Wellhead and conductor fatigue loading is becoming an increasingly important issue in offshore drilling operations. A move towards higher pressure and higher temperature wells, deeper water and increasingly inhospitable environments has led to a substantial increase in the weight and size of offshore equipment. This, combined with dynamic loading from the environmental forces acting on the vessel and riser, has greatly increased the loads that subsea wells are exposed to. Over the past few years, this has increased the potential for severe fatigue loading in the wellhead and conductor system. This paper highlights the major factors driving fatigue loading in the wellhead and conductor system, including environmental factors as well as those resulting from the use of larger 5th and 6th generation rigs for offshore drilling activities. Particular focus is given to the growing use of structural monitoring in order to more accurately assess loading in the wellhead and conductor system and thus reduce the inherent conservatism present in fatigue analysis. By allowing the calculation of actual fatigue damage throughout a drilling campaign, monitoring can provide critical data for ensuring the structural integrity of the wellhead system.
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