Study On Safety And Countermeasures Of Submarine Pipeline In Shengli Beach Sea

The exploitation of offshore oil is dependent on the transportation of the submarine pipelines,so the safe operation of the submarine pipelines is particularly important.There are lot's of submarine pipelines in the beach area of Shengli Oilfield,and the environmental problems are complex.Studying the structural safety of submarine pipelines in the beach area of Shengli Oilfield under the special environment of landslide,sea ice and storm surge,discussing the protective measures of engineering practice and proposing a preliminary design plan for structural safety preliminary warning can play a guiding role in reducing the safety risk of pipeline operation.This paper has carried out studies on structural safety,and the special environmental of submarine landslide,sea ice,and storm surge facing the submarine pipelines in the Shengli beach area have been considered.The CFD method was used to study the force acting on the submarine pipeline at the massive landslide of landslide initial stage,and combined with the Zakeri massive landslide experiment and simulation analysis validation model,the force at seabed inclination of 0.5 to 5° was calculated and fitted out to get formula,analysis of the effects of landslide bodies on the mechanical properties of buried pipelines and suspended pipelines at different stages,and the safe operating range under the limit state of the submarine landslide was calculated.In view of the exposed risk of the submarine pipeline landing section,the influence of the extreme static ice force on the mechanical properties of the pipeline and the concrete protective layer during the return period from 5 to 100 years and the dynamic response under the steady state dynamic ice force were analyzed.The linear fatigue damage accumulation theory was used to investigate the fatigue damage and life prediction of concrete protection layer of submarine landing pipeline under sea ice.An impact fatigue analysis method for sea ice in landing pipeline was established.The storm surge data was statistically calculated and fitted to obtain the expression of the velocity change of the wave and current caused by storm surge,the safety range of the submarine pipeline under the action of tide was calculated.The safety assessment method for the suspended pipelines under the current was established.In view of the anti-ice of submarine pipelines and the response to landslide and storm surge,common engineering protection measures are discussed.A preliminary design of the safety preliminary warning for submarine pipeline structure of Shengli beach area was made,the system is divided into data input module,management and decision module and feedback module,and a pipeline safety preliminary warning signal acquisition and processing scheme based on UAV remote sensing was proposed as an integral part of the data input module.Through the study of the submarine pipeline structure in a special environment,the following conclusions are drawn.The numerical simulation results of the vertical impact pipe of massive landslide body are compared with the model experiment to verify the accuracy of the model.Different seabed inclinations are used to calculate the force of the massive landslide body on the pipeline and the formula for the force acting on the pipeline containing the angle of the seabed was fitted.The sensitivity of the force is lower when the thickness of the cover soil layer is smaller.A method for calculating the safe range of pipeline structure under the action of the submarine landslide of the limit state was established,which serves as a safety judgment basis for the pipeline structure and provides support for safety preliminary warning.Through the analysis of the mechanical properties of the landing pipeline under the action of sea ice,the concrete protection layer has a significant effect on reducing the sea ice impact on the pipeline.The linear fatigue damage accumulation theory is applied to study the fatigue damage and life prediction of the concrete protection layer of the subsea landing pipeline under sea ice.A method for analyzing the impact fatigue of sea ice on landing pipelines was established,which provided a theoretical basis for engineering practice and had important engineering significance.The storm surge data is statistically calculated and fitted to obtain the expression of the wave and the current velocity caused by the storm surge.The increased value of wave and current can be estimated during the storm surge based on storm surge elevation in engineering.The increase of tidal current at the time of storm surge has a great influence on the mechanical properties of suspended pipelines.The calculation method of the limit suspended length under the action of the tidal current for the suspended pipeline is established,and the safety status of the pipeline is discriminated to provide support for safety preliminary warning method.