微观条件下储层天然裂缝闭合特征研究

Study on the Closure Law of Natural Fractures in Reservoir under Micro Conditions

当前针对储层天然裂缝闭合的研究仍旧局限于在建立模型的基础上探讨模拟有效应力对裂缝闭合的影响,几乎没有涉及到微观条件对裂缝闭合的影响。为此,对单条天然裂缝在储层中的应力状态进行分析,在B&S粗糙表面复合模型的基础上,依据赫兹弹性理论,从微观角度建立裂缝表面微凸体的力学模型,将单条裂缝的闭合问题转化为微凸体压缩的问题,根据微凸体的各类特性对天然裂缝的闭合进行探究。从裂缝岩石性质和微凸体分布特点出发,利用计算机模拟分析不同的泊松比、微凸体高度均方差、微凸体高度期望值对裂缝闭合过程的影响。通过不同情况下的模拟和分析,得出三种情况下的储层天然裂缝闭合量的变化规律。对于裂缝发育较强的油气藏开发具有一定的指导意义。

At present,the research on the natural fracture closure of reservoir is still confined to the influence of the simulation effective stress on the crack closure,which is based on the establishment of the model. Therefore,the single natural fractures in reservoirs should stress analysis,in the B S rough surface composite model based,based on Hertz theory of elasticity,fracture surface micro convex body mechanical model was established from the microscopic point of view,a single crack closure is transformed to micro convex body compression problems,according to the micro convex body with all kinds of characteristics of natural fracture closed to explore. The influence of different Poisson＇s ratio,height mean square deviation and high expectation value on the fracture closure process is analyzed by computer simulation. Through the simulation and analysis under different conditions,the change law of natural fracture closure in three cases is obtained. Certain directive significance was presented to the development of oil and gas reservoirs with strong crack growth.