RWD随钻扩眼钻进的破岩机理研究

RWD随钻扩眼使钻井和扩眼过程一次完成，并满足大部分特定井身轨迹严格控制的要求，具有工具结构简单，无活动部件，扩眼尺寸稳定规则的特点，是解决复杂深井阻卡、非常规井身结构应用和提高固井质量的有效手段。随钻扩眼过程中，扩眼器与所扩地层之间的岩石力学耦合作用对随钻扩眼钻进破岩效果和扩眼器、钻柱的优化设计等至关重要。为此，建立了弹塑性有限元力学分析模型，运用莫尔－库仑强度准则，用数值分析的原理和方法模拟了随钻扩眼时扩眼器破岩的力学机理。并对井眼围岩变形和应力分析及强度进行了研究，为研究随钻扩眼的破岩规律和对扩眼器进行改进提供了一种方法和研究的基础。

STUDY ON ROCK-CUTTING MECHANISM OF REAMING WHILE DRILLING (RWD)

RWD is to ream while drilling, no need to drill a pilot hole and then enlarge the hole later with a reamer. It can complete the drilling and reaming in one trip, and meet the requirements of strict control of most special wellbore trajectories, with characteristics of simple tool structure, no running parts, stable and regular reamed hole sizes. It's an effective means to solve the sticking in deep wells, to apply non-conventional casing programs, to improve the cementing quality, and to reduce the drilling costs. During reaming while drilling, the mechanical coupling effects between the reamer and the reamed formations are critical to rocking-cutting efficiency of the RWD, and the optimization design of the reamer and the drilling string. Therefore, an elastoplasticity FEA model was established based on the Mohr-Coulomb rule, to simulate the mechanical mechanism of the rock-cutting action of RWD. Moreover, study is made on deformation and stresses of adjacent rocks, which will provide a basis for research on rock-cutting rules of RWD, and improvement of reamers.