Simulation Analysis And Parameter Optimization Study Of Coiled Tubing Injection Head Structure

The coiled tubing operation technology was widely used in many kinds of oil engineering such as oil extraction, well drilling and well logging. As the key component of coiled tubing,the injector head was used to grasp the coild tubing and its reasonable structure greatly enhanced the working life of coiled tubing.During the application of Coiled Tubing Unit,lots of problems appeared in the field,such as the damage of rolling wheel caused by the disability of clamping assembly,the ring sealing failure of wellhead blowout preventer, the coiled tubing's break caused by extrusion, the fracture of injector head chain system, the break of drive shaft and the non-constant down speed of coiled tubing caused by hydraulic system's disordering which had great effects on the construction efficiency of coiled tubing. Therefore, the analysis of the injector head's structure and its parameterization was conducted in this paper, improving the performance and construction efficiency of injector head and enhancing its working life. The main research contents are as follows:The stress states of injector head was analysed and its limit load conditions was confirmed. Then, assuming that the grasping forces were non-uniform distributed, the formula of grasping forces was acquired through the mathematical function formula and elasticity theory, which was proved reasonable by ABAQUS.At the same time,the position of stess concentration was acquired.Therefore,the formula of grasping forces paved the way for the further analysis and optimization of injector head's structure.Through the analysis of effects on the performance of grasping caused by grasping block's shape,the degree of arc angle, the grasping pattern, the friction coefficient and the groove shape, the evaluation method of grasping performance was constructed.then,the reasonable range of effected factor's was acquired,so as to obtain the best shape of grasping block, which was prepared for further optimization of grasping block.The parametric model of grasping block was constructed by ISIGHT optimization software.The relationship between the grasping performance and the groove constructed parameters was achieved by the orthogonal test,which was used to analyse the sensitivity of groove's dimension, and reduce the parameters'range.Based on the above research, the multi-objective optimization of the dimensions of groove grasping block was accomplished, Finally, the optimal dimensions of grasping block with groove were obtained.The dynamics simulation analysis of injector head's chain system was conducted by the software of ADAMS.Then,the variation curve of contact forces between the roller and the sprocket tooth were obtained in the tight side, which the load could be applied to analysis of the static strength of sprocket tooth and roller.At last, the roller and the change rules of contact pressure on the sprocket tooth was obtained. Based on the above research, the analysis of the sensitivity of sprocket tooth's structural parameters were conducted, and the optimal sizes of sprocket tooth's structure were assured by the orthogonal test.The research in this paper provides a new analysis thought and optimization methods to improve the performance of the injector head which had a certain guiding significance to the injector head's structure design.