准噶尔盆地玛南地区风城组烃源岩地球化学特征及有效性差异

Differences of effectivity and geochemical characteristics of the Fengcheng Formation source rock in Ma’nan area of the Junggar Basin

玛南地区位于准噶尔盆地西北缘玛湖凹陷西南部。基于该区部分钻井烃源岩的有机碳、热解、岩心、岩石薄片与荧光薄片等分析测试成果,主要对研究区风城组二段与风城组三段烃源岩的基本有机地球化学特征和有效性进行了对比分析。结果表明:已有钻井的风城组烃源岩主要集中于风二段和风三段。风二段烃源岩母质的倾油性强于风三段,生烃潜力也明显更高。综合考虑成熟度参数特征和影响因素,认为烃源岩主要处于成熟生油阶段。由于母质类型和生烃能力的差异,风二段有效烃源岩的有机碳含量下限值大致为0.7%,而风三段为2%左右。由于受可溶有机质含量、TOC含量等因素的影响,在利用热解T;分析烃源岩热演化特征时应慎重。风城组烃源岩既可以形成源外油气资源,也可以形成源岩层系内的页岩油资源。

The Ma’nan area is located in the southwest part of the Mahu Sag in the Junggar Basin. Based on the total organic carbon content(TOC), Rock-Eval pyrolysis, core, rock thin section and fluorescence chip, the authors contrast the organic geochemical characteristics and effectivity of the second and the third members source rocks of the Fengcheng Formation in the study area. The Fengcheng Formation source rock samples from the boreholes were sampled from the second and the third members. There are higher oil-generating capability and potential and in the second than in the third member. Depending on maturity parameters and their influencing factors, the source rock was thought in the mature oil-generating stage. Because of differences of organic matter type and hydrocarbon-generating capability, the low limit value of the second member TOC of the Fengcheng Formation is 0.7% and 2% for the third member. Because of soluble organic matter and TOC content influence, it should be careful to analyze the thermal evolution characteristics of source rocks by using Rock-Eval T;. The Fengcheng Formation source rock may not only hydrocarbon accumulation outside source rock layer but also shale oil resource inside the source rock layer.