鄂尔多斯盆地西缘奥陶系乌拉力克组海相页岩岩石物理特征实验研究  

Experimental research on the rock physical properties of Ordovician Wulalike Formation shale in western Ordos Basin

作　　者：邓继新 徐小兵 徐中华 闫龙龙 黄军平[3] 谭开俊[3] 史江龙 DENG JiXin;XU XiaoBing;XU ZhongHua;YAN LongLong;HUANG JunPing;TAN KaiJun;SHI JiangLong(Key Laboratory of Earth Exploration and Information Technology of Ministry of Education(Chengdu University of Technology),Chengdu 610059,China;Department of Geophysics,College of Geophysics,Chengdu University of Technology,Chengdu 610059,China;PetroChina Research Institute of Petroleum Exploration Development-Northwest,Lanzhou 730020,China)

机构地区：[1]地球勘探与信息技术教育部重点实验室(成都理工大学),成都610059 [2]成都理工大学地球物理学院地球物理系,成都610059 [3]中石油勘探开发研究院西北分院,兰州730020

出　　处：《地球物理学报》2025年第3期1130-1147,共18页Chinese Journal of Geophysics

基　　金：国家自然科学基金项目(42474149,41774136);中国石油天然气股份有限公司前瞻性基础性战略性技术攻关项目(2021DJ0401)联合资助.

摘　　要：鄂尔多斯盆地西缘乌拉力克组海相页岩具备油气勘探开发的有利地质条件,是下一步盆地油气勘探开发的重要接替区,但由于对储层岩石物理特征缺乏系统研究,制约了页岩油层系地质与工程“甜点”地震评价方法的有效运用.为此,通过对乌拉力克组海相页岩样品的岩石学特征、储层特征和岩石物理特征的系统测试,揭示了沉积环境变化对页岩岩石学特征的影响,分析了页岩样品的岩石物理变化规律.研究结果表明,乌拉力克组海相页岩岩石学特征受沉积古地貌控制,岩性在横向展布上由上斜坡沉积环境的钙质页岩演变为斜坡洼地沉积环境的混合质页岩直至广海陆棚环境的硅质页岩,矿物组分上表现为生物石英含量逐渐增多,组成颗粒粒径逐渐减小,纹层组合特征由钙质纹层为主转变为“硅质纹层+黏土质纹层”为主.页岩样品纹层组合差异造成岩石受力骨架弹性性质改变,从而控制了地震弹性性质的整体变化方式,表现为垂直层理传播纵、横波速度随石英含量变化整体近似呈“V”型趋势,支撑颗粒相似的页岩样品不同方向纵、横波速度关系表现出较好的统计关系,硅质页岩具有最低的纵、横波速度比值,灰质页岩则表现出相对较高的纵、横波速度比值,孔隙度-速度变化关系也具有按组分和纹层组合特征分层分布的特征,孔隙度是影响速度变化的次一级因素.低黏土含量的硅质页岩和灰质页岩速度各向异性主要表现为纹层组合弹性性质差异的贡献,高黏土含量的混合质页岩和硅质页岩速度各向异性则受黏土质纹层中黏土颗粒定向程度和纹层组合弹性性质差异的共同影响,有机质对各向异性贡献较小.研究结果可为乌拉力克组页岩储层“双”甜点的测井与地震评价提供实验基础和理论支撑.Wulalike Formation shale in the western margin of the Ordos Basin has favorable geological conditions for hydrocarbon exploration and development,and is an important succeeding field for the next step of hydrocarbon exploration in the basin.However,due to the lack of systematic research on the rock physical characteristics of this reservoir,the effective application of seismic method on the geological and engineering“sweet spot”evaluation is restricted.Therefore,through the systematic testing of the petrological characteristics,reservoir characteristics and rock physical characteristics of shale samples from Wulalike Formation,the impact of changes in sedimentary environment on the petrological characteristics of shale was revealed,and the variation patterns of rock physical properties in shale samples are also analyzed.The results show that the petrological characteristics of marine shale in the Wulalike Formation are controlled by sedimentary paleogeomorphology.The lithology evolved from the calcareous shale in the upper slope sedimentary environment to the mixed shale in the slope depression sedimentary environment and to the siliceous shale in the open marine shelf environment.Correspondingly,mineral composition shows a gradual increase in the content of biogenic quartz and the grain size decreases gradually,and lamina combination changes from calcareous lamina to“siliceous lamina+argillaceous lamina”.The lamina combination variations cause the change of load-bearing phase of rock skeleton,which exerts primary control on seismic elastic behavior of the shale samples.As a result,the velocities of bedding normal compressional and shear wave shows a clear“V”shaped trend with the change of quartz content.Also,shale samples with similar load-bearing matrix show a good statistical relationship of compressional and shear wave velocities,and siliceous shale has the lowest ratio of compressional and shear wave velocity,while calcareous shale exhibits a relatively high ratio of compressional and shear wave

关 键 词：岩石物理特征 海相页岩 乌拉力克组 鄂尔多斯盆地西缘 

分 类 号：P631[天文地球—地质矿产勘探]