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鄂尔多斯盆地西部奥陶系乌拉力克组 烃源岩沉积模式及生烃潜力

作    者:吴东旭1,2,吴兴宁1,李程善3,于 洲1 ,李维岭1, ,蔡 君1, ,李国军1,2 ,李程善3 , ,李程善3 ,李程善3 ,李程善3 ,李程善3 , ,吴兴宁1 ,李程善3 ,于 洲1 ,李维岭1 ,蔡 君1 ,李国军1,2
单    位:中国石油杭州地质研究院;2 中国石油集团碳酸盐岩储层重点实验室;3 中国石油长庆油田公司勘探开发研究院
基金项目:本文受国家科技重大专项下属课题“深层古老含油气系统成藏规律与目标评价”资助
摘    要:
随着鄂尔多斯盆地天然气勘探日益向深层发展,下古生界的烃源岩发育规模和生烃潜力成为制约天然气勘 探的重要因素。基于野外露头、钻井岩心和薄片观察,结合全岩矿物、有机碳、稀土元素、干酪根、镜质组反射率、热解 等地球化学分析,对盆地西部奥陶系乌拉力克组烃源岩的沉积模式和生烃潜力进行了详细研究。沉积相研究表明: 盆地西部乌拉力克组主要发育浅水灰质陆棚相、深水陆棚相和海槽相 3个相带,其中的深水陆棚相由于水体安静且 处于氧化界面以下,是烃源岩发育和保存的良好相带,而海槽相由于受到重力流、浊流等的影响,水体动荡,不利于烃 源岩的保存。烃源岩分析表明:深水陆棚相大部分地区的烃源岩TOC超过0.4%,干酪根以Ⅰ型为主,含少量Ⅱ1型,烃 源岩普遍达到成熟—高成熟演化阶段,是有效的产气源岩。以0.4%为有效烃源岩的TOC下限,计算得到乌拉力克组 的总生烃量达到8.226×108 t,可以为盆地西部奥陶系储层提供充足的天然气。
关键词:深水陆棚;烃源岩;生烃潜力;乌拉力克组;奥陶纪;鄂尔多斯盆地西部

Sedimentary model and hydrocarbon-generation potential of source rock of the Ordovician Ulalik Formation in western Ordos Basin

Author's Name: WU Dongxu, WU Xingning, LI Chengshan, YU Zhou, LI Weiling, CAI Jun, LI Guojun
Institution: 
Abstract:
With the development of natural gas exploration in deep strata, the scale and hydrocarbon-generation potential of the Lower Paleozoic source rocks in Ordos Basin have become an important factor. Based on field outcrop, drilling core and thin section observation, combined with geochemical analysis of minerals, organic carbon, rare earth elements, kerogen, vitrinite reflectance, pyrolysis and so on, the sedimentary model and hydrocarbon-generation potential of Ordovician Ulalik Formation in western basin are studied in detail. The study of sedimentary facies shows that Ulalik Formation is mainly composed of three facies belts, i.e., shallow-water calcareous shelf facies, deep-water shelf facies, and trough facies. The deep-water shelf facies is favorable for the development and preservation of source rocks due to the quiet water body and being under the oxidation interface, however, the trough facies are not conducive to the preservation of source rocks due to the influence of gravity flow and turbidity current. The source rocks of deep-water shelf facies are effective for gas generation: TOC is mostly more than 0.4%, kerogen is mainly type I and a little type Ⅱ1, and the source rock is generally in the stage of maturity-high maturity. Taking 0.4% as the lower limit of TOC of effective source rock, the total amount of hydrocarbon generated by Ulalik Formation is 8.226 × 108 t, which can provide sufficient natural gas for Ordovician reservoirs in the western basin.
Keywords: deep-water shelf; source rock; hydrocarbon-generation potential; Ulalik Formation; Ordovician; western Or⁃ dos Basin
投稿时间:2019-12-19  
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