岩心中的天然缝与诱导缝的识别与分析——以鄂尔多斯盆地延长组岩心裂缝为例

由于取心成本昂贵, 从岩心中获得天然缝、诱导缝和其他构造特征的准确信息显得尤为重要。岩心裂缝识别中的一项重要任务是判识天然缝和诱导缝。文中综合论述了天然缝和诱导缝的物理特征, 重点分析了天然缝形态及发育过程和诱导缝的多种成因模式, 并以鄂尔多斯盆地延长组岩心中裂缝为例进行分析。文中引用了国外对裂缝研究常用的专业术语, 指出裂缝面形态结构是追踪模式Ⅰ裂缝(节理)从扩展初始点到终止处的运动学的关键, 这在岩心裂缝和露头裂缝分析中是非常有用的。

Indentification and analysis of natural fracture and induced fracture in core: A case study of core fracture of Yanchang Formation in Ordos Basin

Although oriented and unoriented core provides the best opportunities for direct observation of fracture characteristics in subsurface reservoir rock, cost often limits its availability. Such restricted availability of core makes the accuracy of the information gained from such cores all the more critical. The identification of natural fractures from those induced fracture by production-related activities becomes a major obstacle in fractured core investigations. Taking the case study of core fracture of Yanchang Formation in the Ordos Basin, this paper provides a comprehensive review of the physical characteristics of natural and induced fracture. The paper focuses on analysisthe morphology, evolution of natural fracture, growth modes of induced fracture, and introduces terminology used to classify fracture and surface structures formed by foreign scholars. The fracture surface structure is the key to trace the dynamics of propagation of a mode I fracture(or joint)from inception to final arrest. It is useful in fractured core analysis as well as outcrop investigations.