富硅质碳酸盐岩储层地球化学特征及成因——以四川盆地泰来地区茅口组为例

Geochemical characteristics and origin of silicon?鄄rich carbonate reservoirs: a case study of Maokou Formation in Tailai area, Sichuan Basin

张军涛 武重阳 杨佳奇 何治亮 潘磊 唐德海 杨天博 韩月卿 李让彬

中国石化石油勘探开发研究院，北京 100083 中国石化深部地质与资源重点实验室，北京 100083 中国地质大学（北京）能源学院，北京 100083 中国石油化工股份有限公司，北京 100728 中国石化勘探分公司，四川 成都 610041

Petroleum Exploration and Production Research Institute, SINOPEC, Beijing 100083, China Key Laboratory of Geology and Resource in Deep Stratum, SINOPEC, Beijing 100083, China School of Energy Resources, China University of Geosciences, Beijing 100083, China SINOPEC, Beijing 100728, China Exploration Company, SINOPEC, Chengdu 610041, China

四川盆地二叠系热液白云岩备受关注，但缺乏对于热液矿物和热液流体贡献的深刻认识，对泰来地区富硅质碳酸盐岩储层的研究也相对较少。该研究以四川盆地泰来地区茅三段富硅质碳酸盐岩储层为例，根据碳氧锶同位素、主微量及其他稀土元素组成，结合岩石学特征，对热液矿物（如鞍形白云石、硅质等）进行系统研究。研究结果表明：鞍形白云石成因为热液流体直接沉淀，碳酸盐充填矿物流体来源为海水和热液的混合流体，以海水为主。岩浆作用在研究区内不仅通过其加热盆地，促进鞍形白云石和其他热液矿物的沉淀，而且提供了1%~5%、甚至更多的现代黑烟囱流体（热液流体）的等量物质对充填物的地球化学特征进行重印。热液流体（包括白云化和硅质流体）活动期间促进裂缝的发育，是改善储层最重要的因素；热液矿物充填裂缝导致储层破坏。研究区有效储层的勘探方向应为高能滩相热液改造弱或少泥质含量、易于产生破碎裂缝的区域。

The Permian hydrothermal dolomite in the Sichuan Basin receives much attention. However, there were lack of deep understanding of the contribution of hydrothermal minerals and hydrothermal fluids, and relatively few studies on silicon?鄄rich carbonate reservoirs in Tailai area. Taking the silicon?鄄rich carbonate reservoir in the third Member of the Maokou Formation inTailai area, Sichuan Basin as an example, according to characteristics of carbon, oxygen, and strontium isotopes, major and trace elements, and rare earth elements, combined with petrological characteristics, hydrothermal minerals such as saddle dolomite, silicalite and so on were studied systematically. The results showed that saddle dolomite was formed by direct precipitation of hydrothermal fluids, and the fluid origin of carbonate filling minerals was the mixed fluid of seawater and hydrothermal fluid, mainly seawater. Magmatism in the study area not only promoted precipitation of saddle dolomite and other hydrothermal minerals by heating the basin, but also provided 1%￣5% and even more modern black chimney fluid equivalents to reprint geochemical characteristics of the fillings. The hydrothermal fluids (including dolomitized and siliceous fluids) promoted the development of fractures, which was the most important factor to improve the reservoir. The filling of fractures by hydrothermal minerals led to the destruction of the reservoir. The exploration direction of the effective reservoir in the study area is the area where the high?鄄energy beach facies was weakly reformed by the hydrothermal fluid or where the argillaceous content was low and proved to fracture.

10.6056/dkyqt202305011