低—非孔隙岩石中走滑断裂带内部结构的形成演化

Formation and evolution of internal structure of strike-slip fault zones in low-non porosity rocks

王孝彦 2 高强³ 孟令东¹ 王海学¹ 魏志鹏⁴

东北石油大学CNPC断裂控藏研究室，黑龙江 大庆 163318 中国石油塔里木油田分公司勘探开发研究院，新疆 库尔勒 841000 中国石油大庆油田有限责任公司第八采油厂，黑龙江 大庆 163000 中海油田服务股份有限公司，天津 300450

Laboratory of CNPC Fault Controlling Reservoir, Northeast Petroleum University, Daqing 163318, China Research Institute of Exploration and Development, Tarim Oilfield Company, PetroChina, Korla 841000, China No.8 Oil Production Plant, Daqing Oilfield Co. Ltd., PetroChina, Daqing 163000, China Oilfiled Services Limited, CNOOC Ltd., Tianjin 300450, China

文中描述了低—非孔隙岩石中走滑断裂带特征，分析了断裂带内部结构的物性特征，研究了走滑断裂带的形成过程。研究表明，低—非孔隙岩石中走滑断裂带具有典型的“二元结构”，即断层核和破碎带。当围压和有效压力上升时，断层核和破碎带的孔渗性均降低，但破碎带的物性要好于断层核。另外，低—非孔隙岩石中走滑断层成核作用，具有破碎带成核、压溶缝成核和先存节理成核3种形式。早期碳酸盐岩中普遍存在破碎带，并且在应力集中处破碎程度严重，随着断层逐渐演化形成断层核；早期低孔隙灰岩中会形成开启型雁列岩脉，在雁列脉间的压性岩桥内形成第1期压溶缝，其持续开启时，沿岩脉形成的剪切作用使岩块滑动，导致压溶缝受到剪切，形成第2期压溶缝，最终形成断裂带；低孔砂岩、花岗岩及变质岩中存在早期形成的节理，在剪切作用下，形成次级裂缝，次级裂缝与小型断层逐渐连接起来，形成了走滑断裂带。

In this paper, we described the internal structure of strike-slip fault zones in low￣non porosity rocks and studied the physical property and formation process of the strike-slip fault zones. The research shows that the internal structure has a typical     "two-component" structure: fault core and damage  zone. With the rising of the confining pressure and effective pressure, both the porosity and the permeability of the fault core and damage zone decrease, but the physical property of the damage zone is better than that of the fault core. There are three ways of nucleation of the strike-slip fault zones: nucleation in the damage zone, nucleation in the pressure-solution seams and nucleation in the pre-existing joints. The damage zones formed in the early days are common in the carbonate rocks and were broken seriously in stress concentration, they turned into fault core gradually with the evolution of fault; the opening-mode echelon veins formed early in the low porosity limestone, the first generation pressure-solution seams formed between the bending of the intact rock, when the echelon veins are open, the slip along the echelon veins will cause shear along the pressure-solution seams, which forms the second pressure-solution seams and develops into fault zones finally; the pre-existing joints exist in the low porosity sandstone, granite and metamorphic rocks, and the shear along the mineral-filled joints causes the secondary fracture separation, With the shear action, small faults will gradually connect each other and form a strike-slip fault zone.

10.6056/dkyqt201506001