Coiled Tubing Injector Head Skid And Roller Damage Study

The coiled tubing injector head is widely used in oilfield development operations due to its intelligence,high efficiency and safety.As an important part of the head,the skids and rollers provide continuous pipe clamping force and ensure the normal lifting and lowering of the pipe,which plays a key role in the safe operation of the head.The internal damage to the skid plate and roller is used as the object of the study.The causes of damage to the skid plate and roller are analysed through experimental methods,and the working and structural factors affecting the contact performance of the skid plate and roller are analysed from a mechanical point of view through finite element methods.This study is of great practical importance and the main research elements are as follows:Firstly,the damage to the skid plate and roller was characterised and analysed by means of experimental methods,and material performance testing was completed.The damage to the skid plate and roller was concluded to be caused by biased loading and slipping of the roller when rolling on the surface of the skid plate,resulting in excessive stress on the end of the roller and the surface of the skid plate,brittle breaking of the roller and plastic deformation of the surface of the skid plate.Secondly,through the finite element method,the creep-slip characteristics of the skateboard-roller were studied,and the influence of the friction coefficient,clamping load and rolling speed on the creep-slip rate was analysed,and it was concluded that the friction coefficient between the skateboard and the roller was set in the range of 0.08-0.09,the rolling speed of the roller was kept at 12m/min and the clamping load was set at 64 k N,which helped to reduce the creep-slip rate of the roller.Once again,through the establishment of the contact mechanical model of the skateboard-roller contact behaviour was studied,the impact of clamping load,surface hardness and friction coefficient on the contact performance was analysed,and it was concluded that when the skateboard-roller rolling contact,the maximum contact stress is located at the end of the roller,and the maximum Mises stress and shear stress are located in the outer sub-surface part of the contact area of the skateboard,which is prone to cracking and damage.Increasing the surface hardness of the skid plate to 60 HRC and maintaining the friction coefficient in the range of 0.08-0.09 will help to reduce the damage to the skid plate and the roller.Finally,a force analysis of the skid plate-roller slip contact state was carried out,combined with the finite element method to derive the load-deformation equation applicable to the slip contact.By establishing the mechanical model of skid plate and roller offset load contact,the influence of offset load and skidding on the contact performance is analysed,and it is concluded that offset load and skidding will lead to a sharp increase in contact stress,with the maximum stress located at the end of the roller and the sub-surface part of the skid plate,which is very likely to cause brittle breakage of the roller and plastic deformation of the skid plate surface.Avoiding deflection and slippage of the rollers can effectively reduce damage to the skid plate and rollers.The above study identifies the causes of damage to the skids and rollers,which provides a scientific basis for the design of the skid-roller contact system and is of some significance for improving the safe operation of the injector head.