Service Life of Wellhead Multifunctional Cross in Nitrogen Drilling Process

In order to prevent the multi-function cross accident caused by erosion,the scaled model of multifunctional cross was developed on the basis of similarity theory,then established a set of test device taking the former scaled model as the core.The test results showed that the entrance of bypass of scaled model and entrance to 60 mm distance were suffered serious erosion,while the erosion rate was decline along with time.Adapter bonnet suffered from erosion would affect the service life of multifunctional cross.The adapter bonnet suffered from erosion was evaluated on the basis of the related chapters in standard API 579(2007).The calculation results showed that the multifunction cross would be in danger after the use of 0.26 year.