Design Of A High Pressure Bearing Assembly For Rotating Control Head

Underbalanced drilling is an advanced technology developed in these years. It has many advantages than regular drilling technologys. The oil fields in China all focus on the development and using of this technology. But its pivotal part—bearing assembly, depends totally on importation. In order to develop our own bearing assembly which can work at the high pressure environment of drilling liquid, this paper designs a high reliability bearing assembly by combination of theoretical analysis, numerical calculation and the method of reliability design.According to the operating conditions of bearing assembly, firstly, this paper establishes mechanical models of bearing assembly and analyses the loads applied on it. Transverse forces applied in three conditions are calculated, including the condition that the axis of the bushing is collinear with that of the crown wheel, the condition that the axis of the crown wheel is collinear with that of the BOP and the condition that the pipes contact with the casing. In addition, the rigidity resisting the transverse deformation of the 4(1/8)" packing element is calculated using the method of nonlinear contact finite element method.Then, the main components of the bearing assembly are designed, utilizing the theory of the reliability design and with the aid of FEM. First, the collocation project of bearings is determined by comparisons of different rotating machines. After that, based on the transverse forces calculated, cylinder roller bearings are chosen. Then, the designs of the inner shaft and outer shaft of the bearing assembly are performed, and also, the effects of the deflection of the 3 axes mentioned above on the life of the bearings are analyzed. Finally, the reliability of the whole bearing assembly is calculated.Moreover, in order to endure the high pressure of drilling liquid, a kind of dynamic seal that can be used for contaminant exclusion and lubricant retention in harsh service conditions is chosen. Finally the integrated blueprint is protracted and the first set of bearing assembly of rotating control head is schemed out.