The Research on the Biggest Borehole Curvature that Allowed through for theRotating Casing

With the development of highly-deviated well cementing techniques, rotating casing cementingtechnology has got more and more attention. The rotating casing technique can improve thedisplacement efficiency of cement paste, and then enhance the quality of well cementation. In the stucksection, the rotating casing can redress the well to make the casing run sequentially. The casingendures shear stress in rotating, besides axial stress, bending stress, circumferential stress and radialstress which are produced by inside and outside casing pressure stress. These forces make it morecomplicated when calculate the maximum curvature in rotating condition than that without rotation.The paper, by analyzing the casing stresses in rotating condition, assumes a stress model of the casinginfinitesimal for rotating casing. It puts forward the calculation method for the maximum allowableborehole curvature in casing bucking deformation, or when casing couplings and thread seal fail underrotating condition. It also determines the biggest borehole curvature that allowed though, laying a basefor the design and construction of the highly-deviated well casing.