A new erosion experiment and numerical simulation of wellhead device in nitrogen drilling

• An experiment was conducted on the erosion of a wellhead device used in nitrogen drilling for the first time.
• The simulation results agreed well with data of the erosion experiment.
• Results show that the method is very effective, applicable and helpful to optimize the structure of wellhead device.

During nitrogen drilling in tight sandstone reservoirs, the multifunctional four-way often suffers severe erosion damage after withstanding the erosion of sand and gas over an extended period of time. Such damage may have serious consequences for its functioning. In this study, an experiment was conducted on the erosion of a wellhead device used in nitrogen drilling. The conditions used in the experiment were also used as inputs for numerical simulation of the erosion pattern. The results obtained from the numerical simulation were then compared to those obtained in the experiment in order to determine the reliability of numerical simulation for analysis of erosion pattern in nitrogen drilling. The results of the simulation, scaled down by a factor of 10, were consistent with the results of the experiment. Further, the relative error between the sets of results was less than 5% (the overall mean error is 1.11%) for gas–solid two-phase erosion and flow models implemented using FLUENT software. The results verify that numerical simulation is reliable and can be used to study the erosion of wellhead equipment in nitrogen drilling. This will be of great significance in alleviating the safety problems associated with well control in nitrogen drilling.