The study on erosion of buckling tubing string in HTHP ultra-deep wells considering fluid–solid​ coupling

Abstract

As the first barrier of wellbore integrity, tubing string is an important guarantee for safety production. However, with the rapid consumption of oil and gas, the mechanical environment in wellbore is becoming more and more harsh, which poses a challenge to the safe service of tubing string. In order to systematically study the erosion of buckling tubing string in high temperature and high pressure (HTHP) ultra-deep wells, the researches on buckling deformation and erosion of tubing string are carried out gradually in this paper. There are three steps in the research process: (a) The tests including metallographic, mechanical properties and hardness of studied tubing material are carried out, and the test results are the basis of the next numerical simulation; (b) the finite element model (FEM) of whole section tubing sting-packer-casing is established to study the buckling deformation of tubing string due to the comprehensive effect including piston effect, ballooning effect, temperature effect, friction effect and buckling effect; (c) according to the buckling flow passage, FEM of tubing erosion is established based on erosion mode, fluid–solid coupling and impact of sand on each other. Finally, the erosion rule and failure region on tubing are obtained. The researches presented in this paper can provide reference and guidance for predicting erosion and protecting the tubing string.