北黄海盆地上侏罗统烃源岩测井评价

北黄海盆地尚处于勘探早期,盆地内烃源岩厚度巨大,但钻井取心较少,测试样品有限,难于对该区的烃源岩条件作出整体评价。文中结合地层沉积特征和地球化学测试数据,利用Δlog R技术,根据有机质在测井曲线上的响应特征,考虑岩性组合的差异,建立了适合研究区不同岩性组合的2种有机质丰度测井解释模型,获得钻井剖面上连续分布的总有机碳质量分数信息。研究表明:北黄海盆地东部坳陷上侏罗统烃源岩发育,上部J3SQ2层序中烃源岩厚度50~300 m,坳陷中心总有机碳质量分数大部分高于1.5%;下部J3SQ1层序中烃源岩厚度50~200 m,总有机碳质量分数0.5%~2.0%。2套层序中烃源岩总有机碳质量分数均表现出由坳陷中心向四周降低的特征。整体上,研究区上侏罗统烃源岩以中等烃源岩为主,具有生成油气的物质基础,邻近生烃中心的构造带应具有较好的勘探前景。

Logging evaluation of Upper Jurassic source rocks in North Yellow Sea Basin

The North Yellow Sea Basin is still in the early stage of exploration,in which the thickness of the source rocks is considerable.But it is difficult to overall evaluate the source rocks conditions with the limited core test samples.Based on the stratigraphic sedimentary characteristics and geochemical test data,according to the response characteristics of organic matter on logging curve,two TOC logging interpretation models for different lithology combination were built using △log R technology.The organic carbon contents of the continuous distribution in the drilling wells were obtained.The research results show that the thickness of the source rocks in J3SQ2 ranges from 50 to 300 m.Major TOC contents reach 1.5％ in the depression center.The thickness of source rocks in J3SQ1 ranges from 50 to 200 m and the TOC contents range from 0.5％ to 2.0％.From the depression center to the surrounding,TOC contents decrease gradually.In summary,the Upper Jurassic source rocks in the North Yellow Sea Basin can be considered as medium source rocks and have the material basis for the formation of oil and gas.So the targets close to the main "hydrocarbon kitchen" can be the favorable targets in the further exploration.