ABSTRACT

The oilwell drilling fluid flows cause viscous and hydrodynamic forces on drill strings. This effect is ignored or treated as a constant in most drill string models. The present study introduces mathematical models for lateral vibration damping and axial drag forces that are employable in lumped segment drill string models. First, the variables to which drilling fluid-generated forces are most sensitive were identified and the Response Surface Method was applied to design the experiment matrix. The lateral vibration-damping experiments, which were validated using a scaled-down physical model, and the axial drag experiments were done using Fluid-Structure Interaction simulations. The results were statistically analysed to acquire the models and were implemented in a 3D lumped segment bond graph developed using the Newton-Euler formulation and body-fixed coordinates. The results indicate a considerable effect of the extended treatment of damping and axial drag on bending moment fluctuation, wellbore interactions, and weight on bit.

摘要

油井钻井液流动对钻柱产生粘性和流体动力。在大多数钻柱模型中，这种影响被忽略或视为常数。本研究介绍了可用于集总段钻柱模型的横向振动阻尼和轴向阻力的数学模型。首先，确定钻井液产生的力最敏感的变量，并应用响应面法设计实验矩阵。横向减振实验使用按比例缩小的物理模型进行验证，轴向阻力实验使用流固耦合仿真进行。对结果进行统计分析以获取模型，并在使用 Newton-Euler 公式和身体固定坐标开发的 3D 集总段键图中实施。结果表明，阻尼和轴向阻力的扩展处理对弯矩波动、井筒相互作用和钻压有相当大的影响。