎法对各期有机包裹体的化学成分及碳同位素组成进行了分析, 其化学成分以CH4和CO2为主, 各期中的w(CH4)含量分别为10.09%~22.08%、27.06%~40.40%和55.33%~74.01%, 相应的w(CO2)/w(CH4)值为3.37~5.87, 1.20~2.20和0.26~0.63.CH4和CO2的碳同位素组成分别为(-50.7~-28.4)×10-3和(-18.3~-3.6)×10-3.据此追述了研究区油气的成因性质、油气的演化和运移.结果表明, 研究区震旦系灯影组储层的天然气为油型气; CO2主要为有机成因, 有少量为无机成因; 研究区存在有3期以上的油气运移, 且各期油气演化程度不同.Abstract: Organic inclusion is of great importance to the study of development, migration and origin of oil and gas. In Southwest Sichuan basin there are many pores, holes and fractures in the Sinian Dengying reservoir. The pore spaces were filled by dolomites and quarters of different stages. This paper analyzes the characteristics, fluorescence, homogenization temperatures, and chemical and isotopic compositions of the organic inclusions in the filled minerals of different stages. The homogenization temperatures of the organic inclusions in different stages distribute between 120-150 ℃, 160-190 ℃ and 200-(210 ℃). The chief chemical composition of the organic inclusions is CH4 and CO2. CH4 contents of different stages' inclusions are respectively 10.09%-22.08%, 27.06%-40.40%, 55.33%-74.01%, corresponding values of their CO2/CH4 content being 3.37-5.87, 1.20-2.20, 0.26-0.63. On this basis, the authors analyze the stages of the origin, development, migration and accumulation of oil and gas. Results show that the natural gas is oil-generating. CO2 is of organic origin and there is a little inorganic CO2. There are three stages of migration and accumulation of oil and gas in the Sinian Dengying reservoir, which are different in history of development.
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表 1 威远、资阳地区3期矿物中包裹体类型组合和均一温度
Table 1. Association types of hydrocarbon inclusions and homogenization temperature in the filled minerals of three stages in Weiyuan and Ziyang
表 2 威远、资阳地区三期矿物中包裹体主要化学成分和碳同位素组成
Table 2. Chief composition of chemistry and carbonic isotope of inclusions in the filled minerals of three stages in Weiyuan and Ziyang
表 3 威远、资阳地区3期矿物中有机包裹体与油气演化阶段的关系
Table 3. Organic inclusion and their related organic maturity and evolvement stages of oil-gas in the filled minerals of three stages in Weiyuan and Ziyang
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