鄂尔多斯盆地杏子川油田长9烃源岩特征及油气勘探意义

Characteristics of Chang 9 member source rocks and its significance of hydrocarbon exploration in Xingzichuan Oilfield,Ordos Basin

应用岩石热解、干酪根镜检、同位素、气相色谱及色谱-质谱等分析方法,对鄂尔多斯盆地杏子川油田延长组长9暗色泥岩有机地球化学特征及油气勘探意义进行研究。结果表明:杏子川油田延长组长9烃源岩主要为长91段顶部的李家畔页岩,长92暗色泥岩地球化学特征表明其为非油源岩;长9烃源岩主要由粉砂质或含粉砂泥岩组成,并非真正意义上的黏土岩;有机碳质量分数平均为3.05%,干酪根类型主要为Ⅱ1型,最高热解峰温平均为450℃,反映烃源岩达到好的级别,处于成熟演化阶段;烃源岩母质类型主要以低等水生生物和高等植物共同输入为特征,湖盆水体环境总体以淡水还原条件为主;长9烃源岩具有较好的生烃条件,以生油为主,烃源岩厚度大于10 m地区为长8～长10油藏有利勘探区。

By using rock pyrolysis, microscopic examination of kerogen, istope, gas chromatography, GC-MS and other anal-ysis methods, the organic geochemical characteristics of the dark mudstone of Chang 9 member in Upper Triassic of Xingzi-chuan Oilfield in Ordos Basin and its significance of hydrocarbon exploration were studied. The results show that the main source rocks in study area are Lijiapan shale at the top of Chang 9^1 , and the geochemical characteristics of the dark mudstone of Chang 9^2 show that they are not the petroleum source rocks. The source rocks on Chang 9 mainly consist of silty or silt-bearing mudstone, which are not the real clay rocks. The average organic carbon content is 3. 05%, and the main kerogen type is type Ⅱ1, and the average highest pyrolysis peak temperature is 450 ℃. These show that the source rocks rank is good ones and in the mutual stage. The types of parent materials are characterized by the common input of the lower aquatic organ-isms and higher plants, and the water environment of lake basin is the fresh water reduction condition as a whole. The com-prehensive evaluation shows that Chang 9 develops the better hydrocarbon-generating condition, which tends to generate oil. The region whose thickness is over 10 m is the favorable exploration target area of Chang 8 to Chang 10 petroleum accumula-tions.