ISSN 1000-3665 CN 11-2202/P

    水动力条件对东营凹陷气藏的制约及对CO2封存靶区的启示

    Constraints of hydrodynamic conditions on gas reservoirs in Dongying depression and its enlightenment to CO2 storage target area

    • 摘要: 东营凹陷及周边大量的天然气藏预示着这些区域具有良好的CO2地质封存条件。为了优选出东营凹陷及周边适宜CO2封存的靶区,通过收集资料与盆地流场综合分析,总结归纳了东营凹陷及周边埋深为500~1500 m的天然气成藏的主控因素、赋存模式,以及东营凹陷地下流体动力场对天然气藏形成的制约作用。研究结果显示:(1)按照地下流体运动特征与方式,天然气藏形成的输导方式可划分为侧向型输导体系与垂向型输导体系,侧向型主要分布在凹陷边缘高凸起带,垂向型主要分布在盆内凹陷区。(2)压实流是凹陷中心的深部气源向上运移的主要驱动力,一部分深源气体自凹陷中心向凹陷边缘产生较长距离的运动,在凹陷边缘的高凸起部位压实流与重力流的接合区形成封闭的水动力圈闭,形成侧向型天然气藏;另一部分深源气体在压实流驱动下,沿高孔渗断裂带垂向运移进入顶部的圈闭中聚集成藏。由于断层错断导致的岩性圈闭比较发育,与水动力圈闭一起构成气体的有效圈闭,形成垂向型天然气藏。(3)东营凹陷CO2封存最有利靶区主要位于凹陷西、北方向的青城凸起、林樊家凸起、滨县凸起、陈家庄凸起、广饶凸起等高凸起及其周边;东部的广饶凸起、青坨子凸起等凸起及凹陷区的垂向断裂发育区为CO2封存较有利靶区。研究认识对我国东部沉积盆地高碳排放区CO2地质封存场地优选具有参考意义。

       

      Abstract: A large number of natural gas reservoirs in Dongying depression and its surrounding areas indicate that there are good conditions for CO2 geological storage in these areas. To optimize the target area suitable for CO2 storage, through data collection and comprehensive analysis of Dongying basin flow field, this study summarized the main controlling factors and occurrence modes of natural gas accumulation in Dongying depression and its surrounding areas with a buried depth of 500-1500 m, and analyzed the restrictive effect of underground hydrodynamic field on the formation of natural gas reservoirs. The results show the migration pathways of shallow gas reservoirs can be divided into lateral migration pathways and vertical migration pathways based on the characteristics and modes of underground fluid movement. The lateral type is mainly distributed in the high uplift belt at the edge of the depression, and the vertical type is mainly distributed in the depression area in the basin. Compaction flow is the main driving force for the upward migration of the deep gas source in the center of the depression. A part of the deep gas moves for a long distance from the center of the depression to the edge of the depression, forming a closed hydrodynamic trap and a lateral shallow gas reservoir at the junction of compaction flow and gravity flow in the high convex part of the edge of the depression. The other part of deep gas, driven by compaction flow, migrates vertically along the high porosity and permeability fault zone and accumulates in the trap at the top. Lithologic traps caused by fault dislocation are relatively developed, which together with hydrodynamic traps form an effective trap of gas and form a vertical shallow gas reservoir. The most favorable target area for CO2 storage in the shallow part (500-1500 m) of Dongying depression is mainly located in the west and north direction of the depression, such as Gaoqing Uplift, Linfanjia Uplift, Binxian Uplift, Chenjiazhuang Uplift, Guangrao Uplift, and their surrounding areas. The vertical fault development areas of Guangrao uplift, Qingtuozi uplift, and other depressions in the east are favorable targets for CO2 storage in the shallows.

       

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