基于酸解烃判别台湾海峡盆地西部坳陷含油气系统的油气藏属性

Oil and gas reservoir attribute discrimination based on surface sediment acid-extraction hydrocarbon in the western depression of Taiwan Strait Basin

台湾海峡盆地西部被认为具有较好的油气资源前景,而前期的研究成果仅局限于地球物理方面的资料,尚缺少地球化学方面的信息来证实。本研究通过对该区晋江凹陷和九龙江凹陷的海底沉积物中酸解烃含量及其碳同位素组成特征进行分析,研究该区含油气系统中烃类渗漏的地表响应,探讨其烃类来源,进而判别下伏油气藏属性特征,为进一步油气勘探提供可靠的油气地球化学信息。研究结果表明,该区烃类存在两个气体来源,可能与研究区内的两套烃源岩有关,源1以油型气为主,源2则以干气为主。两个气源对研究区内两个凹陷的贡献不同,九龙江凹陷以源1为主,源2对该区存在一定的贡献;而晋江凹陷则主要为源2。

Taiwan Strait basin is commonly regarded as a good petroleum-bearing area. However,the previous studies were all focused on the data from geophysics,with no direct evidence from petroleum geochemistry to prove the existence of economic oil or gas reservoirs in these areas with good petroleum prospects. In this study,the concentrations and carbon isotope ratios of the soil acid-extraction hydrocarbon from the sea surface sediments in Jinjiang depression and Jiulongjiang depression of west Taiwan Strait basin were analyzed to study the microseepage and origins of the petroleum-baring system,with the purpose of providing the proven geochemical information for petroleum exploration. The result of surface geochemical exploration for oil and gas in the west Taiwan Strait basin indicates that there exist two kinds of hydrocarbon resources： one is oil-gas and the other is single dry gas,probably related to two suites of source rocks in this area. These two kinds of resources make different contributions to the two depressions in the study area,where hydrocarbon of the Jiulongjiang depression is mainly from source 1,and source 2 mainly contributes to the hydrocarbon reservoir of Jinjiang depression.