Study On Mooring Assisted Dynamic Positioning Controlling Of Semi Submersible Drilling Platform

With the exploitation of of fshore oil and ga s gradually moving towards the deep sea, people are more and more atten tion to the res earch on the positioning of the large scale equipment in deep sea oil and gas exploitation. Semi-submersible drilling platform, as an important equipment of deep-water oil and gas exploitation, is very important for its safe, reliable and econom ical positioning. Moorin g positioning is lim ited by water depth, increasing the cost and the dif ficulty of an choring, and the positioni ng is not accurate; Dynamic positioning is not affected by water depth, but the huge fuel co nsumption greatly increases the cost. Mooring assisted dynam ic positioning com bined the advantages of mooring positioning and dynamic positioning, it can not only position accurately, but also can reduce the fuel consumption and the cost. This paper takes the semi-submersible drilling platform as the res earch object, and studies on the m ooring assisted dynamic positioning system, the main work is completed as follows:The low frequency m otion model of the plat form, the mathem atical model of the external environment disturbance force and the mathematical model of hydrodynamic force are established in this paper in order to study m ooring assisted dynamic positioning system more conveniently.In order to study on the mooring system, this paper takes static analysis and dynam ic analysis of the m ooring system respectively by using catenary theory and finite elem ent theory. At the sam e time, the ti me domain coupled calculation process of the mooring system is studied and the dom ain motion in surge, sway and ya w direction of the platfor m is simulated through the simulation experiments.This paper selects the im proved Sage-Husa adaptive filter due to the r elatively high model requirements of Kalman filtering. Some simulation experiments are taken to compare the filtering effect of the two f ilters. Genetic algorithm is in troduced to the ro lling optimization processes of the generalized predictive control to improve the searching speed and precision. Then some simulation experiments are taken to compare the control effect of GPC controller and GA-GPC controller.This paper designs the cont rol system of the mooring assisted dynamic positioning system based on GA- GPC controller and dynam ic cable tension controller, and the simulation experiments are taken to verify the effectiveness of the control system. Finally, the time-domain motion sim ulation process o f the platform is provided, and m ovements situation of the platform in the sur ge, sway and yaw direction is sim ulated, the simulation results indicate the availability of the mooring assisted dynamic control system.