塔里木盆地顺北地区中-下奥陶统“断控”缝洞系统划分与形成机制

碳酸盐岩地层普遍发育各类成因机制的非均质性缝洞储层，其孔隙系统的形成演化受岩石的地质演化控制。一般情况下，这类非均质性缝洞储层的形成与地层流体系统中各种不饱和性流体的热化学作用方式和所能带走的物质体积总和有关。但是，塔里木盆地顺北地区发现的“断控”缝洞储层未经历不饱和性流体的溶蚀改造作用，其空间展布明显受到断裂带边界约束，勘探证实可以形成商业价值储层。因此，断裂活动能否发生大规模的物质体积调整，形成完整的缝洞储集系统，需要引起重视。通过应用三维地震、钻井异常工况、测井、元素录井、压恢试井、干扰试井和生产动态资料等，综合表征“断控”储层特征，反演“断控”缝洞单元和储集系统。针对走滑断裂活动过程中的岩石物理特性、构造增容机理和流体改造机制，开展了脆性岩层应变方式、断层封闭性控制因素、水-岩作用方式等研究，提出断裂带内部受岩体错动、破碎及力学-热化学作用而发生的物质体积调整是顺北地区“断控”缝洞储层形成的主导因素，其孔隙系统的形成、演化与断裂活动关系密切。当“断控”缝洞系统形成、演化过程中无法忽视流体影响时，可依据流体性质和作用方式等，细分出“岩溶型”和“热溶型”亚类，作为“断控”储层概念的理论衍生。

Division and formation mechanism of fault-controlled fracture-vug system of the Middle-to-Lower Ordovician,Shunbei area,Tarim Basin

Heterogeneous fractured-vuggy reservoirs of diverse genetic mechanisms are widely developed in carbonate strata， and the pore generation and evolution of diverse types within is related to the geological evolution of rocks. Generally， the formation of heterogeneous fractured-vuggy reservoirs is associated with thermochemical action mode of various unsaturated fluids in the formation and the total volume of materials that can be carried away. However， the fault-controlled fractured-vuggy reservoirs in Shunbei area， Tarim Basin， are not subjected to dissolution modification of unsaturated fluid， and feature a space distribution mainly constrained by fault zone boundaries. Exploration experiences have suggested that those reservoir spaces can be of hydrocarbon reservoirs with commercial value. What we have to pay attention to lies in whether a reservoir system of fracture-vug type can be formed under large-scale volume adjustment of materials by fault activities. An integration of 3D seismic interpretation， analysis of abnormal drilling conditions， well logs， element logging， pressure buildup test， interference test， and production performance data， is applied to comprehensively characterize the fault-controlled reservoirs， with their fractured-vuggy units and reservoir system inverted. The strain mode of brittle strata， factors controlling fault sealing， and water-rock interaction mode are studied according to the rock physical characteristics， structural compatibilization mechanism， and fluid modification mechanism during the strike-slip fault activity. It is proposed that the material volume variation resulted from rock dislocation， damage， and mechanical-thermochemical action in the fault zone， is a factor determining the formation of fault-controlled fractured-vuggy reservoirs in Shunbei area， whose pore system formation and evolution is closely related to fault activities. As theoretical derivation， the fault-controlled reservoirs can be subdivided into two types given the property and action mode of fluids， that is， the reservoir of karst type and of hydrothermal dissolution type， if being ignorable effects in the process of formation and evolution of their fracture-vug system.