【作者】 李田军；

【导师】 鄢泰宁；

【作者基本信息】 中国地质大学 ， 地质工程， 2012， 博士

【摘要】 随着对地下矿产资源的需求和消耗的急剧增加,资源紧缺和矿产资源的供给与保障问题已经成为制约国民经济发展的“瓶颈”。钻探是深部地质找矿工作中不可替代的技术手段,而钻探工作中消耗在岩石破碎方面的资金和材料是一个非常巨大的数字。孔底岩石破碎机理研究是钻探(钻井)专业重要的基础理论研究方向之一,是设计高效、长寿命岩石破碎工具及制定合理钻进规程的理论基础。虽然国内外对金刚石钻头在孔底岩石破碎机理研究已做过大量的工作,但有关金刚石的碎岩机理及破碎过程至今尚未被彻底掌握,仍然没有一个较好的物理模型。前人在岩石破碎机理研究时,大都是以球形、圆锥形或圆柱平底压模压入弹性半空间体时的应力和变形结论为基础,考虑岩石在切削具静力作用下的应力分布等,以此来研究岩石的破碎问题。这对表镶或孕镶金刚石钻头钻进岩石破碎机理研究,是比较合适的。随着PDC生产技术的提高和PDC钻头设计制造技术的进步,国内外已经在油井钻探、煤田钻探和部分岩心钻探中大量使用PDC钻头,PDC钻头适应的地层也越来越广泛,但是理论研究尚远落后于工程实践。为了进一步扩大PDC钻头的应用范围,为实现PDC钻头的科学设计与应用,必需清楚了解PDC钻进岩石破碎的影响因素和规律,以便有效地利用和掌握它们。这就是本论文研究的目的。本论文在前人研究岩石破碎机理的基础上,采用理论分析与建模、实验研究和仿真分析相结合的方法进行研究。由于PDC斜镶入在钻头胎体或刚体上,因此PDC总是以斜向压入切削方式破碎岩石,其压头形状既不同于球形或圆锥形压头压入,又不同于圆柱平底压头压入。因此,PDC钻进岩石破碎机理的研究,不能单纯再以球形、圆锥形或圆柱平底压模压入的结论来分析,需要针对具体的斜镶PDC形状,结合具体的岩石破碎方式来进行分析。通过PDC压入切削岩石时的受力分析,运用接触力学理论,详细推导了单个PDC片与岩石之间的接触压力,建立作用荷载和压入岩石深度的关系模型；结合不同尺寸、形状PDC片和不同几何结构的PDC钻头与岩石之间的接触作用分析,建立相关的物理模型,分析了对接触压力的影响因素及其规律。在此基础上,基于相关岩石强度准则,研究了PDC在双向荷载作用下钻进岩石时,岩石破碎前的裂纹萌生与破裂面位置,建立PDC钻进岩石破碎条件的理论模型。以测定试验岩石和PDC的力学性能为数据基础,采用不同尺寸和数量PDC进行压入切削岩石的室内试验,并设计一款钻头进行台架试验和实钻试验。根据试验数据分析各项参数之间的相关性和规律,并与理论研究的结果进行对比。运用ANSYS Workbench中的Design Modeler模块建立各种不同形状尺寸PDC和不同结构PDC钻头压入切削岩石的几何模型,再由Static Structural及Transient Structural模块进行有限元分析,并对分析结果进行后处理。最后结合Design Explorer模块对各项参数进行相关性和优化设计分析。具体章节内容如下：第一章是概述性章节,主要介绍了本论文的研究意义和目的,综述了国内外对岩石破碎和PDC受力的理论研究现状及趋势,并阐述了论文的研究内容和方法。第二章是关于PDC受力分析的研究,目的是从理论角度搞清楚接触压力的影响因素,及接触压力与PDC作用力之间的关系。当整形PDC压入切削岩石时,PDC与岩石之间主要有两个接触面。从接触力学理论角度,对PDC与岩石之间各接触面的接触压力进行了详细地推导。再根据PDC受力分析,由极限平衡条件,得到作用于PDC的轴向力和切向力与PDC压入岩石深度的关系,表明接触压力与压入岩石深度是成非线性比例关系。通过对PDC钻头的受力分析,得出钻头轴压力和扭转力矩与单个PDC受力、钻进机械速度等的关系。第三章是关于PDC压入切削岩石破碎的条件分析。根据接触压力的理论计算公式,由岩石抗压的力学性能,分析PDC压入岩石的破碎条件。结合相关岩石强度理论,分析PDC切削岩石时,岩石初始裂纹的萌生、发展条件和宏观破碎的开裂面,得出PDC钻进岩石破碎的条件模型,并对PDC钻进岩石的破碎过程进行了定性分析。当非整形PDC压入岩石时,由于PDC与岩石之间接触面的形状和尺寸变化,必然影响其接触压力。仍然运用相关接触力学理论,对一种被切割小部分的非整形PDC与岩石之间各接触面的接触压力进行分析,并将分析结果与整形PDC的接触压力计算公式进行对比。结果表明,由于PDC压入切削岩石破碎的形式不变,PDC与岩石之间的接触压力计算形式不变,但相关系数与PDC的几何特性有关,并对影响接触压力的PDC几何参数因素进行了分析。第四章是关于试验研究和结果分析,目的是验证理论研究的结论。首先采用相关试验设备测试试验岩石和PDC的力学性能,将试验数据作为试验研究和数值分析的数据基础。设计了几种整形和非整形PDC压入切削岩石的物理模型,并进行微钻试验。根据各种试验结果,分析影响PDC钻进岩石破碎效果的各项因素。根据前期研究结论,设计、制造一款PDC钻头,并进行台架试验和生产试验,对试验参数和效果进行了分析。第五章是在理论和试验研究的基础上,进行PDC压入切削岩石的数值分析。设计了几种仿真几何模型：一是单个整形PDC压入切削岩石模型；二是单个非整形PDC压入切削岩石模型；三是分别由两个和六个PDC组成的组合PDC压入切削岩石模型。在仿真分析过程中,都考虑了切入角和扭转角等几何因素的影响。通过ANSYS分析结果,采用Design Explorer进行了各参数之间的相关性和优化分析。应力、变形云图和相关性曲线表明,PDC的尺寸和形状对岩石接触压力和变形都有较大影响,而且理论曲线与数值分析曲线比较符合,这也说明理论分析的正确性。第六章是结论性章节,对全文的相关结论进行总结,并分析和展望了今后继续本课题研究需要深入的问题。总之,本文通过理论推导建模,试验分析及ANSYS数值分析,围绕PDC压入切削岩石破碎的机理研究取得了一定的成果。更多还原

【Abstract】 With the dramatic increase in the demand and consumption of underground mineral resources, the scarcity of resources and the supply of mineral resources and protection has become a "bottleneck" restricting the development of the national economy. Drilling is irreplaceable technical means in deep geological prospecting work, while drilling funds and materials consumed in the rock crushing is a very huge number.The crushing mechanism of hole bottom rock is one of important drilling professional basic theoretical research direction, and is the theoretical basis of design efficient, long-life rock crushing tools and develop reasonable Drill in. The study in domestic and international of rock crushing mechanism while the diamond drill drilling in hole bottom has done a lot of work, but about diamond rock fragmentation mechanism and crushing process has not yet been thoroughly mastered, still do not have a good physical model.Previous rock crushing mechanism studies, mostly based on spherical, conical or cylindrical flat bottom pressure molded into the conclusions of the stresses and deformations in the elastic half-space basis, considering the rock under the action of cutting static stress distribution, so to study the rock crushing problems. This is more appropriate for the study of rock fragmentation