柔性钻具组合防斜打快机理研究

发布时间：2018-04-10 22:04

本文选题：井底应力场 + 柔性钻具组合　；参考：《西南石油大学》2015年硕士论文

【摘要】：柔性钻具组合是最近提出来的一种钻具组合,并在油田某些区块收到很好的应用效果,该钻具组合安装有柔性接头,通过稳定器的配合,能改变钻头轴线的偏转方向和受力状态。柔性接头钻具组合防斜打快机理研究是基于柔性钻具组合在易斜地层中的应用,本文从以下几个方面开展了工作： 1.采用有限元法建立了直井的井底应力场分析模型,分析了不同因素下各向异性地层井底应力场的分布差异,探讨了不同因素对井底应力场及井眼轨迹的影响。研究表明,不同节理面倾角岩体发生应力集中的位置受节理面与井眼相交的影响较大,井眼内的液柱压力越小,井底岩石越容易受到拉应力破坏,易产生偏斜；节理面间距越小,应力集中发生次数越多,岩石更容易破坏,产生偏斜；水平主应力的大小和方向会改变井眼偏斜方向；大尺寸井眼中,井底井眼附近岩石更容易发生破坏；考虑钻压作用的井底井周附近的岩石应力增大,更容易发生应力集中现象。 2.从静力学上分析了柔性钻具组合的防斜原理,其降斜的条件是柔性接头的中心位于井眼轴线上,主要靠加压改变钻具变形产生的挠曲方向,使近钻头稳定器紧贴于上井壁,在加压钻进中实现钻头偏转角下倾,产生降斜趋势；建立了柔性钻具组合静力学分析模型,实例计算表明,柔性钻具组合的钻头降斜力随钻压和井斜角增大而增大,在井眼产生井斜的条件下,相比常规钟摆钻具组合具有更好的防斜性能。 3.基于地层和钻头的相互作用模型,考虑钻头各向异性和地层各向异性的影响,采用“井斜趋势角”综合指标对防斜钻具组合的防斜性能进行分析；实例计算表明,在地层特性和钻头特性相同条件下,随着钻压的增大,柔性钻具的井斜趋势角明显大于钟摆钻具组合,其降斜趋势更明显,在大钻压下能更好地发挥其防斜性能。 4.运用转子动力学理论和虚功原理建立了底部钻具组合的动力学分析模型,以距离钻头较近的带柔性接头的钻铤段为研究对象,探讨分析了钻压和井斜影响下的钻铤形心涡动规律；动力学仿真结果表明,在钻井液中涡动特征为向前涡动,井斜角越大,钻铤形心偏向下井壁的运动越明显；适当的增加钻压,对于钻井过程中的防斜和纠斜是有利的；钻压波动频率较大时,影响钻头对上下井壁的切削位置和程度。
[Abstract]:The flexible drilling pipe assembly is a kind of drilling tool combination that has been put forward recently, and has received very good application effect in some blocks of the oil field. The assembly is equipped with flexible joint, which is matched by stabilizer.The deflection direction and force state of the bit axis can be changed.Based on the application of flexible drilling tool combination in easy slant formation, the research on the mechanism of flexible joint drilling tool combination is based on the application of flexible drilling tool combination in easy slant formation. This paper has carried out the work from the following aspects:1.The analysis model of bottom hole stress field in vertical well is established by using finite element method. The distribution difference of bottom hole stress field in anisotropic formation under different factors is analyzed, and the influence of different factors on bottom hole stress field and borehole trajectory is discussed.The results show that the position of stress concentration in inclined rock mass with different joint planes is greatly affected by the intersection of joint plane and borehole, and the smaller the pressure of liquid column in borehole, the easier the rock in bottom hole to be destroyed by tensile stress and inclined.The smaller the joint plane spacing, the more stress concentration occurs, the more easily the rock will be destroyed, the more inclined the horizontal principal stress will be, and the more easily the rock near the bottom hole will be destroyed in the large size well.The stress concentration is more likely to occur when the rock stress around the bottom hole increases with the consideration of drilling pressure.2.In this paper, the anti-deviation principle of flexible drilling tool combination is analyzed statically. The condition of reducing deviation is that the center of flexible joint is located on the shaft line, and the deflection direction caused by the deformation of the drill tool is mainly changed by pressure, which makes the near bit stabilizer stick close to the upper shaft wall.A static analysis model of flexible drilling tool combination is established, and the calculation results show that the deflecting force increases with the increase of drilling pressure and inclined angle.Under the condition of borehole deviation, it has better anti-deviation performance than conventional pendulum drilling tool combination.3.Based on the interaction model of formation and bit, considering the influence of anisotropy and anisotropy of drill bit, the comprehensive index of "well inclination trend angle" is used to analyze the anti-deviation performance of anti-slant drilling tool combination.Under the same conditions of formation characteristics and bit characteristics, with the increase of drilling pressure, the inclined angle of flexible drilling tools is obviously larger than that of pendulum drilling tool combinations, and the tendency of slanting reduction is more obvious, and the anti-deviation performance of flexible drilling tools can be better brought into play under high drilling pressure.4.Based on the rotor dynamics theory and virtual work principle, the dynamic analysis model of bottom drill tool combination is established. The drill collar section with flexible joint near the bit is taken as the research object.The dynamic simulation results show that the vortex characteristic of drill collar is forward vortex in drilling fluid, and the bigger the angle of well is, the more obvious the movement of drill collar center is under the lower shaft wall deviation, and the more inclined angle is, the more obvious the movement of drill collar center is under the influence of drilling pressure and well deviation, and the dynamic simulation results show that the vortex characteristic is forward vortex in drilling fluid.A proper increase of drilling pressure is beneficial to the prevention and correction of deviation during drilling, and when the frequency of drilling pressure fluctuation is large, it will affect the cutting position and degree of drill bit to the upper and lower shaft wall.
【学位授予单位】：西南石油大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TE921

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