The Risk Pre-warning Research Of Towing Cylindrical Drilling Platform

The National Energy Development Strategy from 2014 to 2020 calls for strengthening exploration and development of offshore oil and gas to vigorously promote their production,therefore the number of offshore drilling platform will increase.The cylindrical drilling platform has been favored by more and more countries around the world owing to its advantage of advanced technology,security,stability and operational reliability.The cylindrical drilling platform towing process is the precondition to put it into use,which is saturated with risk for the complexity of towing environment,towing maneuvering and towing program,and the sudden and severity of accident.Consequently,how to guarantee the safety of towing and improve the effect of risk prediction are increasingly becoming the focus problems of the engineering and technical person and researchers,particularly the relevant water traffic management departments.In this paper,firstly,on the basis of the MMG model,the motion model of the towing system is constructed combining the catenary model.Secondly,the real-time trajectory prediction model is constructed based on the Kalman filtering algorithm to realize the real-time tracking and prediction of the trajectory of the towing system.Finally,the risk pre-warning system of the towing system is constructed according to the pre-warning index criteria to made real-time pre-warning,and the pre-warning contents contain high-probability risks of the towing system,such as the collision,grounding,yawing and etc.This system can not only identify the potential risks and raise the alarm,but also provide corresponding measures combining relevant collision-avoidance regulations and the practical navigation environment in the water area to mitigate and eliminate the risk.Therefore,researching the risk pre-warning of the towing process of the large-scale cylindrical platform has important significance to the security of the towing system.To sum up,the main contents and results in this paper are as follows:(1)Constructing the motion model of the towing systemThe motion model of the towing system is constructed based on the MMG theories and the catenary model,and several groups of simulation experiments under different experimental conditions are designed to verify the availability of the motion model of the towing system.The experimental results show that the larger the scale of the external operation,the more difficult it will be for the tug and the cylindrical drilling platform to recover the stability and the more obvious the fluctuation of their trajectories will be.Therefore,in the practical towing operation process,large-scale motivated operation should be avoided to reduce the probability of serious incidents caused by the out-of-control of the towing system.(2)Constructing the real-time trajectory predication model of the towing systemBased on the Kalman filtering algorithm,the real-time trajectory prediction model of the towing system is constructed to realize the real-time tracking and prediction of the ship motion trajectory,and simulation experiments under different experimental conditions are designed to verify its feasibility.The error analysis of the trajectory prediction showed that with longer predicting time-step,higher towing speed and larger scale of operation,the error of the trajectory prediction will be larger.In addition,reasonable prediction time should be determined combining the actual condition of the environment and traffic flow to increase the trajectory prediction accuracy on the condition that the engineering practicability of model is guaranteed.Based on the results of the prediction error analysis in the experiments,and combining the practical pre-warning demand,the pre-warning time-step is set as 10 s,which can provide theoretical basis for the future research of the risk pre-warning of the towing system.(3)Constructing the risk pre-warning model of the towing systemThe risk pre-warning system of the towing system is constructed on the basis of the pre-warning index criteria,and high-probability accidents(including collision,grounding and yawing)are involved in the range of pre-warning,and the pre-warning index of each type of accident is determined.Then combining the practical condition of the towing process,the corresponding pre-warning condition,pre-warning methods and process are determined,and measures of the mitigation and elimination of the risk are proposed combining relevant collision-avoidance regulations and the actual navigation surrounding.In addition,to verify the availability and practicability of the risk pre-warning model of the towing system,the simulation experiments are designed based on the trajectory predicating results of the tug and the cylindrical platform in the towing system.