单参数抛物线准则和霍克布朗准则在井壁稳定分析中的应用研究

发布时间：2018-01-09 11:09

本文关键词：单参数抛物线准则和霍克布朗准则在井壁稳定分析中的应用研究　出处：《西南石油大学》2017年硕士论文　论文类型：学位论文

【摘要】：应用最广的井壁稳定分析强度理论是Mohr-Coulomb强度准则,但线性的强度准则难以准确描述围压条件下的岩石强度特性,尤其是深部地层岩体,因此,选取更优的强度准则将有利于提高井壁稳定预测精度。通过本文的研究取得了以下的成果和认识:(1)推导了两个抛物线型强度准则。在抛物线Mohr强度准则(Fairhurst准则)的基础上,结合大量文献资料中所呈现的岩石强度数据特征,推导了单参数抛物线强度准则和Hoek-Brown强度准则,并分析两者在主应力空间的几何形态特征。(2)分析了两个抛物线强度准则的拟合精度和应用优势。通过选用合适的拟合指标,采用数理统计及数值拟合的方法,着重分析了 Mohr-Coulomb准则、Hoek-Brown准则和单参数抛物线准则的拟合精度,凸显出抛物线型强度准则在描述围压条件下的岩石强度非线性破坏特征所呈现出的优势。利用两个现场算例进行了井眼轨迹和钻井液密度配置的优化分析,通过实例应用验证了抛物线型强度准则较Mohr-Coulomb准则的优越性。(3)确定了两个抛物线型强度准则的准则参数并分析两者的应用条件。对单参数抛物线准则进行了围压大于15MPa条件下的岩石强度拟合特性分析,得出了该强度准则在高围压条件下的高精度预测优势和准则参数获取方法;利用等效Hoek-Brown和Mohr-Coulomb法确定了 Hoek-Brown准则中的岩体参数m、s,建立起岩石强度参数(内聚力和内摩擦角)和准则参数m和s的对应转化关系。(4)建立了考虑孔隙度和含水率的岩石单轴抗压强度预测模型。单轴抗压强度是岩石最重要的力学和强度性质之一,同时也是单参数抛物线准则的准则参数;采用二元分析方法,建立了考虑孔隙度和含水率的岩石单轴抗压强度预测模型,并给出了模型参数的确定方法和明确的物理意义,为实验室结果外推于工程实际提供了参考方法。(5)分别建立了基于两个强度准则的井壁坍塌模型。采用Bradley厚壁圆筒井周应力分布弹性解,分别建立了基于Hoek-Brown准则和单参数抛物线准则的井壁稳定分析模型,给出了考虑渗流和不考虑渗流工况条件下的井壁坍塌压力计算式。
[Abstract]:Borehole stability is the most widely used analysis of strength theory Mohr-Coulomb strength criterion, but the linear strength criterion is difficult to accurately describe the surrounding rock strength characteristics under pressure, especially in deep strata, therefore, select the strength criterion better will help improve the wellbore stability prediction precision. The following results and understanding are obtained through the research in this paper: (1) derived two parabolic parabolic Mohr strength criterion. The strength criterion (Fairhurst criterion) on the basis of the combination of rock strength data characterized by a large number of documents in the derivation of a single parameter parabolic strength criterion and Hoek-Brown strength criterion, and the analysis of both geometric morphological characteristics of space force in the main. (2) analyzed two parabolic strength criterion fitting precision and application advantages. By selecting the appropriate fitting index, using mathematical statistics and numerical fitting method, a Analysis of Mohr-Coulomb criterion, Hoek-Brown criterion and the fitting precision of single parameter parabolic criterion, highlighting the strength of the Rock Nonlinear Parabolic strength criterion in the description of the confining pressure under the condition of failure characteristics by showing the advantage. By two field examples of the well trajectory and drilling fluid density optimization analysis, application examples to verify the superiority of the parabolic strength criterion than the Mohr-Coulomb standard. (3) the application conditions of two parabolic failure criterion and the analysis of both parameters determined. For single parameter parabolic rule of confining pressure is more than fitting characteristics of rock strength under the condition of 15MPa analysis, it was concluded that the strength criterion of acquisition method in high precision the predictive advantage and criterion parameters under high confining pressure; using the equivalent Hoek-Brown and Mohr-Coulomb method to determine the parameters of rock mass m, Hoek-Brown standards in s construction Set up the rock strength parameters (cohesion and internal friction angle) transformation and corresponding criterion parameters m and S. (4) considering the uniaxial compressive strength of the rock porosity and water content prediction model. The uniaxial compressive strength of rock is one of the most important properties and mechanical strength, and is also a single parameter criterion parabolic criterion; using two element analysis method, prediction model is established considering the uniaxial compressive strength of rock porosity and water content, and gives the method to determine the model parameters and clear physical meaning, the reference method for laboratory results in practical engineering. (5) were established two borehole collapse model based on the strength criterion. Using Bradley thick wall cylinder well circumferential stress distribution of elastic solution, respectively establish the analysis model of wellbore stability criterion and single parameter parabolic Hoek-Brown based criteria are given considering the seepage and The calculation formula of borehole wall collapse pressure is not considered under the condition of percolation.

【学位授予单位】：西南石油大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TE21

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