鄂尔多斯盆地古隆起西侧奥陶系烃源岩评价及成藏模式
石 ib -b k f W j t A
第38卷第6期
OIL ( GAS GEOLOGY 2017年12月文章编号:0253 -9985(2017)06 -1087 -11doi ： 10.11743/ogg20170609鄂尔多斯盆地古隆起西侧奥陶系烃源岩评价及成藏模式
肖晖1!2,赵靖舟1!2,熊涛",吴伟涛1!2,米敬奎4,刘素彤1!2
(1.西安石油大学地球科学与工程学院，陕西西安710065! 2.西安石油大学陕西省油气成藏地质学重点实验室，陕西西安710065!
3.中国石油长庆油田分公司第五采油厂，陕西西安710200;
4.中国石油勘探开发研究院，北京100083)
摘要:基于鄂尔多斯盆地古隆起西侧奥陶系有效烃源岩评价，证实了在该地区斜坡低部位发育有源自奥陶系内部烃源岩的气藏新 类型。根据11 口钻井347块烃源岩样品分析，中上奥陶统台地边缘斜坡相带发育良好烃源岩。乌拉力克组和克里磨里组烃源岩有 机质含量高，泥灰岩含量平均值分别为0.33%和0.39%，泥质岩类TO C 含量平均值分别为0.51 %和0.65%，有效烃源岩 累计厚度分别在12?40 m 和7?14 m ，局部烃源岩厚层发育区，生气强度达（14.0?15.5) x 108m3/km2,证实具有较好的生烃潜力。 研究区奥陶系气藏主要经历两期成藏过程：早期为中侏罗世，奥陶系烃源岩生烃形成古油藏，晚期为晚侏罗世一早白垩世，古油藏 裂解形成油型气。晚期气烃包裹体甲烷碳同位素平均值在-38. 84%。，证实晚期具有油型气充注特征。古隆起西侧斜坡高部位普遍 发育煤成气气藏，在克里磨里组斜坡低部位大量发育碎屑钙质角砾岩，与上覆中上奥陶统有效烃源岩近距离接触，侧向上远离奥陶 系顶面风化壳，能够形成自生自储型气藏类型，如余探1井气藏。台缘斜坡带低部位发育的岩溶缝洞体，是寻找该类气藏的有利勘
区。
关键词：成藏模式；烃源岩；奥陶系；下古生界;鄂尔多斯盆地
中图分类号:TE121.2 文献标识码:A
Evaluation of Ordovician source rocks and natural gas accumulation patterns in west flank of a paleo-uplift，Ordos basin
Xiao Hui1，2，Zhao Jingzliou1，2，Xiong
Tao3，Wu Weitao1，2，Mi Jingkui4，Liu Sutong1，2(1. School of Earth Sciences and Engineering，XV an Shiyon University，XV an，Shaanxi 710065，China ；
2. Key Laboratory of Hydrocarbon Accumulation of Shannxi Province ，Xi' an Shiyon University，XV an，Shaanxi 710065，China ；
3. No. 5 OH Profuction Plant，PetroChina Changqing Oilfield Company ，Xi' an，Shaanxi 710200，China ；
4. PetroChina Research Institute 〇o Petroleum Exploration & Development，Beijing 100083，China)
Abstract ：T he existence of a new gas accumulation type sourced from the source rocks witliin the Ordovician was con -firmed at tlie l ower slope in the west flank of a paleo-uplift in Ordos Basin based on ?fective source rock asessment re -sults . Analyses of 347 samples taken from the source rock intervals in 11 wells revealed high-quality source rocks devel -oped in marginal slopes of tlie middle and upper Ordovician platform in the Basin . Measurements showed that tlie source rocks in the Wulalike and Kelimoli Formations had relative higher !OC values ，with marlite !OC averaged a t 0.39 %，and mudstone TOC averaged at 0. 51 % and 0. 65 %，respectively . The accumulative effective thicknesses of source rocks of t!ie two formations were 12 to 40 m and 7 to 14 m ，resjoectively . Areas wit!i thick source rocks were as -sessed to have a gas generation capacity of 14. 0 x 108 to 15.5 x 108 m3/km 2. Gas accumulations in the Kelimoli Forma -tion experienced two charging stages ： the early stage in the Middle Jurassic，during which paleo-oil reservoirs were formed ； and the late stage in the Late Jurassic to Early Cretaceous，during which the paleo-oil reservoirs were cracked into petroliferous gas reservoirs . Carbon isotopes of gas-bearing inclusions from the later stage were measured to be - 38. 84% in average，indicating late petroliferous gas charging characteristics . Coal-derived gas reservoirs were distributed widely in the upper slope in the west flank of the paleo-uplift . The fact that the massive detrital ca Kelimoli Formation at the lower slope had a close contact with the overlying effective source rocks of th
收稿日期:2016-12-14;修订日期:2017-10-8。第一作者简介：肖日军（1980—)，男，博士，副教授，油气成藏地质学。E-mail :xiaohui@ xsyu. edu. cn 。
基金项目：国家自然科学基金项目（41102082);陕西省科技厅研究发展计划项目（2012 J 5011);陕西省教育厅重点研究计划（17 J S109)