混合式单牙轮钻头破岩数值模拟及实验研究

发布时间：2018-03-17 13:08

本文选题：单齿破岩　切入点：混合式单牙轮钻头　出处：《西南石油大学》2017年硕士论文　论文类型：学位论文

【摘要】：单牙轮钻头因其在钻进过程中遭受的冲击载荷小,且轴承寿命长而被广泛应用于深井和小井眼钻井中。但是目前油田广泛使用的球形单牙轮钻头,其牙齿在钻进硬地层和高研磨性地层中的先期磨损和折断比较严重,造成其寿命降低。而最近几年研发设计的异形单牙轮钻头虽在牙齿磨损方面做出了改进,但是它在钻进过程中的侧向力较大,钻头偏磨较为严重。为了克服单牙轮钻头的这些缺陷,本文结合单牙轮钻头和PDC钻头破岩特点,设计了一种新型的单牙轮钻头,并对其钻进过程进行了台架实验和数值模拟研究,具体内容如下:(1)本文对单牙轮钻头的结构和性能特点进行了阐述,详细介绍了单牙轮钻头的几何学基本方程及钻头失效形式,详细分析了地层特性、钻压及转速对单牙轮钻头钻进的影响规律。(2)在考虑地层渗透性的作用下,研究了单牙轮钻头钻进过程,近井底地层的孔隙压力变化。根据渗流力学原理,建立了微分方程并求解得到井底孔隙压力分布。在充分考虑井底受力的条件下,建立了适用于不同渗透率储层的单牙轮钻头单齿破岩数学模型,并进行了应用分析。结果表明:1)低渗地层,钻井液液柱压力和孔隙压力对牙齿钻进的影响较小;2)高渗地层相比低渗地层,牙齿钻进对垂向载荷的变化更加敏感,故在渗透率较高的地层,增加牙齿的垂向载荷能够有效地提高钻头的破岩效率;3)相对于低渗透地层,地层渗透率较高时,减小名义压差对提高钻速更有效果。(3)基于已有的单牙轮钻头结构设计原理,本文分别对现有的牙掌和牙轮结构进行了改进,设计了一种混合式单牙轮钻头(该钻头结构已经申请了发明专利并获得授权一种混合式单牙轮钻头201410011199.8);(4)设计台架实验,对混合式、球形和异形单牙轮钻头的轴向力、侧向力、进尺位移及岩石破碎量等参数进行测量,并将三者的这些参数进行对比分析,结果表明混合式单牙轮钻头的侧向力比较小,钻进稳定性比异形单牙轮钻头好,机械钻速相比球形单牙轮钻头高;(5)建立了混合式单牙轮钻头与岩石互作用有限元模型并对其破岩进行了数值模拟。通过对比实验和模拟的钻压时程曲线和进尺量验证了数值模拟的可靠性。通过实验和仿真数据的对比,详细分析了混合式单牙轮钻头的井底模式,对其各部分牙齿的运动形式有了初步的认知,然后利用仿真数据分析了各齿圈牙齿的载荷的分布以及其随钻压的变化,得出牙掌内边缘PDC齿和牙轮大端牙齿是混合单牙轮钻头的主要切削部位,且切削齿载荷最大值出现在牙轮大端。实验和数值模拟结果表明:该混合单牙轮钻头结构设计合理,钻头破岩效率得到了一定的提高,侧向力相对异形单牙轮钻头得到了改进。
[Abstract]:Single cone bit is widely used in deep well and small hole drilling because of its small impact load and long bearing life, but spherical single cone bit is widely used in oil field at present. The tooth wear and break in hard formation and high abrasive formation are serious, which reduces its life. Although the special-shaped single cone bit developed in recent years has been improved in tooth wear, In order to overcome these defects of single cone bit, a new type of single cone bit is designed based on the characteristics of single cone bit and PDC bit. In this paper, the structure and performance characteristics of single cone bit are described, and the geometric basic equation and failure form of single cone bit are introduced in detail. The effects of formation characteristics, drilling pressure and rotational speed on drilling of single cone bit are analyzed in detail. Considering the permeability of formation, the drilling process of single cone bit and the change of pore pressure near bottom hole are studied. According to the principle of percolation mechanics, The differential equation is established and the distribution of bottom hole pore pressure is obtained. The mathematical model of single tooth breaking rock of single cone bit suitable for different permeability reservoirs is established under the condition of fully considering the stress on bottom hole. The results show that the influence of drilling fluid column pressure and pore pressure on tooth drilling is smaller in low permeability formation than in low permeability formation, and tooth drilling is more sensitive to the change of vertical load than that in low permeability formation. Therefore, in the formation with high permeability, increasing the vertical load of the teeth can effectively improve the rock breaking efficiency of the drill bit (3) compared with the low permeability formation, when the formation permeability is higher, It is more effective to reduce nominal pressure difference to increase drilling speed. (3) based on the structural design principle of single cone bit, the existing palms and wheel structures are improved respectively in this paper. A hybrid single-cone bit (the structure of which has been patented and authorized to be used in 201410011199.8) is designed to design a bench test for the axial and lateral forces of the hybrid, spherical and special-shaped single cone bit. The parameters such as advance displacement and rock breakage are measured and compared with each other. The results show that the lateral force of the hybrid single cone bit is smaller and the drilling stability is better than that of the special-shaped single cone bit. A finite element model of the interaction between a hybrid single cone bit and a rock is established and its rock breaking is simulated numerically. The time history curve of drilling pressure and the feed rate are compared with each other. The reliability of numerical simulation is verified. The bottom hole mode of hybrid single-cone bit is analyzed in detail, and the movement form of each part of the bit is preliminarily recognized. Then, the load distribution of the teeth in each gear ring and its variation with drilling pressure are analyzed by using the simulation data. The results show that the PDC teeth and the large end teeth are the main cutting parts of the hybrid mono-cone bit, and the maximum load of the cutting teeth appears at the large end of the cone. The experimental and numerical simulation results show that the structure of the hybrid single-cone bit is reasonable. The rock breaking efficiency of bit is improved to some extent, and the lateral force is improved relative to special-shaped single cone bit.
【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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