Virtual Testing of the Performance of Sealing Elements in Wellhead Isolation Tools (Paper No. 81)

摘要

The Wellhead Isolation Tool (WIT) isolates the wellhead from exposure to treating fluids and pressures. The WIT contains a seal element (cup) and mandrel that are inserted through the existing treebore and tubing hanger into the production tubing. The sealing element is energized by differential pressure to provide a seal between the mandrel OD and tubing ID. The performance of the sealing element, WIT cup, subject to a large variation of tubing ID, is of great interest. The technical challenges are 1) whether a cup can be set properly in the maximum ID; 2) once set, what maximum pressure the cup can sustain. Virtual testing (nonlinear FEA simulation) on WIT cups for determination of operating pressure envelope can significantly reduce the time and money spent on testing and help designers better understand cup operating and failure mechanics. In this paper, the work on the first stage of the virtual testing, which is for validation purposes, is presented. During the study, improvements on mathematical description of rubber compression behavior and rubber failure criteria are made. Virtual tests on two types of WIT cup, in two casing sizes are successfully conducted, and virtual test results are validated by lab tests afterwards.