塔里木盆地顺北地区超深碳酸盐岩断溶体发育特征与形成机制

Development characteristics and formation mechanism of ultra-deep carbonate fault-dissolution body in Shunbei area, Tarim Basin

吕海涛 韩俊 张继标 刘永立 李映涛

LÜ Haitao HAN Jun ZHANG Jibiao LIU Yongli LI Yingtao

中国石化 西北油田分公司, 乌鲁木齐 830011 中国石化 石油勘探开发研究院, 北京 100083

SINOPEC Northwest Branch Company, Urumqi, Xinjiang 830011, China SINOPEC Petroleum Exploration and Production Research Institute, Beijing 100083, China

走滑断裂带作为一个空间地质体，具备物理-化学机制下的增容作用，可以在断裂带内部形成独特的缝洞系统及伴生孔洞、孔隙空间，塔里木盆地顺北地区发育超深碳酸盐岩断溶体相关的缝洞系统，其储集体与断裂带活动关系密切。以顺北地区走滑断裂带为研究对象，综合近年来对走滑断裂带解析及勘探实践认识，分析走滑断裂带内部结构，探讨断溶体（储集体）发育特征及成因。其断溶体空间展布明显受到走滑断裂带边界的约束，储集体的外在轮廓主要受断裂带控制，宽度相对窄，纵向发育深度大。其储集空间主要由多期走滑构造破裂作用与断裂带内物质体积调整形成的“空腔”型洞穴和缝网系统组成，并经历了多类型流体的溶蚀-胶结作用叠加改造，形成了在断裂带内沿着断层发育的裂缝-洞穴系统，并伴生发育溶蚀孔洞与各类孔隙空间，导致断溶体内部储集体结构复杂化。根据断裂带内部流体参与程度和流体类型不同，可以细分出3种成因机制的端元模型：断容型、岩溶型和热溶型。断溶体的形成机制可以是其中的一种，也可以是2种或3种类型的组合。断溶体与岩溶缝洞储层最本质的差异在于，前者缝洞系统的构成和储集规模的形成与断裂活动关系密切，后者则主要取决于水-岩作用的方式和所能带走的物质体积总和。

As a spatial geological body, a strike-slip fault zone has a physically and chemically controlled compart- mentalization effect, which can form a unique fracture-cavity system with associated pore spaces inside the fault zone. A fracture-cavity system related to ultra-deep carbonate "fault-dissolution body" developed in Shunbei area of the Tarim Basin, and its "fault-dissolution body" reservoir is closely related to fault activities. The Shunbei strike-slip fault zone was studied with previous analyses and practices. The inner structure of the strike -slip fault zone was discussed, and the origin and characteristics of "fault-dissolution body" were analyzed. The spatial distribution of the "fault-dissolution body" reservoir is constrained by the boundary of the strike-slip fault. The external contour of the reservoir is mainly controlled by the fault zone, and the width is narrow while the depth is large. The reservoir space is mainly composed of "cavity" type caverns and a seam network formed by multi-stage structural rupture, and has undergone erosion and cementation via multiple types of fluids, forming dissolution holes and various pore spaces along the fracture system, and it leads to the complexity of the internal reservoir structure of fault- dissolution body. According to the dynamic changes of fluid participation and fluid properties in the fault zone, three genetic mechanisms can be identified: fault-capacity, karst and hydrothermal fluid erosion. The formation mechanism of the "fault-dissolution body" may be one of them, or a combination of two or three types. The most essential difference between "fault-dissolution body" and karst cave reservoir is that the composition of the former fracture-cavity system and the formation of reservoir scale are closely related to the fault activity, while the latter depends mainly on the water-rock interaction and the total matter volume removed.

国家科技重大专项 2017ZX05005-002;中国石化科技部项目 P16112

https://doi.org/10.11781/sysydz202101014