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Re和Os易于被有机物捕获而富集,并长期稳定地保存在烃源岩、原油和沥青中而保持良好的封闭体系。可以对烃源岩、原油和沥青进行Re-Os同位素直接定年,获得与油气成藏相关的精确的绝对年龄信息。Re-Os同位素实验分析包括样品的溶解、Re和Os的化学分离与纯化、Re和Os同位素的质谱测定。原油中沥青质组分的Re,Os同位素组成能够近似代表全油的Re,Os同位素组成,对原油进行Re-Os同位素分析实质就是对原油中的沥青质组分中的Re-Os同位素体系进行分析,其年龄记录的是油气生成的年龄,原油和烃源岩的187 Os/188 Os比值的对比可以进行油源示踪。沥青Re-Os同位素等时线年龄揭示的是油气大量生成运移的时间,年龄数据分散的主要原因是具有不同187 Os/188 Os初始比值的烃源岩对Re-Os体系的贡献。川西龙门山北段矿山梁下寒武统沥青Re-Os同位素组成和等时线年龄指示了油气生成和运移的时间发生在～164 Ma,并来源于两种烃源岩。Re-Os同位素体系的封闭性、等时线年龄的精度和油气地质意义、烃源岩多期熟化作用和混源作用的影响等方面还值得进一步深入研究。Re-Os同位素方法将在油气成藏年代学领域,特别是在碳酸盐岩地区的油气成藏定年方面具有广泛的应用前景。
Re and Os are easy to be captured and enriched by organic matter, and remain stable and stable in source rock, crude oil and bitumen for a long time and keep a good closed system. The Re-Os isotope dating of source rocks, crude oil and bitumen can be used to obtain accurate absolute age information related to hydrocarbon accumulation. Re-Os isotope analysis includes sample dissolution, chemical separation and purification of Re and Os, and mass spectrometry of Re and Os isotopes. The Re and Os isotopic composition of asphaltene in crude oil can approximately represent the Re and Os isotopic composition of whole oil. The Re-Os isotope analysis of crude oil is essentially carried out on the Re-Os isotope system in the asphaltene component of crude oil Analysis, whose age records the age of hydrocarbon generation, shows that oil source tracing can be achieved by comparing 187 Os / 188 Os ratios between crude oil and source rocks. The isochron age of Re-Os isotope of asphalt reveals the time of mass hydrocarbon migration. The main reason for the dispersion of age data is the contribution of source rocks with different initial ratios of 187 Os / 188 Os to Re-Os system. The Re-Os isotopic composition and isochron age of the Lower Cambrian ashes in the northern Beilingshan section of the western Sichuan Basin indicate that hydrocarbon generation and migration took place at ~ 164 Ma and originated from two source rocks. Re-Os isotopic system is closed, the accuracy of isochron age and petroleum geological significance, multi-stage maturation of source rocks and the influence of mixed source is worth further study. The Re-Os isotope method will have broad application prospects in the field of hydrocarbon accumulation and geochronology, especially in the hydrocarbon accumulation dating of carbonate rocks.