New Approach for Environmental Load Charts of Jack-ups Considering Actual Preloading Operations

Abstract

The environmental load chart is an important technical support required for the jack-up drilling platform to facilitate its adaptation to different operating waters and ensure the safety of operation. This chart is a crucial part of the platform operation manual. The chart data are closely related to external factors such as water depth, wind, wave, and current conditions of the working water, as well as to the structural characteristics of the platform itself and the number of variable loads. This study examines the platform state under extreme wind, wave, and current conditions during preloading. In addition, this study focuses on the difference between the ultimate reaction force of the pile leg during preloading and the reaction force of the pile leg without considering any environmental load before preloading. Furthermore, the relationship between the difference and the new reaction force of the pile leg caused by the combination of different environmental conditions is established to facilitate the construction of a new form of environmental load chart. The newly formed chart is flexible and simple; thus, it can be used to evaluate the environmental adaptability of the platform in the target well location and provides the preloading target demand or variable load limit according to the given environmental constraints. Moreover, the platform can perform personalized preloading operations, thereby improving its capability to cope with complex geological conditions, such as reducing punch-through risks. This condition reduces the load on jacking system devices and increases its service life.

Keywords

Jack-up / Environmental load chart / Preloading / Geometrically nonlinear effect / Punch through