丁山￣东溪地区页岩裂缝发育特征及主控因素

Development characteristics of shale fracture and main controlling factors  in Dingshan-Dongxi area

谢佳彤

中国石化勘探分公司，四川 成都 610041 西南石油大学地球科学与技术学院，四川 成都 610500

SINOPEC Exploration Company, Chengdu 610041, China School of Geoscience and Technology, Southwest Petroleum University, Chengdu 610500, China

基于对川东南丁山￣东溪地区龙马溪组页岩地表露头及岩心的裂缝特征的观察与统计，同时参考各样品实验测试数据，对裂缝发育特征与主控因素进行了研究与分析，并探讨了裂缝对含气性的影响。结果表明：研究区龙马溪组页岩裂缝以高角度裂缝为主，主要为剪切缝，为3期形成，第1期裂缝受到SE向的应力作用形成NE向的断裂，第2期及第3期受到NE向的应力作用形成NW向的裂缝。裂缝发育受构造作用、岩层厚度、矿物组分以及有机碳质量分数等多种因素影响，其中构造作用主要受到褶皱和断层位置的影响，在非构造因素中，矿物组分中脆性矿物含量越高，岩层越容易发生破碎，裂缝越发育，同时，有机碳质量分数高也对裂缝发育起着促进作用。研究区龙马溪组裂缝的发育对页岩气的储存以及运移都有着不可忽视的重要作用，对提高页岩气产量及含气性有着至关重要的作用。

Based on the observation and statistics of the fracture characteristics of the surface outcrops and cores of Longmaxi Formation shale in Dingshan-Dongxi area, southeast Sichuan, and referring to the experimental test data of various samples, the fractures development characteristics and main controlling factors are studied and analyzed, and the impact of fractures on gas bearing property is discussed. The results show that the shale fractures of Longmaxi Formation in the study area are mainly high angle fractures, mainly shear fractures and formed in three stages. Fractures of the first stage are affected by the SE direction stress, forming the NE direction fractures. The second and third stages of the fractures are affected by the NE direction stress, forming the NW direction fractures. Fracture development is affected by many factors such as tectonism, rock thickness, mineral composition and organic carbon content, among which tectonism is mainly affected by folds and fault locations. Among non structural factors, the higher the content of brittle minerals in mineral components, the easier the rock formation is broken, and the more developed the fractures are. At the same time, the high content of organic carbon also promotes the development of fractures. The development of fractures in Longmaxi Formation in study area plays an important role in shale gas storage and migration, and plays a crucial role in improving shale gas production and gas bearing capacity.

10.6056/dkyqt202303005