鄂尔多斯盆地中部长8低孔低渗储层成岩作用与成岩烃类充注过程研究

发布时间：2018-04-20 04:17

本文选题：成岩作用 + 孔隙结构　；参考：《西北大学》2015年硕士论文

【摘要】：鄂尔多斯盆地中部的延长探区内上三叠统延长组长8砂岩储层油气显示较好,探明储量大,展现了良好的勘探潜力。本文针对该区长8砂岩储层的矿物组分、物性与孔隙结构特征、成岩作用、油气充注期次及时间等方面的研究薄弱点,利用普通薄片与铸体薄片显微镜下鉴定与定量统计、荧光薄片微束荧光分析、X-射线衍射、电镜扫描、激光拉曼流体包裹体成分分析与均一温度测定等多种分析测试手段,系统研究了长8砂岩储层的岩石学特征、孔隙结构、主要成岩作用类型及成岩演化序列、流体包裹体特征及油气充注期次、成岩-烃类充注过程等内容,以期有助于正确认识和理解成岩作用对砂岩物性的影响、探讨成岩-成藏动力学过程控制的流体-岩石相互作用系统及其时空演变机制,进一步指导油气勘探开发。研究成果揭示,长8砂岩储层以岩屑质长石砂岩为主,总体上成分成熟度低,结构成熟度中等,胶结物主要为碳酸盐胶结物和伊利石黏土矿物。在经历了压实作用、胶结作用、溶蚀作用、交代作用等成岩作用之后,砂岩储层变成了特低孔低渗储层,孔隙度平均为6.65%,渗透率平均为0.24mD。压实作用和胶结作用是储层孔隙度丧失的主要因素,由此造成的平均孔隙度丧失率分别为24.8%和8.9%。因此,压实作用对储层储集物性的破坏程度甚于胶结作用；溶蚀作用产生的粒间溶孔和长石溶孔在一定程度上改善了储层物性,溶蚀作用增加的孔隙平均为3.5%。研究区长8砂岩普遍进入了中成岩A期,期间经历了包括压实作用、胶结作用、三期油气充注作用、二期溶蚀作用等成岩作用过程,其成岩演化序列为：机械压实作用→泥晶方解石-→粘土膜(绿泥石膜Ⅰ)→烃类Ⅰ→石英次生加大Ⅰ→绿泥石膜Ⅱ→伊/蒙混层→溶蚀作用Ⅰ→烃类Ⅱ→石英次生加大Ⅱ→亮晶方解石Ⅰ→高岭石→粒间伊利石、绿泥石胶结→浊沸石→构造裂缝→溶蚀作用Ⅱ→烃类Ⅲ→亮晶方解石Ⅱ。建立在储层成岩作用、流体包裹体特征与油气充注、成岩-烃类充注演化时间序列研究、地层埋藏热史分析基础上的长8砂岩的成岩-烃类充注演化过程综合研究结果表明,长8储层经历过三期油气充注-成岩演化过程：第一期油气充注发生在早成岩阶段A-B期,充注时间为中侏罗世(约169～161Ma,地层埋深1200-1400m),充注规模小,主要分布在绿泥石薄膜保存的原生孔隙中,本期油气充注未捕获与之对应的流体包裹体；第二期油气充注发生早成岩阶段B期的晚侏罗世到早白垩世早期(148-135Ma),地层埋深达到1500～1900m,油气主要分布在颗粒边缘和少量溶蚀孔中,对应捕获流体包裹体显示的峰值温度为70～90℃；第三期烃类充注发生在早白垩世晚期(125.2～105.7Ma),地层埋深达到2300-3100m,规模最大,为最主要的成藏期,油气大量分布在各种溶蚀孔和裂缝中,对应捕获流体包裹体显示的峰值温度为100～120℃,此阶段后晚期亮晶方解石胶结使得岩石变得低孔低渗。
[Abstract]:The upper three superposition of Yanchang Group 8 sandstone reservoir in the middle part of the Ordos Basin shows good oil and gas display, the proven reserves are large, and good exploration potential is shown. In this paper, the weak points of mineral composition, physical property and pore structure characteristics, diagenesis, oil gas filling period and time in the long 8 sandstone reservoir in this area are studied. The lithologic characteristics, pore structure and main diagenesis of long 8 sandstone reservoirs are systematically studied by the identification and quantitative statistics of ordinary thin slices and cast thin slices, microbeam fluorescence analysis, X- ray diffraction, electron microscope scanning, composition analysis of laser Raman fluid inclusions and uniform temperature measurement. The evolution sequence of diagenesis, the characteristics of fluid inclusions and the filling period of oil and gas, the process of diagenesis and hydrocarbon filling, will be helpful to correctly understand and understand the effect of diagenesis on the physical properties of sandstone, and discuss the fluid rock interaction system controlled by the dynamic process of diagenesis and reservoir formation and its spatio-temporal evolution mechanism, and further guide the exploration of oil and gas. The research results reveal that the long 8 sandstone reservoirs are mainly lithic feldspar sandstone, with low maturity and medium maturity, and the cementation is mainly carbonate cementation and illite clay minerals. After the compaction, cementation, dissolution and metasomatism, the sandstone reservoirs become extremely low Kong Di. The porosity of the reservoir is 6.65%, the average permeability is 0.24mD. compaction and cementation is the main factor of porosity loss. The resulting porosity loss rate is 24.8% and 8.9%., respectively. The feldspar dissolution pores have improved the physical properties of the reservoir to a certain extent. The increase of porosity is the average of the 8 sandstone in the 3.5%. research area, which generally entered the A stage of the middle diagenesis. During the period, it experienced the process of compaction, cementation, three phases of oil gas filling and two phases of dissolution, and the evolution sequence of the diagenesis was mechanical compaction. Clay crystal calcite - clay film (chlorite membrane I) - hydrocarbon I - I - quartz secondary enlargement I - I - chlorite membrane II - I / montmorillonite - I - II - quartz secondary increase II to quartz secondary calcite I - Kaolinite - intergranular illite, chlorite cementation, turbid turbid, corrosion - II - III - Bright crystal calcite II. Based on the reservoir diagenesis, fluid inclusion characteristics, oil gas filling, diagenesis and hydrocarbon filling evolution time series, the comprehensive study on the evolution process of diagenesis and hydrocarbon filling of long 8 sandstone based on the thermal history analysis shows that the long 8 reservoir has experienced three stages of oil gas filling and diagenetic evolution process: first The period of oil and gas filling occurred in the A-B period of the early diagenesis stage, and the filling time was middle Jurassic (about 169 ~ 161Ma, buried depth 1200-1400m), and the filling was small, mainly distributed in the primary pores preserved in the chlorite film, and the oil and gas filling in this period did not capture the fluid inclusions corresponding to it, and the second phase of oil and gas filling occurred in the late stage of the early diagenetic stage of the late Jurassic period. From early Cretaceous to early Cretaceous (148-135Ma), the buried depth of the strata reached 1500 ~ 1900m. The oil and gas were mainly distributed in the edge of the particles and a small amount of corrosion holes. The peak temperature corresponding to the trapped fluid inclusions was 70~90. The third hydrocarbon filling occurred in the late Early Cretaceous (125.2 ~ 105.7Ma), the depth of the stratum was 2300-3100m and the largest scale. For the most important period of reservoir formation, oil and gas are widely distributed in various dissolution pores and cracks. The peak temperature of the trapped fluid inclusions is 100~120 C. Later, late bright calcite cementation makes the rock lower and low permeability.

【学位授予单位】：西北大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P618.13

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