【作者】 李聪；

【导师】 陈世悦；

【作者基本信息】 中国石油大学 ， 地质学， 2011， 博士

【摘要】 白云岩成因一直是沉积学领域的研究热点之一。论文在对前人相关研究成果充分调研的基础上,以碳酸盐岩岩石学、储层地质学等基础理论为指导,充分利用岩芯、钻井、录井、测井资料,结合镜下鉴定和地球化学特征分析,从矿物岩石、古生物化石及地化特征几方面研究歧口凹陷沙一下亚段湖相白云岩的形成环境、时空展布特征及成因机理。通过储层宏观特征及微观结构的研究,总结了白云岩的储集空间类型,物性特征,裂缝分布规律及控制因素,并进行了有利区带分布预测。通过对研究区白云岩类样品的镜下鉴定,结合X衍射分析、扫描电镜分析,认为研究区白云岩主要发育有微晶白云岩、泥晶白云岩、泥质白云岩、砂质白云岩、灰质白云岩或白云质灰岩五种白云岩类型。通过对取芯井段的岩心深度归位,分析统计不同白云岩类型对应的测井解释,建立了适合研究区白云岩类型识别的GR和AC曲线交汇图版。弄清了白云岩在全区目的层段的分布规律。微晶白云岩和泥晶白云岩主要分布于沙一下亚段的滨1和板4油组的齐家务、周清庄六间房王徐庄及赵家堡和黄骅地区;泥质白云岩主要分布于板4油组的沧州和旧城地区,板3油组的王徐庄地区;灰质白云岩和白云质灰岩主要分布于板3油组的六间房联盟地区,板2油组的齐家务和周清庄地区;砂质白云岩则主要在滨1油组和板3油组的赵家堡地区局限分布。对于东部陆相湖盆古近系的咸化成因一直以来就争议不断,主要有古盐岩风化、湖盆水体蒸发浓缩、火山物质及海侵影响。通过对歧口凹陷沙一下亚段岩样进行各种分析化验,发现其Sr/Ba比、V/Ni比及Th/U比值均指示海水环境,碳、氧稳定同位素测试计算的Z值分布与锶稳定同位素值也主要指示海水与湖水的共同作用的水介质特征;结合薄片观察及扫描电镜分析发现的具指相意义的海绿石、胶磷矿,钙质超微化石等海相性标志,表明歧口凹陷沙一下亚段湖盆的咸化主要受海侵因素影响。海侵不仅为近海湖盆白云岩的形成提供了部分Mg²⁺,更重要的是改变了湖盆水体性质,促进了白云岩化作用。在参考前人对湖相白云岩形成条件及成因机理研究的基础上,本论文通过岩石薄片鉴定和扫描电镜分析、阴极发光、.X-衍射分析、微量元素地球化学等研究方法,综合分析认为研究区白云岩主要有准同生交代白云岩和埋藏成岩白云岩两种成因类型。准同生白云岩主要分布在齐家务和黄骅地区及其以南地区;六间房周清庄王徐庄及其以北地区则主要以埋藏成岩白云岩为主。最后,通过岩心和铸体薄片观察,总结出研究区主要的储集空间类型,以构造缝和溶蚀孔为主,裂缝分布受岩性和构造共同作用。白云岩储层主要为微晶云岩和泥晶云岩。综合分析认为,研究区白云岩储层主要分布于沙一下亚段的滨1和板4油组,以埋藏白云岩分布为主的六间房联盟周清庄和赵家堡地区最为有利,准同生白云岩分布的齐家务地区也是较有利的勘探区带。更多还原

【Abstract】 The origin of dolomite has been one of major research issues in sedimentology field. Based on full investigation of previous associated research results, with basic theories such as carbonate rocks petrology and reservoir geology as a guide, the dissertation carries out a dedicated study into the formation environment, spatial and temporal distribution and formation mechanism of dolomite in the lower part of the Sha-1 formation of Qikou depression from mineral rocks, fossil specimens and geochemical characteristics, etc, by using core, drilling, mud logging and logging data, combined with microscopic identification and geochemical characteristics analysis. Through the study of reservoir macro features and microstructure, the dissertation explores the reservoir space categories, physical properties, fractures distribution rule and controlling factors, and undertakes favorable reservoir areas distribution prediction.Through the microscopic identification of dolomite samples in the study area, and in combination with X diffraction and scanning electron microscopy analysis, it is concluded that the study area comprises mainly 5 types of dolomites, including microcrystalline dolomite, micritic dolomite, argillaceous dolomite, sandy dolomite, and calcite dolomite or dolomite limestone. Then by virtue of the depth homing of coring internal, the author carries out log interpretation analysis and statistics corresponding to different types of dolomites, and establishes suitable GR and AC curve cross-plots for dolomites type identification in the study area. The distribution of the dolomite in the objective intervals of the study area is determined: microcrystalline dolomite and micritic dolomite are mainly in Qi Jiawu, Zhou Qingzhuang-Liu Jianfang-Wang Xuzhuang , Zhao Jiabao and Huang Hua in Bin-1 and Ban-4 oil formations of the lower part of the Sha-1 formation; argillaceous dolomite is mainly distributed in Cangzhou and Jiucheng area of Ban-4 oil formation and Wang Xuzhuang of Ban-3 oil formation; calcite dolomite and dolomite limestone are mainly in Liu Jianfang- Lianmen area of Ban-3 oil formation, and Qi Jiawu and Zhou Qingzhuang of Ban-2 oil formation; and sandy dolomite is mainly in part area of Zhao Jiabao of Bin-1 and Ban-3 oil formations.The salinizing origin of eastern continental facies lake basin in Paleogene has been unsolved issue, with disputes over ancient salt rock weathering, lake basin water evaporation concentration, volcanics and transgression effect. A variety of analysis and tests of rock samples of Sha-1 lower sub member in Qikou depression show that Sr/Ba ratio, V/Ni ratio and Th/U ratios all indicating marine environment, with Z values distribution for carbon and oxygen stable isotope and strontium isotope values indicating aqueous medium features forming under the co-activation of sea water and lake water. The diagnostic glauconite and phosphorite discovered during thin section observation and calcareous nannofossil and other marine facies fossils found through scanning electron microscopy suggest that Sha-1 lower sub-member in Qikou depression was formed due to the transgression, which not only provides part of Mg²⁺ for the formation of offshore lake basin dolomite, but more importantly, changes the nature of the lake basin water so as to promote the dolomitization.In light of the previous studies on the formation conditions and mechanism of lacustrine facies dolomite, using rock thin section identification and scanning electron microscopy analysis, cathodoluminescence, and X-diffraction analysis, trace elements geochemistry and other research methods, the dissertation concludes that penecontemporaneous dolomite and burial diagenetic dolomite dominates the study area, with penecontemporaneous dolomite mainly locating in Qi Jiawu, Huanghua area and its south part, and Liu Janfang-Zhou Qingzhuang-Wang Xuzhuang and its north mainly consisting mainly of burial diagenetic dolomite.Finally, main reservoir spaces of the study area are structural joints and dissolution pores, with fractures distribution formed by the interaction of lithology and structures, through cores and cast thin section observation. The dolomite reservoirs are mainly microcrystalline dolomite and micritic dolomite. Comprehensive analysis shows that the dolomite reservoirs in the study area are mainly distributed in Bin-1 and Ban-4 oil formation of Sha-1 lower sub-member, and Liu Jianfang-Lianmeng-Zhou Qingzhuang and Zhao Jiapuzi area is most favorable where burial dolomite prevails, and Qi Jiawu area with penecontemporaneous dolomite distribution is also fairly favorable exploration area.更多还原