准噶尔盆地西北地区断层内流体活动过程及对断层启闭性的影响

Fluid activity in faults in the northwestern Junggar Basin and its influence on fault opening and sealing

赵乐强 贾凡建 曹剑 刘慧 边雪梅 高剑雄

Zhao Leqiang Jia Fanjian Cao Jian Liu Hui Bian Xuemei Gao Jianxiong

中国石化 胜利油田分公司, 山东 东营 257000 2. 南京大学 地球科学与工程学院, 南京 210023

SINOPEC Shengli Oilfield Company, Dongying, Shandong 257000, China 2. School of Earth and Engineering, Nanjing University, Nanjing, Jiangsu 210023, China

利用野外、钻井、测井和地球化学分析等资料，对准噶尔盆地西北地区断层内流体活动过程及对断层启闭性的影响进行了研究。准西北地区断层发生过4期流体活动：断层形成初期，滑动破碎带受力最为集中，破碎较为严重，一期幔源流体首先进入滑动破碎带，并不断析出矿物充填其中，物性变差；二期幔源流体在滑动破碎带物性较好的部位穿插运移，胶结形成的矿物与一期形成的矿物脉体将滑动破碎带封堵；三期盆源流体主要在物性较好的主动盘裂缝带内运移，少部分进入被动盘诱导裂缝带；四期大气降水在断层物性较好的主动盘诱导裂缝带和被动盘诱导裂缝带内活动，初期主要以溶蚀作用为主，后期胶结作用较为强烈。由于第三期盆源流体活动期间，往往也是盆内大规模油气排烃时期，流体中往往含有大量油气，因此油气的运移主要在主动盘诱导裂缝带内进行，其次为被动盘诱导裂缝带，滑动破碎带实际上起封闭作用，不输导油气。

The fluid flow process and its effect on fault opening and sealing in the northwestern Junggar Basin were studied based on field outcrop, drilling, logging and geochemical analyses. Four stages of fluid activities have occurred. During the early period of fault formation, the sliding fracture zone got the most concentrated force and was extensively crushed. The first phase of mantle-derived fluid entered the sliding fracture zone and continuously precipitated minerals, which made physical properties become worse. The second phase of mantle-derived fluid migrated in the parts where physical properties were relatively better in the sliding fractured zone. The cemented minerals and the mineral veins formed in the first phase closed the sliding fracture zone. The third phase of fluid from the basin mainly migrated in the fracture zone of the active wall where physical properties were relatively better, and a small part entered the induced fracture zone of the passive wall. In the fourth phase, atmospheric precipitation entered the induced fracture zones of the active wall and the passive wall where physical properties were relatively better. In the initial stage, dissolution was essential, while in the late stage cementation was stronger. When the fluid from the basin was active in the third phase, large-scale hydrocarbon was expelled from the basin. As a result, the fluid often contained large amounts of oil and gas. Hydrocarbon mainly migrated in the induced fracture zone of the active wall, and secondly in the induced fracture zone of the passive wall. The sliding fracture zone played the role of closure not transport.

国家科技重大专项“准噶尔盆地碎屑岩层系油气富集规律与勘探评价”（2016ZX05002-002）和中国石化科技攻关项目“准噶尔盆地压扭性断裂体系控藏作用研究”（P14066）联合资助。

https://doi.org/10.11781/sysydz201704461