针对硬地层的单牙轮-PDC双级钻头的破岩特性研究

发布时间：2018-05-04 06:17

本文选题：双级钻头 + 分级破岩　；参考：《西南石油大学》2017年硕士论文

【摘要】：随着我国油气勘探开发工作逐渐向深井、超深井发展,以及大直径井段增多,传统的牙轮钻头和PDC钻头在钻进过程中,破岩效率低,钻速慢且寿命短,无法满足钻井提速增效的要求,提高深井、大直径井段的机械钻速已成为当前国内外油气钻井一个急需解决的主要问题。单牙轮-PDC双级钻头作为一种新型钻头,采取分级破岩的方式,为实现硬地层钻井提速增效提供了新思路。本文基于弹塑性力学、岩石力学以及仿真研究的方法,研究了单牙轮-PDC双级钻头与岩石的相互作用规律及破岩特性,对于掌握单牙轮-PDC双级钻头破岩特性以指导其结构设计、加快其推广应用具有重要工程意义。本论文的主要内容及取得的成果如下:(1)开展了双级钻头破岩机理与切削齿受力分析。运用弹塑性力学、岩石力学,分析了双级钻头的破岩机理及切削齿受力情况,从破岩机理的角度得出了双级钻头提高机械钻速的力学机理,并为后续章节的仿真分析奠定了理论基础。(2)开展了阶梯井底应力场的研究。运用数值模拟的方法,建立了阶梯井底受力模型,分析了阶梯井底的应力状态,并对比分析了钻扩比和两级破岩结构相对高度对阶梯井底的应力场影响,结果表明:阶梯井底领眼井壁及领眼井底应力释放明显,可钻性强;钻扩比越小,领眼井壁应力释放更加充分,岩石可钻性更强,且钻扩比越小,领眼井壁应力释放区域更大;两级破岩结构相对高度越小,领眼井壁岩石应力释放越充分,当相对高度超过一定数值后,领眼井壁的应力释放区域将延伸到井眼外围,不利于井壁的稳定性,也会使钻头破岩过程中能量过多的被耗散。(3)开展了单牙轮-PDC双级钻头与常规PDC钻头、双级PDC钻头的破岩仿真对比。建立了单牙轮-PDC双级钻头、常规PDC钻头和双级PDC钻头的破岩模型,通过分析,结果表明:单牙轮-PDC双级钻头作用下岩石的应力水平低于常规PDC钻头,能更容易破碎岩石;双级钻头扭转振动低于常规PDC钻头和双级PDC钻头,振动幅值分别降低了 75%和30%,扭矩均值分别降低了 65%和56%;双级钻头对岩石的轴向冲击作用高于常规PDC钻头和双级PDC钻头,有更高的破岩效率。(4)开展了钻扩比与两级破岩结构相对高度对双级钻头破岩特性的影响研究。建立了三种钻扩比的双级钻头破岩模型和三种相对高度的双级钻头破岩模型,通过破岩对比分析,结果表明:在两级破岩结构相对高度不变的条件下,钻扩比越小,双级钻头在钻进方向对岩石的冲击作用越大,破岩效率越高,机械钻速越快,但同时破岩所需的扭矩越大;在钻扩比不变的条件下,相对高度越小,两级破岩结构联动性越强,相互促进作用越显著,在钻进方向对岩石的冲击作用越大,破岩效率越高,机械钻速越快,但同时破岩所需的扭矩越大。
[Abstract]:With the development of oil and gas exploration and development to deep wells, ultra-deep wells and the increase of large diameter wells in China, the traditional cone bit and PDC bit have low rock breaking efficiency, slow drilling speed and short life in the drilling process. It can not meet the requirements of increasing drilling speed and increasing efficiency. It has become an urgent problem for oil and gas drilling at home and abroad to improve the mechanical drilling speed of deep wells and large diameter wells. As a new type of bit, the single-cone -PDC double-stage bit adopts the method of breaking rock by stages, which provides a new way to increase the speed and increase the efficiency of drilling in hard formation. Based on the methods of elastic-plastic mechanics, rock mechanics and simulation, this paper studies the interaction law and rock breaking characteristics of single-cone -PDC double-stage bit with rock, which can guide its structural design by mastering the rock breaking characteristics of single-cone -PDC double-stage bit. It is of great engineering significance to accelerate its popularization and application. The main contents and results of this paper are as follows: 1) the rock breaking mechanism and cutting tooth force of two-stage bit are analyzed. By using elastoplastic mechanics and rock mechanics, the rock breaking mechanism and cutting tooth force of two-stage bit are analyzed, and the mechanical mechanism of two-stage bit to increase mechanical drilling rate is obtained from the angle of rock breaking mechanism. The theoretical basis for the simulation analysis of the following chapters is established. (2) the study of the bottom-hole stress field is carried out. By means of numerical simulation, the stress model of the bottom hole is established, and the stress state of the bottom hole is analyzed, and the influence of the ratio of drill expansion and the relative height of the two-stage rock breaking structure on the stress field of the bottom hole is compared and analyzed. The results show that the stress release is obvious and the drillability is strong, the lower the drilling expansion ratio, the more fully the stress release and the stronger drillability of rock, and the smaller the drilling-expansion ratio, the larger the stress release area. The smaller the relative height of the two-stage rock breaking structure, the more fully the rock stress release from the collar wall. When the relative height exceeds a certain value, the stress release area of the collar wall will extend to the outside of the well, which is not conducive to the stability of the borehole wall. It will also cause excessive energy dissipation in the rock breaking process.) the rock breaking simulation of single cone PDC double stage bit and conventional PDC bit and two stage PDC bit is carried out. The rock breaking model of single-cone -PDC double-stage bit, conventional PDC bit and double-stage PDC bit is established. The results show that the stress level of rock under the action of single-cone -PDC double-stage bit is lower than that of conventional PDC bit, and the rock can be broken more easily. The torsional vibration of two-stage bit is lower than that of conventional PDC bit and two-stage PDC bit, the amplitude of vibration is reduced by 75% and 30%, the mean of torque is reduced by 65% and 56%, and the axial impact of two-stage bit to rock is higher than that of conventional PDC bit and two-stage PDC bit. The influence of the ratio of drill expansion and the relative height of two-stage rock breaking structure on the rock breaking characteristics of two-stage bit is studied. The rock breaking model of three kinds of drill expansion ratio and the rock breaking model of two stage bit with relative height are established. The results show that the ratio of drill expansion is smaller under the condition that the rock breaking structure of two stages is relatively high constant. The greater the impact on the rock in the drilling direction, the higher the rock breaking efficiency, the faster the mechanical drilling speed, but the greater the torque required to break the rock at the same time; under the condition of constant drilling expansion ratio, the lower the relative height, the stronger the linkage of rock breaking structure between the two levels. The more significant the interaction is, the greater the impact on rock is in the drilling direction, the higher the rock breaking efficiency is, the faster the mechanical drilling speed is, but the more torque is required to break the rock at the same time.
【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】：TE921.1

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