径向水平井弯曲转向机构影响因素仿真研究

针对径向水平井钻进中钻杆弯曲转向前进运动困难的问题,通过建立弯曲转向机构仿真有限元模型,对其主要影响因素:滑道轨迹曲率、间隙、工作压力、滚轮形状与位置和钻杆壁厚等用ANSYS软件进行仿真研究。研究表明:影响截面变形的主要因素是滑道曲率的改变和滑道摩擦因数,钻井失败时钻杆所受阻力的增大不是因为升高工作压力导致截面变形过大与滑道干涉所致,钻杆经校直段,钻头中轴线与校直中心线存在一定的角度,即钻杆的前进轨迹就会偏离理论值,或与地层干涉,或可能再次发生弯曲变形;另一主要原因是转向器滑道工作恶化。增加钻杆壁厚,降低工作压力和滑道摩擦因数,设计合理弯曲转向机构是解决问题的关键。

Simulation on the influencing factors of bending steering mechanism used in radial horizontal wells

In consideration of the problem of drill pipe bending steering in radial horizontal well drilling, ANSYS software is used to simulate its major influencing factors, such as slideway trajectory curvature, clearance, working pressure, roller shape and position and thickness of drill pipe by establishing a finite element model for the bending steering mechanism. It shows that the major factors influencing sectional deformation include the changes of slideway curvature and its friction coefficient. The increase of drag applied on the drill pipe as drilling failure occurs is not induced by excessive sectional deformation because of high working pressure. In the radial straightening section of the drill pipe, there exists a certain angle between drill bit central axial line and straightening center line, that is the forward trajectory of drill pipe deviating from theoretical value or possibly interference in. formation or bending deformation are induced again. The other major influencing factor is the extreme working condition. The key for solving the problem is to increase the drill pipe thickness, reduce working pressure and slideway friction coefficient, and rationally design the bending steering mechanism.