Wellhead stability analysis of surface casing running for deepwater drilling

By virtue of the jetting based surface conductor setting technology, the surface conductor can be set in the process of jetting, so the difficulty that the wellhead cannot be found easily when the surface conductor is lowered after the deepwater surface drilling is solved and the drilling of two sections is completed in one trip of string operation.As for deepwater drilling operations, however, when the surface conductor is lowered, there is a large offset between the platform and the surface casing with the increase of the lowering depth due to the influence of wind and waves, which brings about a great risk to the operation.A conductor strength check and underwater wellhead stability analysis model for the jetting based surface casing setting of deepwater drilling was established based on the Ansys finite element analysis software.Then, it was applied to check the equivalent stress of the first surface casing at the underwater wellhead with no inclination and different inclination angles.And accordingly, the maximum offset of the platform based on the prerequisite of safe operation was obtained.The research results could be used as the guidance for actual engineering.