Effect Evaluation And Structure Optimization Of Coiled Tubing Shear Ram Blowout Preventer

In case of a safety accident,shear ram blowout preventer(shear ram BOP)is to shear and seal the string in the well.And coiled tubing has the advantages of low cost and high efficiency,which is widely used in drilling,completion,oil and gas development and other operations.Therefore,combining theory,simulation and test,this paper studied the shear performance of the coiled tubing shear ram BOP,and analyzed its influencing factors to improve the shear efficiency and shear effect.After analyzing the shear deformation and mechanical behavior of coiled tubing,the common material models are described and compared.Combining the material characteristics of coiled tubing,it is finally determined that elastic-plastic constitutive model and damage initiation criterion,and then the damage evolution of metal material is expounded.The selected model and parameters are imported in the finite element software,and then carry out the simulation of the shear process,combining with the working conditions of the coiled tubing shear process.The simulation results of coiled tubing and shear ram are analyzed.At the same time,it is explained the change of coiled tubing fracture section and the shear force changing of shear ram.Shearing process and effect can be reflected by geometrical morphology of coiled tubing fracture cross section.After analyzing the deformation process of coiled tubing,based on the theory of metal plastic deformation and combined shear ram structure,it is assumed that the deformation process of coiled tubing is an eight plastic hinge structure,so the fracture morphology model is established,and then calculate the example.The shear test is designed,and the modal results,simulation results and test results are compared,the differences meet the error requirement.The finite element method is used to analyze the influencing factors in the shearing process,such as the shear ram structure parameters:shear blade thickness,V-angle,chamfer;and the important parameters of coiled tubing:wall thickness,outer diameter.When it is remain unchanged that the basic structure of the shear ram and the stress position of the coiled tubing,the factors are optimized and improved affecting the shear process to further raise the shear efficiency and reduce the stress,so as to provide a reference for the design of the coiled tubing shear ram BOP.