钻柱固液耦合横向振动研究

发布时间：2019-02-23 16:24

【摘要】：随着油气开采量的加大和油气储量的减小,为了提高油气井的采收率,同时降低钻井的成本,水平井技术成为现代钻井技术中一项十分重要的钻井技术,但因为水平井钻进过程中,钻柱易偏离自己的旋转中心,导致横向振动,而严重的钻柱振动将导致钻具产生逐渐扩展的脆性裂纹,导致最终断裂等严重事故。所以,探讨钻柱横向振动是非常有意义的。本文针对钻柱共振导致的钻具产生逐渐扩展的脆性裂纹,最终导致其断裂的问题。以岳10X-A1水平井直井段钻柱为研究对象,考虑钻柱外钻井液密度比钻柱内钻井液密度大这一重要因素,采用流体数值计算软件,分别对钻柱内钻井液进行K-ε湍流模型分析,对钻柱环空段钻井液进行离散相模型分析,得到钻柱内壁压力及外壁压力随井深变化的曲线,从钻柱内、外壁压力曲线可以看出,密度、粘度、流速中任一因素的变化均会引起压降变化,由流体力学理论可知,管路中能量的消耗会产生压降,而能量的消耗是由水头损失引起的,水头损失又主要分为沿程水头损失和局部水头损失,根据管路沿程水头损失和局部水头损失公式可知,密度、粘度、流速越大,压降越大,且当除管路长度之外的因素均不变时,压降与管路长度成线性关系,故通过计算建立了钻柱内壁压力及外壁压力随井深变化的函数;再根据钻井实钻数据,基于动力学理论,应用ANSYS软件建立水平井直井段钻柱横向振动模型,考虑钻柱内外不同密度钻井液对钻柱振动的作用,将钻井液压力分布以函数加载的方式加载到有限元模型上,通过模态分析,获得了钻井液密度、钻井液粘度、钻井液流速、钻压对钻柱横振固有频率的影响规律,得到钻井液密度、粘度、流速、钻压增大时,钻柱横振固有频率均大致减少,从而为水平井直井段施工提供一定的实际指导意义。
[Abstract]:With the increase of oil and gas exploitation and the decrease of oil and gas reserves, horizontal well technology has become a very important drilling technology in modern drilling technology in order to improve oil and gas recovery and reduce drilling cost. However, during horizontal well drilling, the drill string is easily deviated from its rotation center, which leads to lateral vibration, and the serious vibration of drill string will lead to the gradual propagation of brittle cracks in the drill tool, resulting in the final fracture and other serious accidents. Therefore, it is very meaningful to study the lateral vibration of drill string. In this paper, the brittle crack of drill pipe due to the resonance of drill string is gradually extended, which leads to the fracture of drill pipe. Taking the drill string in the straight section of Yue 10X-A1 horizontal well as the research object, considering the important factor that the drilling fluid density outside the drill string is higher than that in the drill string, the fluid numerical calculation software is used. The K- 蔚 turbulence model was used to analyze the drilling fluid in the drill string, and the discrete phase model was used to analyze the drilling fluid in the annulus of the drill string. The curves of the inner wall pressure and the outer wall pressure of the drill string changing with the depth of the well were obtained. As can be seen from the pressure curve of the outer wall, any change in density, viscosity and flow rate will cause pressure drop. According to the theory of fluid mechanics, the energy consumption in the pipeline will produce pressure drop, and the energy consumption is caused by the loss of water head. The head loss is mainly divided into the head loss along the path and the local head loss. According to the formula of the head loss along the pipeline and the local head loss, the greater the density, viscosity and velocity, the greater the pressure drop. The pressure drop is linearly related to the length of the pipe when all the factors except the length of the pipe are invariable, so the function of the inner wall pressure and the outer wall pressure of the drill string with the depth of the well is established by calculating. Based on the drilling data and dynamic theory, the lateral vibration model of drilling string in horizontal well is established by using ANSYS software. The effect of drilling fluid with different density inside and outside the drill string on the vibration of drill string is considered. The pressure distribution of drilling fluid is loaded into the finite element model by function loading. Through modal analysis, the effects of drilling fluid density, drilling fluid viscosity, drilling fluid velocity and drilling pressure on the natural frequency of drilling string transverse vibration are obtained. When the drilling fluid density, viscosity, flow rate and drilling pressure increase, the natural frequency of horizontal vibration of drill string is reduced, which provides some practical guidance for horizontal well vertical section construction.
【学位授予单位】：长江大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TE921.2

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