利用分形方法研究裂缝面形貌特征

发布时间：2018-05-29 02:04

本文选题：压裂 + 裂缝壁面　；参考：《成都理工大学》2015年硕士论文

【摘要】：在当今的国内各种油气藏的开发过程中,许多低渗透储层油气井在完井过后一般无天然产能,所以必须经过水力压裂形成足够长的人工裂缝,或是沟通天然裂缝才能够实现商业开发。裂缝的存在大大改善储层的渗透能力,所以对裂缝的研究手段也愈发多种多样。但由于裂缝的分布复杂、规律性差,又受到观测、探测手段以及研究方法的限制,对裂缝的精细描述和预测,仍是一个尚未完全解决的难题。以往对裂缝性储集层的应力敏感性研究多从探讨裂缝导流能力随应力的变化规律着手,但裂缝闭合与其表面的微观形态也有着十分密切的关系。分析裂缝的微观形态及其在各种应力下的变化规律有利于预测地层条件下的裂缝宽度和导流能力,从而为裂缝性油气藏保护提供帮助。人工裂缝宽度的闭合量与裂缝表面的微观形态有着十分密切的关系。本文通过分析研究前人对裂缝微观形态数字化的方法,利用分形几何学的方法结合传统的数字化的裂缝研究手段,研究岩石裂缝面的接触关系。首先,通过8组岩石在10MPa、20MPa、30MPa、40MPa四个不同闭合压力条件下测试导流能力,并做出32幅岩石裂缝壁面间距图;其次,是利用分形几何学的基本特征推导出基本的数学模型,使用Matlab软件编程求取分形维数,利用分形维数对裂缝间距图进行表征,分析分形维数与裂缝壁面的接触关系;再次,是研究前人岩石裂缝在不同闭合压力下的闭合规律以及岩石裂缝在不同闭合压力条件下的导流能力预测模型,将分形几何学方法融入到岩石裂缝在不同闭合压力条件下的规律中去,推导出分形维数与吻合度的关系式和分形维数与裂缝开度的关系式,并利用这个关系式推导出不同闭合压力条件下的导流能力预测模型。最后,总结分析导流能力实验结果,对比模型计算的预测值和实验得到的实测值,分析了误差产生的原因。本文取得的主要研究认识与成果有:(1)分析总结前人数字化研究岩石裂缝壁面形态的常规手段的研究进展,结合分形几何学手段,提出利用数字化方法求取分形维数来表征裂缝壁面的接触关系,研究裂缝壁面接触关系与导流能力的研究思路;(2)分析总结研究岩石裂缝形态方法的优缺点以及分析研究常用的四种求取分形维数的模型公式,提出未来研究裂缝形态的发展趋势;(3)引入最新型的三维形貌扫描仪获得高精度的岩石裂缝壁面间距图,使用Matlab程序编程获得数字图像计盒维数计算程序,求取分形维数。(4)利用分形维数的特点推导出岩石裂缝接触部分面积与分形维数的关系表达式。利用分形维数表征岩石裂缝壁面间距图,阐述分形维数与裂缝壁面接触支撑部分的分布关系。(5)通过吻合度的概念和求取方法,推导出分形维数与导流能力的关系表达式和裂缝开度与分形维数的表达关系式。(6)根据前人的研究成果改进后建立新的关于分形维数的岩石裂缝闭合模型。(7)结合裂缝开度与分形维数的表达关系式与狭义立方定律,求解计算不同分形维数条件下的导流能力预测模型。本文宗旨在于通过分析裂缝的微观形态及其在各种应力下分形维数的变化规律,有利于预测地层应力条件下的裂缝开度及其导流能力、裂缝相互支撑关系。引入分形几何学的方法完善不同闭合压力下导流能力模型,希望通过加入新的数学方法,能够更加有效的研究岩石裂缝间距分布对导流能力的影响,丰富了压裂工艺行业的基础理论研究的手段方法。同时,这方面的分析也实用于对裂缝性油气层的开采,做出更符合实际生产的动态预测,从而为裂缝性油气藏的开发、管理提供有益的帮助。
[Abstract]:In the development of all kinds of oil and gas reservoirs in China today, many low permeability reservoirs have no natural productivity after completion, so they must be fractured by hydraulic fracturing to form long enough artificial cracks, or communicate natural cracks to achieve commercial development. There are also a variety of research methods. However, due to the complex distribution of the cracks, poor regularity, observation, detection and research methods, the fine description and prediction of cracks are still a difficult problem to be solved. In the past, the stress sensitivity study of fractured reservoir is mostly from the study of fracture conductivity with stress. The fracture closure is closely related to the microscopic morphology of the surface. The analysis of the microscopic morphology of the crack and its variation under various stresses is beneficial to the prediction of the crack width and the diversion ability under the formation conditions, thus providing help for the protection of fractured oil and gas reservoirs. It is closely related to the microscopic morphology of the crack surface. Through the analysis and study of the methods of digitizing the microscopic morphology of the fracture, this paper studies the contact relation of the rock fracture surface by means of fractal geometry and the traditional digital crack research means. First, 8 groups of rocks are in 10MPa, 20MPa, 30MPa, and 40MPa. Under the same closed pressure condition, we test the diversion capacity and make 32 wall spacing maps of rock cracks. Secondly, the basic mathematical models are derived from the basic features of fractal geometry. The fractal dimension is obtained by Matlab software programming, and fractal dimension is used to characterize the crack spacing map, and the contact relation between the fractal dimension and the crack wall is analyzed. Thirdly, it is to study the closed law of the rock cracks under the different closed pressure and the prediction model of the conductivity of the rock cracks under the different closed