不同边界条件断层端部应力集中效应及对裂缝发育的启示

The stress concentration effect at fault end under various boundary conditions and its implications for fracture development

邱登峰 云金表 刘全有 周雁 宁飞 宋海明

Qiu Dengfeng Yun Jinbiao Liu Quanyou Zhou Yan Ning Fei Song Haiming

与断层应力集中相关的裂缝发育区是致密油气和页岩油气聚集的有利区。以光弹性物理模拟和有限元数值模拟为技术手段，探讨断层端部应力场的平面展布规律，并结合弹性力学理论分析，解析断层端部应力场的分布机理。结果表明，挤压背景下断层端部的压应力集中区以断层端部圆弧最凸出端点为中心以双曲线形式向外呈“8”字形展开状延伸，其控制范围随边界应力强度增加而增大；在0°~90°范围内随断层走向与边界应力方位夹角增大呈整体增强的趋势，在75°时最大，断层形态及模拟时的建模方式对断层端部应力场有重要影响。断层端部的应力集中区是裂缝储层油气勘探开发的高潜力区。

A fracture development play related to stress concentration of fault zone has high potentials for tight reservoirs and shale oil and gas.This study combined the methods of photo elastic physical modeling and finite element simulation to discuss the planar distribution patterns of stress field at fault's end,and took advantage of the elasticity mechanical theory to analyze the mechanism of stress field distribution.The results indicate that the fault's end displays the concentration of compression stress under the compression background.The stress concentration district extends outward in the shape of numeral "8" following a hyperbolic path centered on the most salient point of the fault's arc end,and its influence range increases with the growth of boundary stress intensity.The stress concentration degree tends to get stronger with the angle between boundary stress direction and fault strike increasing when the angle in the range of 0° to 90°,and reaches its summit at 75°.Besides,both the shape and the modeling method of fault have a significant impact on fault's end stress field.All in all,the stress concentration district at the fault's end has great potentials for the exploration and development of fracture reservoirs.

10.11743/ogg20190121