【作者】 付广；

【导师】 吕延防；

【作者基本信息】 大庆石油学院 ， 油气田地质工程， 2006， 博士

【摘要】 在不同相态天然气运移机制研究的基础上，全面、系统地对泥质岩盖层对各种相态天然气封闭机理进行了深入研究，认为泥质岩盖层对游离相天然气主要是毛细管封闭，异常孔隙流体压力可以起到间接封闭作用。对水溶相天然气的封闭主要是泥质岩的吸附阻力作用，异常孔隙流体压力也会起到重要作用。对扩散天然气主要是泥质岩盖层的抑制浓度封闭和替代浓度封闭。通过排替压力、异常孔隙流体压力、吸附阻力、异常含气浓度和生气强度对泥质岩盖层对游离相、水溶相和扩散相天然气的封闭能力进行了全面系统研究。排替压力是评价泥质岩盖层毛细管封闭能力的最根本参数，它可以通过实验获得，也可以在实测的基础上，利用声波时差资料和地震层速度资料来求取。异常孔隙流体压力也是影响泥质岩盖层封闭游离相天然气的一个重要参数，可以利用声波时差资料求取，也可以利用地震层速度资料来求取。异常含气浓度是评价泥质岩盖层抑制浓度封闭能力的主要指标，可以利用其所处的温压条件计算得到。生气强度是泥质岩盖层自身生烃特征的反映，可以作为其替代浓度封闭作用的评价指标，可利用源岩生烃研究结果获得。压实成岩程度在一定程度上反映了泥质岩盖层对水溶相天然气吸附能力的强弱，可以作为其对水溶相天然气封闭作用的评价指标，可利用泥质岩压实成岩作用的研究成果获得。从盆地或凹陷构造演化、沉积环境及压实成岩程度几个方面阐述了泥质岩盖层形成的有利条件。盆地内的凹陷区是泥质岩盖层形成发育的最有利地区。盆地内相对大规模下沉的最大水进期是泥质岩盖层发育的有利时期。浅海、半深湖~深湖和开阔的潮坪及泻湖相是泥质岩盖层形成发育的有利环境，晚成岩阶段的A亚期是泥质岩盖层封闭能力最强时期。在泥质岩盖层对各种相态天然气封闭机理及形成条件研究基础上，对其封闭能力的演化及演化阶段进行了研究。毛细管封闭是泥质岩盖层普遍存在的封气机理，它一经沉积便会存在，且随埋深增加封闭能力逐渐增强。异常孔隙流体压力只能存在于欠压实的泥质岩盖层中，且只能存在于泥质岩盖层压实成岩演化过程中的特定阶段。抑制浓度封闭和替代浓渡封闭也只能存在于具生烃能力的泥质岩盖层中，抑制浓度封闭与异常孔隙流体压力一样，也只能存在于泥质岩盖层压实成岩演化的特定阶段。替代浓度封闭形成于其开始生排气期起，之后随演化程度增高，封闭能力逐渐增强。利用排替压力与埋深之间的函数关系、异常孔隙流体压力与声波时差之间的函数关系和异常含气浓度与温压之间的函数关系，建立了一套泥质岩盖层古排替压力、古异常孔隙流体压力和古异常含气浓度的恢复方法。利用改进后的达西定律，在综合泥质岩盖层宏观发育特征及微观封闭能力的基础上，通过定义和求取CSFI和CSWI指数，分别建立了泥质岩盖层对游离相天然气和水溶相天然气封闭能力的综合定量评价方法。利用改进后的费克定律，在综合泥质岩盖层宏观发育特征及微观封闭能力的基础上，通过定义和求取CSDI指数，建立了泥质岩盖层对扩散相天然气封闭能力的综合定量评价方法。从泥质岩盖层与源岩时空匹配关系，对其在天然气成藏与分布中的作用进行了深入研究，认为盖源分布空间匹配关系控制着天然气在空间上的分布和富集数量，盖源质量空间匹配关系控制着天然气的富集区域，盖源时间匹配关系控制着天然气聚集与保存的数量，盖层空间发育部位控制不同类型圈闭的形成。更多还原

