Study About Deformation Of Submarine Manifold Under The Impact By Falling Objects And Dynamic Response In The Wave And Current Action

As an important way to develop oil and gas fields,submarine manifold has been widely studied and applied in most countries of the world.During the installation and service,submarine manifold are in a very complex marine environment,it may be subject to the impact of falling objects and affected by wind,wave and current loads,etc.at any time.Once submarine manifold failures,not only will affect oil and gas production activities,causing huge economic losses,the leaked fluid will pollute the marine environment,and even lead to ecological disaster.Therefore,it is necessary to study the collision and dynamic response of manifold.First,according to the probability calculation model of crane falling objects introduced by DNV-RP-F107,established the probability calculation model of submarine manifold.In an anchored accident,proposed a numerical methods of submarine manifold's anchor hit probability.And the parameters discussed,analysis proved the reliability of the mathematical model.Secondly,the collision damage of a submarine manifold impacted by anchor job is simulated,mainly studies the stress and deformation.Through a large number of numerical simulation obtains: in the same impact energy,the smaller the contact area between the anchor and the submarine manifold,the smaller the damage area of submarine manifold,the greater the depth of damage and in a small impact energy,stress can reach the yield strength,so more prone to plastic deformation.When the contact surfaces of anchor and manifold is the same,The greater the impact energy,the more serious damage deformation.When the impact energy is small,shear elastic modulus of seabed increases,manifold's dent depths and the maximum equivalent stress essentially unchanged,but,when the impact energy is large,with the seabed's shear elastic modulus increasing,manifold's dent depths and the maximum equivalent stress increase.But with the increasing of seabed's cohesion and internal friction angle,manifold dent depth and maximum stress value basically unchanged.Finally,Submarine manifold's model is established,submarine manifold's dynamic response are calculated,and analyze the influence of different factors on the dynamic response of the submarine manifold.Under the wave and current action,manifold's movement in X,Y direction is irregular cyclical movement.Wave height increases,manifold's movement frequency increases,displacement amplitude in the X,Y direction also increases.Wave period increases,manifold's displacement amplitude in X,Y direction tends to decrease.Greater depth in the water,manifold's displacement amplitude in X,Y direction is significantly smaller,and manifold movement frequency is significantly reduced.