Dynamic Simulation On Submarine Cable In Offshore Oil And Gas Exploration

The precise exploration development of marine resources exploration puts forward higher requirements for seismic exploration technology.Submarine cable exploration has advantages of small noise interference,high interpretation accuracy,flexible operation et al.,it has become one of the important topics in the modern ocean development.Whether the submarine cable is placed in the preset position or not,which directly affects the quality of the exploration information.Accurate prediction of cable motion attitude and master the cable kinetics is the keys to control the motion of submarine cable.The present thesis mainly concerns the modeling of submarine cable system,numerical method as the researching means,based on the former related research,is employed to study the steady-state and dynamic motion of submarine cable.The research of this thesis may help to forecast the response and movement of submarine cable system accurately,and provide theoretical support for the design and application of submarine cable system.The main contents and conclusions of this thesis can be summarized as follows:1.The research methods and influencing factors of submarine cable system are summarized,and the existing problems are analyzed.2.The three-dimensional submarine cable steady-state model is established using the infinitesimal method,with the consideration of the ocean currents,combined with initial boundary value,finally solved by fourth order Runge Kutta method.3.From the expansion point of view,a three-dimensional submarine cable dynamic motion model is established using the lumped mass method,the effect of non-uniform current,changes in the speed of ship,node with a certain interval distribution are taken into consideration,solved by fourth order Runge Kutta integration method.The node-cable coupling model is established;The cable laying simulation is realized,and the simulation process is given.4.The effect of initial value,marine environment,cable's physical coefficients are thoroughly studied when the system is in steady-state,which include initial tension setting,initial angle setting,the wet weight of cable,drag coefficient,current velocity,cable laying speed et al.These results indicate that: The effect of initial tension and initial angle on the steady cable Euler angle is very small,which has great effect on the cable motion attitude and the cable tension;The effect of the variation of normal resistance coefficient and initial angle on the cable tension is very small,and it can be neglected;In addition to the drag coefficient,the above mentioned factors all have effect on the steady-state motion of the cable.5.Based on the dynamic simulation of submarine cable laying process,the motion characteristics of submarine cables under different dynamic response are analyzed: When the ship speed increases,the cable tension will increase,the bottom slack will decreases;When the cable laying speed increases,the cable tension will decrease,the bottom slack will be accompanied with increase,and the lateral offset and longitudinal offset of the sink points subsequently will decrease;The smaller the impact of the ocean current with depth on the cable closer to the bottom of the sea;The effect of the change of the node layout length on the cable motion attitude is small;Regardless of the type of the node,the tension and the sinking speed of the cable with nodes are greater than the tension and the sinking speed of the cable without nodes.