mechanism while table inlaid or impregnated diamond bit drilling.As the improvement of production technology of PDC and the advances of design and manufacturing technology of PDC bit, at home and abroad PDC bit has been a lot of use in oil well drilling, coal field drilling and core drilling, and PDC drill bit to adapt to the strata are more and more widely, but the theoretical research is still far behind in engineering practice. For further expand the range of applications of the PDC bits, and for the realization of the scientific design and application of PDC bits, it is necessary to clearly understand the PDC drilling rock crushing impact factors and laws, in order to effectively utilize and master them. This is the purpose of this thesis.The subject study is using a combination of the theoretical analysis and modeling, experimental research and simulation analysis, on the basis of the theoretical analysis and modeling of the rock fragmentation mechanism in previous research. Because the PDC of the PDC bit is in oblique cutting way to pressed into broken rock, the shape of the indenter is different from the spherical or conical indenter, and the cylindrical flat-bottomed indenter. Therefore, PDC drilling rock fragmentation mechanism can not simply be pressure molded into a spherical, conical or cylindrical flat bottom conclusions analysis, and need for the a specific oblique PDC shape, combined with a specific rock crushing way analysis.Through the stress analysis for the PDC pressed into cutting rock, the contact pressure between the single PDC piece and rock is detailed derivation by the use of contact mechanics theory, and the model between the role of the load and pressure with the rock depth is established. The relational model about the contact interaction of the combination of different sizes, shapes PDC piece and different geometry PDC drill is established, and the influencing factors and laws of the contact pressure is analyzed. On this basis and based on the relevant rock strength criteria, the thesis has analyzed the crack initiation and fracture plane position in front of the rock crusher, while the PDC is drilling in the rock with oblique loads, and established a theoretical model of PDC drilling rock crushing conditions.Based on the mechanical properties data of the test rock and PDC, some indoor tests of PDC pressed into cutting rock were done with the different sizes and the number of PDC. Then a PDC bit was designed, and bench test was drilling. According to the test data, the correlation between various parameters and laws were studied, and the results were compared with the theoretical research.This thesis have created a variety of different shapes and sizes PDC and the different structure of PDC bits pressed into cutting rocks geometric model by the Design Modeler of the Ansys Workbench, then used the Static Structural or Transient Structural module for finite element analysis, post-processing and analysis. Finally, the various parameters were designed and analyzed by the Design Explorer module. The chapters are as follows:The first chapter described the meaning and purpose of this thesis, and reviewed the theoretical research status and trends of rock crushing force and PDC, and elaborated the research content and methods of the thesis.The second chapter is a study on PDC stress analysis by theoretical methods, to figure out the influencing factors of the contact pressure, and the relationship between the contact pressure with the forces of the PDC composite piece.There are two contact surfaces between PDC and rock, when shaping PDC pressed into cutting rock. This thesis derived the contact pressure of the contact surface by contact mechanics theory. The relationship with the PDC pressure acting on the PDC and the depth cutting into the rock was