东营凹陷中央隆起带烃类流体活动在成岩作用上的响应

Response of Diagenesis to Hydrocarbon Fluid Flow in Central Uplift Belt of Dongying Depression

为探讨成岩作用对烃类流体活动的响应,利用显微观察、包裹体测温、扫描电镜、阴极发光等研究方法,系统地研究了东营凹陷中央隆起带沙三段自生矿物形成与烃类流体活动的相关性。研究表明:研究区沙三段储层的成岩序列为:第一期石英次生加大边→第一期碳酸盐胶结物(黄铁矿)→绿泥石薄膜→第二期碳酸盐胶结物→第二期石英次生加大边(第一期高岭石)→第三期碳酸盐胶结物→第三期石英次生加大边(第二期高岭石)→第四期含铁碳酸盐胶结物(黄铁矿)。第一期油气充注发生于第二期碳酸盐胶结物形成的后期,第二、三期油气充注发生于第三期碳酸盐胶结物形成的中后期,第四期碳酸盐胶结物的形成标志大规模油气充注时期的结束。烃类流体活动对研究区的自生高岭石、含铁碳酸盐矿物(第四期碳酸盐胶结物)、黄铁矿等3类自生矿物的形成过程产生重要影响。砂岩储层中,第二、三期碳酸盐胶结物的港湾状溶蚀现象、高岭石大量发育、第四期碳酸盐胶结物和黄铁矿的共生组合等成岩现象可作为微观上识别烃类流体活动的标志。含油性较好的层段,烃类流体活动可导致碳酸盐胶结物产生大规模的溶蚀作用,并促使长石溶蚀产生大量高岭石,砂泥岩界面处可见黄铁矿与含铁碳酸盐胶结物共生;而含油性差及不含油的层段,由于缺少烃类流体提供的大量有机酸,高岭石发育较少,早期碳酸盐胶结物保存较好。

In order to find out the response of diagenesis to hydrocarbon fluid flowin the Third Member of Shahejie Formation in central uplift belt of Dongying depression,the relationshipbetween the formation of authigenic minerals and hydrocarbon fluids flow were analyzed based on the results of microscopic observation, inclusion thermometry, scanning electron microscope and cathode luminescence.the diagenetic sequence is：the first period of quartz overgrowth → the first period of carbonate cements（pyrite particles）→a layer of chlorite film→the second period of carbonate cements→the second period of quartz overgrowth（the first period of kaolinite）→ the third period of carbonate cements→ the third period of quartz overgrowth（the second period of kaolinite）→the fourth period of ferric carbonate cements（pyrite particles）.The first hydrocarbon filling occurred duringthe later stage of the second period of carbonate cements formation.The second and third hydrocarbon filling occurred duringthe mid-to-late stage of the third period of carbonate cements formation.The formation of the fourth period of carbonate cements representsthe end of large-scale hydrocarbon filling.Hydrocarbon fluid has great impact on the formation of three types of authigenic minerals in the study area,including authigenic kaolinite,ferric carbonate minerals and pyrite.In the sandstone reservoir,the activity of hydrocarbon fluid can be identified by various diagenetic phenomena,such as embayed corrosion of the second and the third period of carbonate cements,large growth of kaolinite,and paragenetic association of the fourth period of carbonate cements and the pyrite. In the sandstone strata with high oil saturation,hydrocarbon fluid may lead to large-scale corrosion of carbonate cements and the corrosion of feldspar, which causeagreat formationof kaolinite. In addition, paragenetic association of ferric carbonate cements and pyrite can be observed at the interface of sandstone and mudstone.However,in the strata with low oil saturation or oil-free,due to lacking of organic acid provided by hydrocarbon fluid,kaolinite is less developed,and the early period of carbonate cements is well preserved.