EFFECTS OF NATURAL GAS HYDRATES ON DEEPWATER DRILLING FLUID AND CONTROL MEASURES

With the amount and depth of offshore drilling increased,the offshore drilling operations are getting more and more difficult.The drilling environment is harsh and the operation is complicated.One of the challenges is that the drilling fluid(mainly WBM) is likely to produce natural gas hydrate.Once hydrate is formed in drilling fluid,it will results in unstable wellbore,well plugging,no circulation of drilling fluid,elongated drilling cycle,and increased drilling costs.Herein the mechanism of natural gas hydrates is explained,and it is recommended to fully recognize the potential of hydrates formed at wellheads,BOP,and choke/kill lines before deepwater drilling commences,and to control the well pressure through regulating the drilling fluid density so as to keep the minimum safe drilling fluid to prevent the formation of hydrates.