Analysis Of Dual Derrick Structure

Oil and gas exploitation of deepwater has become a trend of offshore drilling. Because of the characteristic of deepwater drilling, at the end of the twentieth century maritime drilling engineer proposed the dual derrick drilling technology. The main idea is two drilling modules are outfitted in the derrick. It can parallel drill, reduce the key drilling process and improve efficiency. Derrick is one of the most important equipment in hoist system. The derrick can lay equipment and is the back-up unit. Therefore, the research of derrick structure is necessary.Through the survey of dual derrick, analyze the drilling process and characteristic. List the semi-submerged platform and drill-ship that equipped dual derrick, also the main form of dual derrick. Select the proper topology structure and finish initial setting of parameters. In view of the characteristic of dual derrick, define the load of derrick. Such as dead load, operating load, wind load and dynamic load. Then set the compound mode of derrick loads according to the criterion.Introduce the structure design theory and optimization design module of ANSYS. Build the finite element model of derrick. Use method different from the traditional design, set design variables, state variables and objective function, and then use optimization design module to calculate in different working condition, and finally determine the optimum result.Study the mechanical behavior of dual derrick. Do static analysis of derrick using finite software, and find the stress distribution and the main bearing carrier. Do modal analysis, and find natural frequencies and modes of vibration of dual derrick. Do harmonic response analysis, and ascertain the response of the stability with load changes over time and the rule of that structure in response to changes in the frequency. Do stability analysis, and find the critical load.