Dynamic Load Characteristic Researeh Of Dual Derrick On Deep Water Rig

In recent years, with the growth of China’s oil demand and the decline of oil production in the main land, people began to divert attention from land to the ocean. Deep-sea drilling ship is a large offshore floating structure for offshore oil development, which has superior athletic performance and widely be used in deepwater operations far from the sea. Dual derrick is important rig equipment in hoist system on the ship, whose work environment is more complicated than the land derrick’s work environment. Therefore dual derrick bears not only the conventional working load but also the wind load, the vibration load as well as the wave load. For this reason, in order to ensure the quality of drilling, researching on reliability and dynamic load characteristics of dual derrick on deep water drilling ship has important significance.Through the survey of dual derrick, get the drilling process and feature. Analyze the main form equipped in the semi-submerged platform and drilling ship, finish the initial setting of parameters. According to API SPE4F, calculate and distribute loads (dead loads, operating load, wind load and dynamic load). Then set the compound mode of dual derrick loads according to the criterion.Build the finite element model of dual derrick by ANSYS, obtain the stress distribution and the deformation tendency under the static load, which may provide reference for evaluating dual derrick. Finish the linear and nonlinear bucking analysis to obtain critical load, the result shows dual derrick will not lost stability.Introduce the basic conception of reliability and structural system, provide the computing method of the whole reliability of dual derrick. According to the calculating results of finite element static strength, iterative calculate the reliability of dual derrick and compare with the general standard, it turns out that dual derrick is safe and reliable.Finishe the dynamic characteristics of dual derrick including modal analysis and harmonic response analysis, then obtain first ten natural frequencies and corresponding modes as well as the transformation law of structure response along frequencies.