analyzed by the limit force equilibrium condition, and this indicated that the depth of the contact pressure and the pressure into the rock is a non-linear proportional relationship. Through the force analysis of PDC bits, to draw the relationship between the pressure of drill shaft and the torque with a single PDC force and drilling machinery speed, etc.The third chapter is an analysis of PDC pressed into cutting rock crushing. According to the theory of the calculated contact pressure, the conditions of PDC pressed into the rock crushing were analyzed through the rock compressive mechanical properties. Then combination of rock strength theory, the rock crack initiation, development conditions and macro-cracking surface, while PDC pressure into cutting rock, were analyzed, and obtained the condition model of PDC drilling rock broken. So qualitative analysis of the PDC drilling rock crushing process was carried on.The contact pressure must be inevitably affect when non shaping PDC pressed into the rock, because of the shape and size variation of the contact surface between the PDC and the rock. So the contact pressure of the contact surface between a small part cutting PDC and rock was analyzed still by the relevant contact mechanics theory, and the results were compared with shaping PDC contact pressure formula. These show that the calculating form of the contact pressure between the PDC and rock was unchanged, because the form of the PDC pressed into cutting rock fragmentation unchanged, but the correlation coefficient should be related to the geometric characteristics of the PDC. Then the geometric characteristics factors influencing the contact pressure of the PDC were analyzed.The fourth chapter is about the study and the analysis of the laboratory test results, and the purpose is to verify the conclusions of the theoretical research. The mechanical properties of the test rock and PDC were trials test by pilot plant, and the test data may as the data foundation of micro-drill test and numerical analysis.Several physical models of some shaping and non-Shaping PDC pressed into cutting rock were designed, and micro-drilling tests were trialed. According to the results of various tests, the factors of impact of the PDC drilling rock crushing effect were analyzed. According to the conclusions of the preliminary research, a PDC bit was designed and manufactured, and bench test was trialed, and the test parameters and effects were analyzed.Chapter V, on the basis of theoretical and experimental research, numerical analysis of the PDC pressed into cutting rock was executed. Several simulation geometry models were designed. The first model was a single shaping PDC pressed into cutting rock, and the second model was a single non-shaping PDC pressed into cutting rock, and the third model was combination of PDC constituted by two or six PDC, which pressed into cutting rock. The geometry factors of cutting angle and torsion angle etc. were considered in the simulation analysis process. The correlation between the various parameters was analyzed by the Design Explorer of ANSYS. The nephogram of the stress and deformation and curve of the various parameters correlation showed that the size effect of the PDC to the contact pressure and deformation on the rock have a greater impaction, and the theoretical curves and numerical analysis curve is more in line with, this also showed that the theoretical analysis is definite.Chapter VI is the concluding chapters, which summarizes the relevant conclusions of the full text, and analyzes and outlooks the questions and requires to continue in-depth this research.In short, through theoretical derivation modeling, test analysis and the numerical analysis, the mechanism of the PDC pressed into cutting rock crushing achieved certain results.更多还原