渗流作用下泥页岩井壁损伤失稳研究

发布时间：2018-06-10 07:50

本文选题：渗流 + 流固耦合　；参考：《西安石油大学》2017年硕士论文

【摘要】：避免井壁失稳所造成的工程事故是油气田工业生产中的一个严峻挑战,而泥页岩井壁又常常是事故多发的一个井位段,所以掌握和了解其失稳机理要素才能够有目的、有针对性的进行预防和补救。本文在泥页岩流固耦合、力化耦合等方面的研究基础上着重考虑了流体作用于泥页岩井壁后对围岩体造成的损伤破坏,并通过等效应力原理在泥页岩井壁流固耦合模型中引入化学场因素,凭借岩石物性状态方程、流体质量方程及动量与能量方程建立了泥页岩井壁流固化耦合模型。分析与研究得出:(1)在受近井壁地应力的分布影响下泥页岩围岩初始缺陷会受到流体入侵造成微缺陷的损伤,通过应力应变的本构关系给出泥岩围岩在弹塑性区的损伤状态方程。(2)采用数值模拟求解模型方程,利用有限元ANSYS软件仿真钻开泥岩地层时地层随地应力的分布影响,结果表明地层钻开的瞬间,受最大最小地应力的影响井壁围岩体发生变形位移,其变形位移大小与方向受地应力分布的影响。(3)考虑流体作用于泥页岩围岩所带来的损伤时,本文依据FLUENT软件进行流体入侵泥岩围岩的仿真模拟,结果表明流体在井壁附近地层应力较小处对泥岩的损伤破坏较为严重,其严重程度受流体压力和地应力分布的影响。(4)表征流体特性对泥岩的损伤破坏情况,分别用不同流体饱和过后的泥岩试件作力学实验分析,实验结果得出泥岩的抗拉抗压强度特性发生变小变弱现象,其弹性模量、内摩擦角、粘聚力等力学参数值也出现不同程度的降低。就本实验而言,钻井液作用后泥岩试件的强度特性变化较为明显。
[Abstract]:To avoid engineering accidents caused by wellbore instability is a severe challenge in oil and gas field industrial production, and mud shale wellbore is often a section where accidents occur frequently. Therefore, it is only by mastering and understanding the elements of its instability mechanism that it can have a purpose. Prevention and remedy are carried out in a targeted manner. In this paper, based on the study of fluid-solid coupling and mechanical coupling of shale, the damage and failure of surrounding rock caused by fluid acting on shale shaft lining are considered emphatically. The chemical field factor is introduced into the fluid-solid coupling model of shale wellbore by the principle of equivalent stress. Based on the equation of state of rock physical property, fluid mass equation and momentum and energy equation, the coupling model of shale shaft wall flow solidification is established. The analysis and study show that the initial defects of shale surrounding rock will be damaged by fluid intrusion under the influence of near wellbore stress distribution. Through the constitutive relation of stress and strain, the damage state equation of mudstone surrounding rock in elastic-plastic zone is given. The model equation is solved by numerical simulation, and the distribution of stratum with ground stress is simulated by finite element ANSYS software. The results show that the deformation and displacement of wall rock mass is affected by the maximum and minimum in-situ stress, and the deformation displacement is affected by the distribution of in-situ stress at the moment of drilling, and the damage caused by fluid acting on the surrounding rock of shale is considered. Based on fluent software, the simulation of fluid intrusion into mudstone surrounding rock is carried out. The results show that the fluid damage to mudstone is more serious when the formation stress is small near the shaft wall. Its severity is affected by the distribution of fluid pressure and in-situ stress. The damage and failure of mudstone caused by fluid characteristics are characterized. The mechanical experiments of mudstone specimens after different fluid saturation are carried out. The experimental results show that the tensile and compressive strength of mudstone becomes smaller and weaker, and the mechanical parameters such as modulus of elasticity, angle of internal friction and cohesion also decrease to some extent. As far as this experiment is concerned, the strength characteristic of mudstone specimen changes obviously after drilling fluid action.
【学位授予单位】：西安石油大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TE21

【相似文献】