烃类包裹体荧光光谱技术在乌石凹陷油气成藏期次研究中的应用

Application of fluorescence spectroscopy of hydrocarbon inclusions in the study of hydrocarbon accumulation stages in Wushi sag

油气成藏期次确定是研究油气成藏过程的基础,乌石凹陷受包裹体资料限制,之前这方面的研究较少,因而该区油气成藏期次不清。为解决乌石凹陷流沙港组油气成藏期次确定这一难题,本研究基于流体包裹体新样品检测,运用荧光光谱方法,对乌石凹陷流沙港组油气充注期次及成藏时期进行了分析。结果表明:乌石凹陷流沙港组油包裹体荧光颜色丰富,观察到发亮黄色、黄绿色、蓝色3种不同的荧光;油包裹体主峰波长和红绿熵主要分布在亮黄色荧光区域和黄绿色、蓝色荧光区域,这两个区域主峰波长、红绿熵值存在明显降低的趋势,显示包裹体内油的成熟度增高;受油气来源及油气差异聚集的控制,乌石凹陷不同构造区块,油气充注期次及充注油气性质存在一定差别,流沙港组油层整体存在2期油气充注。该研究成果不仅有效解决了乌石凹陷成藏认识上的关键问题,对乌石凹陷油气勘探具有重要指导作用,同时对其他区域也具有较为广泛的借鉴作用。

The determination of hydrocarbon accumulation stages is the basis for the study of hydrocarbon accumulation process. Limited by the inclusion data, there have been few previous studies in the Wushi sag, so the hydrocarbon accumulation stages in this area are not clear. In order to solve the problems in the study of hydrocarbon accumulation stages of Liushagang Formation in Wushi sag, this paper analyzes the episodic combination and accumulation stages of hydrocarbon filling in Liushagang Formation in Wushi sag based on the new sample detection of fluid inclusions and by using fluorescence spectroscopy. The results show that the oil inclusions in Liushagang Formation in Wushi sag are rich in fluorescence color, and bright yellow, yellow-green and blue are observed. The main peak wavelength and red green entropy of oil inclusions are mainly distributed in the bright yellow fluorescent region and yellow-green and blue fluorescent region. The main peak wavelength and red green entropy of these two regions show a significant trend of decrease, indicating increasing maturity of the crude oil in the inclusions. Controlled by the source of hydrocarbon and the characteristics of differential accumulation, different structural blocks in Wushi sag have certain differences in hydrocarbon filling stages and properties, and there are two stages of hydrocarbon filling in Liushagang Formation as a whole. The research results not only effectively solve the key problems in the understanding of reservoir formation in Wushi sag, but also play an important guiding role in hydrocarbon exploration in Wushi sag. At the same time, it can also be widely referenced in other regions.