【Abstract】 Based on the study of migration mechanisms of gas in different phases, the seal mechanisms of mudstone caprocks to gas in each phase were overally and systemly studied. Capillary seal was considered to be the main seal mechanism of mudstone caprocks to gas in free phase. Abnormal pore fluid pressure can play an in direct role in sealing gas in free phase, Absorption was considered to be the main seal mechanisms of mudstone caprocks to gas in water-soluble phase. Abnormal pore fluid pressure can also play an important role in sealing gas in water-soluble phase. Restraining and replacing concentration seal was considered to be the main seal mechanisms of mudstone caprocks to gas in diffusion phase. By displacement pressure, abnormal pore flow pressure, absorption force, abnormal gas-bearing concentration and generation gas intensity. The seal ability of mudstone caprock to gas in each phase was overly and systemly studied. Displacement pressure was basic parameter evaluating the capillary seal ability of mudstone caprocks, it can be gotten by experiment, and be gotten by the data of interval transit-time and seismic velocity in the basic of experiment. Abnormal pore fluid pressure is an important factor influencing seal ability of mudstone caprock to gas in free phase. It can be gotten by the data of interval transit-time or by the data of seismic velocity. Abnormal gas-bearing concentration was considered to be the main parameter evaluating the restraining concentration seal ability of mudstone caprocks, it can be gotten by the conditions of temperature and pressure. Gas-expulsion intensity can reflect the hydrocarbon generation characteristics of mudstone caprocks, it can be used as a parameter evaluating the replacing concentration seal ability of mudstone caprock, it can be gotten by the research results of generation hydrocarbon of gas source rocks. Compaction diagenesis stages can reflect the seal ability of mudstone caprock to gas in water-soluble phase, it can be gotten by the research results of diagenesis of mudstone. From structure and structural evolution, sedimentary environment and compaction diagenesis. The favorable formation conditions of mudstone caprock was discussed. The sags of basin were considered to be the most favorable areas of formation and development of mudstone caprocks. The maximum water invasion period of relatively submerged with a great scale in a basin was considered to be the most favorable period of formation and development of mudstone caprocks. Shallow-sea facies, semideep lacustrine and deep lacustrine facies and broad tidal flat and lagoon facies were considered to be the most favorable sedimentary environments of formation and development of mudstone caprocks. A swbage of late diagenesis was considered to be the strongest stage of seal ability of mudstone caprocks. Based on the study of seal mechanism of mudstone caprock to gas in each phase and formation conditions, the evolution and evolution stage of seal ability of seal ability of mudstone caprock was studied. Capillary seal is generally the seal mechanism to gas in free phase, As soon as mudstone caprocks deposited, their seals to gas were formed. With the increase of depth, the capillary seal ability of mudstone caprocks increases. Abnormal pore fluid pressure can only exist in uncompacted mudstone caprocks, and in special stage of their diagenesis evolution.Restraining concentration seal and replacing concentration seal can only exist in the mudstone caprocks with generation hydrocarbon ability. As abnormal pore fluid pressure, restraining concentration seal can only exist in the special stage of their diagenesis evolution. Replacing concentration seal of mudstone caprocks formed when they began to generate gas. With the increase of evolution degree of organic matter, the replacing concentration seal ability increases. Utilizing the functional relation between displace and depth, the functional relation between abnormal pore fluid pressure and interval transit-time and the functional relation among abnormal gas-bearing concentration and temperature, pressure, the recovering methods of ancient displacement pressure, ancient abnormal pore fluid pressure and ancient abnormal gas-bearing concentration was established. Using the corrected Darcy’s law, based on the comprehension of development characteristics and seal ability, a method evaluating comprehensively and quantitatively the seal ability of mudstone caprocks to gas in free phase and gas in water-soluble phase was established through defining and calculationg CSFI and CSWI indexes. Using the corrected Fick’s law, based on the comprehension of development characteristics and seal ability,a method evaluating comprehensively and quantitatively the seal ability of mudstone caprocks to gas in diffusion phase was established through defining and calculationg CSDI index. From the matching relation of time and apace between mudstone caprock and sourcerock, the role of mudstone caprock in gas accumulation and distribution was deeply studied. The space distribution matching relation between caprock and sourcerock controls the distribution and accumulation of gas. The space quality matching relation between caprock and sourcerock controls the accumulation places of gas. The time matching relation between caprock and sourcerock controls the accumulation and preservation amount of gas. The space development places of caprocks controls the formation of different types of traps.更多还原