pressure conditions, and integrate the fractal geometry method into the law of the rock cracks under the different closed pressure conditions, and deduce the relation and fractal of the fractal dimension and the coincidence degree. The relationship between the dimension of the fractal dimension and the opening degree of the crack is used, and the prediction model of the diversion capacity under different closed pressure conditions is derived by this formula. Finally, the results of the conductivity experiment are summarized and analyzed. The causes of the error are analyzed by comparing the predicted values of the model and the measured values obtained by the experiment. The main research knowledge and results obtained in this paper are obtained. There are: (1) analysis and summary of previous research progress on the conventional means of digital research on the morphology of rock fissure wall, and combining fractal geometry to obtain fractal dimension to characterize the contact relationship of fracture wall, study the contact relationship and flow ability of fracture wall, and (2) analyze and study rock cracks. The advantages and disadvantages of the morphological method and the analysis and study of the four commonly used model formulas for obtaining fractal dimension, put forward the development trend of the future research on the fracture morphology. (3) introducing the latest three-dimensional topography scanner to obtain the high precision wall space map of the rock cracks, and using Matlab program programming to obtain the calculation program of the digital image box counting dimension. Fractal dimension. (4) using the characteristics of fractal dimension, the relation expression of the contact part area and fractal dimension of rock cracks is derived. The fractal dimension is used to characterize the wall space of the rock cracks, and the distribution relation between the fractal dimension and the contact support part of the fracture wall is expounded. (5) the fractal dimension is deduced through the concept and method of the anastomosis degree. Expression of relation expression with diversion capacity and expression of fracture opening and fractal dimension. (6) a new rock fracture closure model on fractal dimension is established on the basis of previous research results. (7) combining the expression of crack opening and fractal dimension and the narrow sense formula, solving the calculation of different fractal dimension conditions The aim of this paper is to analyze the microscopic morphology of the cracks and the variation of fractal dimensions under various stresses. It is beneficial to predict the opening degree and the conductivity of the cracks under the stress conditions and the mutual support relationship of the cracks. The fractal geometry method is introduced to improve the flow conductivity model under different closed pressure. It is hoped that by adding new mathematical methods, it can be more effective in studying the influence of the distribution of rock crack spacing to the diversion capacity, and enriches the method and method of the basic theory research in the fracturing technology industry. At the same time, the analysis of this aspect is also useful for the exploitation of fractured reservoir and makes the dynamic prediction more consistent with the actual production. The development and management of fractured reservoirs provide useful help.
【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TE357.1

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