Expansion Analysis And Structure Optimization Of Through-Tubing Packer

In recent years,the rapid development of coiled tubing have made great technological progress in through-tubing tools.With the advantages of high efficiency,low risk,economy and time saving,the through-tubing tool can be operated without killing the well or pulling out the completion string,which save a lot of time and minimizes formation damage.These advantages can not be compared with traditional tools.The through-tubing packer is a typical downhole tool in through-tubing operation and has a broad application prospect.However,in the downhole operation of oil and gas wells with complex working conditions,the sealing performance and strength of the through-tubing packer rubber barrel cannot meet the field requirements well.The phenomenon that the steel sheet is "smashed" during the operation of the through-tubing packer often occurs,that is,the laminated steel sheet structure fails and damages,causing the through-tubing cementing operation to fail,seriously affecting the downhole operation efficiency of the drilling site,and leading to drilling costs increase.In order to improve the setting performance of the through-tubing packer during cementing operation and extend its service life in downhole operation,the main work of this paper is as follows:(1)Firstly,the setting mechanism of the tubing packer was studied.According to the sealing requirements of the packer,the key sealing points between the laminated steel sheet and the outer rubber cylinder were analyzed for the vulcanization process,and the single-layer steel sheet and the laminated steel sheet structure were designed and calculated.Finally,the stress state and anchoring force of packer rubber cylinder system after setting are theoretically deduced.(2)Considering the complexity of the simulation of the expansion and setting process of the through-tubing packer,this paper decided to use the ABAQUS simulation method to carry out the numerical simulation analysis.Through the establishment of the finite element model of the through-tubing packer rubber barrel system,the key performance parameters such as the laminated steel sheet stress and the average contact stress of the casing during the setting process were analyzed and the setting performance of the packer was evaluated.Then,on this basis,the influence of internal pressure,single-layer steel sheet structure parameters,laminated steel sheet thickness and rubber cylinder arrangement spacing on the setting performance of the packer were analyzed.(3)Combining the influence of steel sheet structural parameters on the setting performance of the through-tubing packer,the maximum average contact stress(setting stress)on the casing after the packer is set is the objective function,and the numerical simulation test scheme is designed by using the response surface optimization software Design-Expert.The response surface prediction model of the average contact stress of the casing with respect to the length of the steel sheet,the thickness of the steel sheet and the radius of the base circle of the steel sheet was established,and the optimization calculation of the model was carried out to obtain the optimal value under the setting state of the through-tubing packer steel sheet structure parameters.Finally,based on the steel sheet structure parameters,the structure of guard hoop bell mouth was optimized.