川东北元坝地区中三叠统雷口坡组热液流体及储层改造作用

The Middle Triassic Leikoupo Formation in Yuanba area, Northeast Sichuan basin was demonstrated to have a superior prospect for hydrocarbon exploration. In preliminary researches, we noted that abundant hydrothermal minerals presented in this Formation. Therefore, this project plans to take hydrothermal fluid activity and its effect on reservoir development as the core of research. Based on the typical well core and outcrop section investigation and sampling, thin section cathodoluminescence and SEM observation, carbon/oxygen/strontium isotopic measurement, major, trace and rare earth element test, electronic probe, and X-ray diffraction detection, and fluid inclusion analysis (including component and homogenization/freezing temperatures analysis), we will study characteristics of petrology, mineralogy and geochemistry of the hydrothermal minerals. Furthermore, evidence of hydrothermal activities and iconic hydrothermal minerals and their combination should be confirmed. We can divided hydrothermalism period time, tracer hydrothermal origin, inversion of fluid properties. Also, progress of interaction between hydrothermal fluid and carbonate rocks and mechanism of deferent hydrothermal fluids modify the reservoir will be confirmed. Carrying out of this project is not only benefit to the recognition of hydrothermal activities and its influence on carbonate rocks deeply but also in favor of providing practical guidance to the oil and gas exploration in the study area.

川东北元坝地区中三叠统雷口坡组具有很好的油气显示，前期研究注意到其发育丰富的热液活动迹象。本项目拟围绕热液流体活动及其对储层改造这一核心内容，选择典型钻井岩心及野外剖面为研究对象，通过现场岩心和野外剖面观察及采样、室内薄片鉴定、碳氧同位素、锶同位素、硫同位素、微量和常量元素、稀土元素、电子探针、阴极发光、扫描电镜、X衍射和包裹体（成分、均一和冰点温度）分析等研究手段，剖析雷口坡组热液充填矿物的岩石学、矿物学及地球化学特征，在此基础上确立热液成因证据和标志性热液矿物及组合，划分热液作用期次，示踪热液来源，反演流体性质，揭示热液流体与碳酸盐岩的水岩相互作用过程，查明热液流体对储层的改造机制。本项目的开展不仅有利于深化对碳酸盐岩地层中热液活动及其影响的认识，也可为研究区油气勘探提供实际指导。

川东北元坝地区中三叠统雷口坡组具有很好的油气显示，前期研究注意到其发育丰富的热液活动迹象。本项目拟围绕热液流体活动及其对储层改造这一核心内容，选择典型钻井岩心为研究对象，通过现场岩心观察及采样、室内薄片鉴定、碳氧同位素、锶同位素、电子探针、阴极发光、扫描电镜、X射线能谱和包裹体（均一温度）等研究手段，剖析雷口坡组热液充填矿物的岩石学、矿物学及地球化学特征，我们限定了裂缝充填物沉淀流体性质、来源、演化。白云石的气液两相包裹体的均一化温度范围为112~183℃。结合氧同位素数据表明沉淀流体的δ18O值范围为-5‰~7‰(SMOW)。证明川东北元坝地区中三叠统雷口坡组四段裂缝中普遍存在的白云石是高温、高盐度卤水活动的结果。研究结果发现这种高温浓卤水应来自于地层封闭热卤水和深部热流体混合，并在成岩阶段富集了锶元素。在此基础上，揭示热液流体与碳酸盐岩的水岩相互作用过程，认为热液流体造成的溶蚀及其产生的热液白云石化作用对储层孔隙的形成起到重要作用。本项目的开展不仅有利于深化对碳酸盐岩地层中热液活动的认识，也可为研究区油气勘探提供实际指导。