The Study On Performance Of Wet Insulation Pipe In Deep-sea

As onshore oilfield is drying up,petroleum development is gradually shifting to marine areas,especially to deep sea areas.Pipelines in deep sea-an important part of petroleum development-are responsible for transporting oil and gas to shore.The deep-sea environment-high pressure and low temperature-often brings temperature drop and compression deformation to pipelines during service.It should be took seriously,otherwise pipelines may be plugged or pressure-fed.Performance of Wet Insulation Pipe in Deep-sea need be studied to ensure the safe operation of pipeline.First,this paper designs the experimental device to study the performance of Wet Insulation Pipe in Deep-sea,from requirements and purpose of the experiment.The design includes high pressure tank,test pipe and other auxiliary systems.And it solves three key technical problems,such as the strength of high pressure tank,the end effect and the accuracy of the measurement and control.Reference to national and industry standards,thickness of the cylinder,spherical head and flat cover are calculated.Then,stress and deformation of the high pressure tank are analyzed by the finite element knowledge to ensure the using security.Extreme operating condition is simulated by FLUENT software to determine the minimum length of test pipe.This design use multiple-point measurement and control technology to ensure the accuracy.Then,this paper studies heat transfer performance of the wet insulation pipe in deep-sea,through theoretical analysis,experiment and numerical simulation.Thermal contact resistance,heat resistance and heat transfer coefficient of the wet insulation pipe are analyzed by theory.And the change with temperature is discussed by experiment.Base on this,the heat transfer model is build,though analyzing the thermal influence and hypothesis(heat conductivity coefficient,convective heat transfer coefficient and thermal contact resistance,etc).After determining the relevant physical parameters,heat transfer of the wet insulation pipe under normal operation and shutdown process is simulated to study the heat dissipation and safe shutdown time,and analyze many factors including water temperature,water flow velocity,insulation layer thickness,thermal conductivity and size of the pipe.Finally,this paper analyzes compressive creep performance of the wet insulation pipe in deep-sea.The creep theory and model of polyurethane is discussed.And radial deformation of the wet insulation pipe under hydrostatic pressure is calculated.Though the creep tests of polyurethane,the influence of stress and temperature on creep behavior of polyurethane is studied.And the creep constitutive equation is built.On the base of stable temperature field,which is calculated in the previous part,the compressive creep performance of the wet insulation pipe in deep-sea is analyzed by ANSYS software.The influence of the depth of the pipeline,transmission temperature and the thickness of thermal insulation layer on creep behavior is discussed.