振动冲击下硬脆性岩石断裂机制研究

发布时间：2018-03-23 22:40

本文选题：冲击振动　切入点：硬脆性岩石　出处：《东北石油大学》2017年硕士论文

【摘要】：随着油气资源勘探开发的不断深入,钻井的难度日渐增加,井深慢慢从浅层向深层甚至超深层延伸,岩石破碎的难度也逐步加大,岩石破碎效率越来越低,钻井周期不断加长,钻井成本不断提高,急需新的高效破岩技术来提高破岩效率,提高钻井速度。因此在各种钻井技术中高效钻井破岩技术就凸显了自身的重要性。目前国内外学者对冲击振动钻井技术进行了研究,从工程技术角度揭示了其提高机械钻速的机理,但振动冲击作用下的理论机理研究较少,因此,本文在考虑岩石重力的基础上针对高频振冲击钻头下岩石振动响应及破碎机理进行研究。基于振动理论,考虑冲击钻井的实际情况建立了考虑岩石重力的物理模型,并利用重整化方法求解了数学模型,分析了岩石在振动冲击下的响应机制。同时建立了脆性岩石的动态断裂模型,建立了岩石振动冲击下响应与破碎的直接关系,进而通过各参数的分析比较确定各参数对岩石破碎鲜果的影响,为现场振动破岩提供理论基础。取得了以下的研究结论:(1)考虑岩石重力,将理想岩石假设为多个带重量的弹簧,建立了岩石振动模型,应用重整化方法求解出了岩石固有频率的计算模型,进而给出了岩石的振动位移的计算模型。(2)基于岩石的振动位移的计算模型,结合岩石动态断裂准则,给出了岩石裂纹动态断裂的极限位移。该极限位移是个范围,由上下限构成,分别表示岩石裂纹在受拉和受压两种情况下动态断裂时裂纹张开和闭合程度。(3)完成了振动冲击作用下岩石响应的数值分析及冲击振动作用下钻头破岩的室内实验研究研究:分析了岩石密度,岩石弹性模量对岩石振动基频的影响;分析了振动冲击载荷振幅对冲击作用下岩石产生的最大位移和最大对等应力的影响;分析了不同冲击频率对振动冲击下岩石产生的最大位移的影响,并与岩石固有频率值进行比较。(4)岩石的密度、岩石的刚度、钻头冲击力的大小、冲击的频率等对钻头下岩石振动有影响。岩石的密度越小,刚度越小,钻头高频冲击的冲击力越大,岩石的振动幅度越大,振动速度也越快。(5)岩石存在一个固有频率,其与岩石刚度正相关,与岩石密度负相关。钻头高频振动冲击频率越接近岩石的固有频率,岩石的振动越剧烈。当钻头高频振动频率和岩石固有频率相等时,岩石振动幅度和振动速度最大,即达到了共振。本文的研究对振动冲击钻井在现场的实施应用具有一定的指导意义和使用价值。
[Abstract]:With the deepening of exploration and development of oil and gas resources, the difficulty of drilling is increasing day by day, the depth of well extends slowly from shallow layer to deep layer or even super deep layer, the difficulty of rock fragmentation is gradually increased, the efficiency of rock fragmentation is becoming lower and lower, and the drilling cycle is increasing. Drilling costs are increasing, and new and efficient rock breaking techniques are urgently needed to improve rock breaking efficiency. Therefore, the high efficiency drilling and rock breaking technology in various drilling technologies has highlighted its own importance. At present, the impact vibration drilling technology has been studied by domestic and foreign scholars. From the point of view of engineering technology, the mechanism of increasing mechanical drilling speed is revealed, but the theoretical mechanism under vibration shock is less studied, so, On the basis of considering rock gravity, this paper studies rock vibration response and breaking mechanism under high frequency vibration impact bit. Based on vibration theory, a physical model considering rock gravity is established considering the actual condition of impact drilling. The mathematical model is solved by renormalization method, and the response mechanism of rock under vibration shock is analyzed. At the same time, the dynamic fracture model of brittle rock is established, and the direct relation between response and breakage under vibration shock of rock is established. Furthermore, through the analysis and comparison of various parameters, the influence of each parameter on the broken fresh fruit of rock is determined, which provides a theoretical basis for rock breaking in situ vibration. The following conclusions are obtained: 1) considering the gravity of the rock, the ideal rock is assumed to be a spring with multiple weights. The rock vibration model is established, and the natural frequency calculation model of rock is solved by using renormalization method. Furthermore, the calculation model of rock vibration displacement is given, which is based on rock vibration displacement and combined with rock dynamic fracture criterion. The limit displacement of dynamic fracture of rock crack is given. The limit displacement is a range and consists of upper and lower limits. The results show that the crack opening and closing degree of rock crack under dynamic fracture under tension and compression respectively has completed the numerical analysis of rock response under vibration shock and the laboratory experiment of bit breaking under shock vibration. Research: the density of rock is analyzed. The influence of elastic modulus of rock on the fundamental frequency of rock vibration and the effect of amplitude of vibration shock load on the maximum displacement and maximum equivalent stress of rock under impact are analyzed. The influence of different impact frequencies on the maximum displacement of rock under vibration shock is analyzed, and the density of rock, the rigidity of rock and the impact force of bit are compared with the natural frequency of rock. The lower the density of rock, the smaller the stiffness, the greater the impact force of high frequency impact, the larger the amplitude of rock vibration and the faster the vibration velocity of rock. It is positively correlated with rock stiffness and negatively correlated with rock density. The higher the impact frequency of the bit is, the more intense the rock vibration is. When the bit high frequency vibration frequency is equal to the rock natural frequency, The vibration amplitude and velocity of rock are the largest, that is to say, resonance is achieved. The research in this paper has certain guiding significance and practical value for the application of vibration impact drilling in the field.
【学位授予单位】：东北石油大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TE21

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