黔北地区构造特征与下寒武统页岩气储层裂缝研究

裂缝发育程度是页岩气储层的主控因素之一,而裂缝的形成与构造特征密切相关。在对黔北地区构造特征分析的基础上,对该区下寒武统牛蹄塘组黑色页岩地层的裂缝特征及分布进行了研究。认为黔北地区褶皱、断裂发育复杂,褶皱整体以隔槽式为主,断裂是在多个走向断裂体系相互切割、联合下形成的,各断裂体系的主形成期具有差异性;构造裂缝是下寒武统黑色页岩层段的主要裂缝类型,而且以水平缝与低角度缝所占比例大。裂缝发育区的分布主要受到断裂带的控制,其中以北东向和北北东向断裂体系的控制作用最为显著,裂缝发育区多位于断裂带的末端、拐点处、不同走向断裂带相交处和相同走向的断层夹持带等应力集中部位。其次,在背斜的高陡部位,也有利于裂缝的形成。

Structural Features in Northern Guizhou Area and Reservoir Fracture of Lower Cambrian Shale Gas

Fracture development is one of controlling factors for shale gas reservoir,while there is close correlation between fracture and structural characteristics.Based on structural characteristics in the northern Guizhou area,we discuss the fracture features and distribution of lower Cambrian black shale.In the northern Guizhou area,the folds are mainly trough-like,and the faults are formed under cut and joint of fault system in different directions.The main times of fault system with different trending direction are different.Structural fractures are the main fracture types of the black shale and the horizontal fractures and low-angle fractures are dominant.The fracture-developed area is controlled by faults,especially NE-and NNE-striking faults.The fracture-developed areas are mainly lactated in end of the faults,inflection point,junction of different strike faults,and place between faults with similar striking orientation.Meanwhile,the steep part of anticline is also profitable to the fracture formation.