Design and Field Testing of a Nitrogen Circulation Drilling System

Abstract

In the recent decades, the merit of enhancing drilling rate by wellbore gas scavenging has been described comprehensively in many papers. This method began to be used widely and successfully in field conditions. In comparison with air and natural gas, due to its inertness and inflammability, gaseous nitrogen has become the most preferred fluid for drilling. The biggest shortcoming of using nitrogen gas as drilling fluid is high cost of its production. If the nitrogen gas circulated out of the wellbore could be recycled by some ground-based equipment and injected into the wellbore again, nitrogen gas drilling may become more viable. In this work, we developed a new nitrogen gas circulation drilling technology and carried out a systematic study of the proposed project, namely, the technological process, development of separation equipment and control system, etc. To verify the feasibility of this technological system, a comprehensive on-site experiment was designed and implemented for testing the prototype system.