歧口凹陷滨海断裂带热流体活动及其对油气成藏的影响  

Hydrothermal fluid flow and its influence on the hydrocarbon migration and accumulation along Binhai fault in Qikou sag,Bohai Bay Basin

作　　者：龙华山[1] 向才富[2,3] 牛嘉玉[1] 魏立春[2,3] 

机构地区：[1]中国石油勘探开发研究院,北京100083 [2]中国石油大学油气资源与探测国家重点实验室,北京102249 [3]中国石油大学盆地与油藏研究中心,北京102249

出　　处：《石油学报》2014年第4期673-684,共12页Acta Petrolei Sinica

基　　金：国家重大科技专项(2011ZX05006-005;2011ZX05006-006);自然科学基金项目(No.40872097;No.41272161)资助

摘　　要：热流体能够影响沉积盆地内物质组分的重新分配,如矿物的溶解和油气相态的变化,以及输导系统的热异常,通常沿断裂分布。滨海断裂带为控制烃源岩展布的断裂之一,同时也是流体热异常活动的场所。利用有机地球化学、流体包裹体、气体地球化学、成岩矿物及地层水化学特征等对研究区内流体的热活动进行了研究,为油气沿断裂发生运移和聚集提供了证据,进一步指明了油气勘探的有利方向。热流体沿断裂上涌发生热对流对局部温度场的改变体现在以下几个方面:①镜质体反射率异常反映局部烃源岩受局部温度场的变化发生热演化异常;②成岩期形成的流体包裹体均一温度大于其最大埋深时的温度;③黏土矿物出现同一深度段多类型和同一类型多层段的演化异常;④储层碎屑矿物颗粒的热蚀变。热流体对物质场的改变主要体现在以下几个方面:①热流体带来了深部幔源的无机CO_2于浅层富集成藏;②大量高于卤水矿化度的深部流体渗入发生流体-岩石相互作用,导致储层中存在高矿化度的地层水;③储层早成岩期胶结于孔隙的碳酸盐类等矿物溶蚀形成多个次生孔隙带,进一步证实了水-岩相互作用,次生孔隙的发育来源于碳酸盐类矿物的溶解和重新分布,在一定程度上控制储层的物性;④热流体携带的大量物质发生流体-岩石相互作用导致靠近断裂带的岩石中所含微量元素异常。上述证据均指示了烃类流体能够沿断裂和渗透性砂岩储层发生运移,并可能聚集成藏形成大油气田。In sedimentary basin, hydrothermal fluid flow can affect the redistribution of materials （e. g. , minerals dissolve in fluid and hydrocarbon dissolved in a basin） and the localized thermal anomaly along the pathway systems （most often faults）. Binhai fault is one of the main boundary faults that controls the source rock distribution in Qikou sag, Bohai Bay Basin, which provides a space for flow anomalies of hydrothermal fluid. The investigation of hydrothermal fluid flow in Binhai fault bases on geochemical characteris- tics of organic materials, fluid inclusions, natural gases, diagenetic minerals, and formation water. Evidences for hydrocarbon migration and accumulation along the fault were obtained, with which a favorable direction for hydrocarbon exploration was pointed out. Hydrothermal fluid flow along the fault has created the abnormal high temperature field near the fault. Changes in local temper- ature field related to hydrothermal fluid upwelling along the fault were illustrated by the following evidences： （1） Abnormal vitrinite reflectance indicates abnormal thermal evolution of local source rocks; （2） Fluid inclusions with higher homogenization temperature than that formed at the maximal burial depth of the basin; （3） Clay minerals experienced abnormal evolution, with multi-types in the same depth segment and the same type in multi-segments; （4） Thermal alterations occurred in clastie mineral particles of the reser- voirs. Changes in the material field caused by hydrothermal fluid flow were illustrated by the following evidences： （1）Inorganic CO2 originating from deep mantle and brought upward by hydrothermal fluid flow was enriched and accumulated in shallow; （2） Substantial high-salinity deep fluids penetrated and reacted with source rocks, leading to the accumulation of high-salinity formation water in reservoirs; （3） Multiple segments of secondary porosity zone were developed vertically, further demonstrating the occurrence of waterrock interactions. Seconda

关 键 词：热流体活动 热效应 油气运移与聚集 歧口凹陷 渤海湾盆地 

分 类 号：TE122.12[石油与天然气工程—油气勘探]