double stage casing head
In addition to all the features of single-stage casing head ，the double-stage casing head presents the following features: Through putting the testing plug into 9-5/8 "hanger before pressure test of the third section drilling, Can be fully detected quality of the second section drilling. The procedures and workforce of installing BOP can be shorten through Optimizing design of the casing head and the wellhead equipment can be installed at one time. The protection sleeve of the third section drilling don’t have to be removed due to the optimum design of structure.
