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“层内爆炸”数值模拟研究

Numerical Simulation of In-Fracture Explosion

【作者】 王胡振

【导师】 刘振宇;

【作者基本信息】 大庆石油学院 , 油气田开发工程, 2009, 硕士

【摘要】 “层内爆炸”作为一项低渗透油田开发新技术,在爆炸过程中受多种因素影响产生的裂缝的长度和角度都具有任意性,大大增加了对“层内爆炸”后形成的复杂裂缝进行模拟研究的难度。本文应用有限元法能够比较精确地模拟复杂边界,网格的划分比较灵活的特点,成功实现了对“层内爆炸”后形成的复杂裂缝的合理描述和数值模拟计算。在有限元法基本原理基础上,将基质和裂缝看作一个渗流系统建立了统一的两相渗流问题的有限元模型。模型中将裂缝处理为直线,并且假设裂缝与基质接触处的压力是连续的。基质的网格剖分采用任意形状的四边形单元,采用等参元对渗流方程在空间上离散,采用向后差分在时间上离散。在此基础上采用元件化的程序设计思想利用Fortran语言编制了有限元法的数值模拟器,得到了稳定的计算结果,解决了利用有限元法求解两相复杂渗流问题稳定性差的难题。通过与ECLIPSE软件进行算例对比,验证了本文有限元数学模型的准确性和正确性。在此基础上,使用数值模拟器针对“层内爆炸”后形成的复杂裂缝,对裂缝数量、裂缝长度、网缝、任意缝进行了模拟研究,得到了不同裂缝参数下压力分布图及饱和度分布图,研究了不同裂缝参数对油井的动态曲线的影响规律并进行了深入的对比分析,对“层内爆炸”后储层的复杂渗流机理有了深入的认识,为“层内爆炸”技术的现场应用提供了理论指导。

【Abstract】 "In-fracture explosion" is a new technology in low-permeability field development. While the process of explosion,the length and angle of fracture are random by the affection of many factor,this increase the difficulty to simulate complex fractures after "In-fracture explosion".Finite Element Method can precise simulate complex boundary and Grid are divided into arbitrary.Reasonable description and simulate to complex fractures after "In-fracture explosion" are successful.Starting form basic differential equation finite element model of two-phase flow is established based on Finite Element Method theory. In this model, fractures are idealized as lines in two-dimensional. With the assumption of continuity of pressures across the fracture-matrix boundary.The meshes of matrix use the arbitrary shape quadrilateral element. Those equations are dispersed in space by isoparametric element method and in time by using backward difference. A numerical simulator is established by FORTRAN and get steady results.The low steady of simulate two-phase complex problem by Finite Element Method is resolved.By comparing to example of ECLIPSE software the accuracy and correctness of the finite element mathematical model is verified. On this basic,The influence of four variants to the production performance of fractured well, such as fracture number, fracture length and complicated fracture are simulate by the use of numerical simulator. The pressure field and saturation field are given. The influence of different fracture parameters to production performance curves is deeply analyzed.The complex percolation mechanism after "In-fracture explosion" is deeply understood and can supply theoretical guidance to the pplication in field.

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