Abstract: Deep-water formations with a narrow pressure window pose a huge challenge to casing running. The surge-swab pressure generated during casing running will cause the wellbore pressure to exceed the upper limit of the formation pressure window and cause lost circulation. When a lost circulation occurs in offshore operation, the operating time will be greatly increased. In order to prevent excessive surge-swab pressure from exceeding the safety pressure window when using conventional methods for casing running, the casing running speed can be reduced. This reduces the leakage risk to a certain extent, it increases drilling costs, but does not apply to some wells. Therefore, for leakage risk during casing running in deep-water narrow safety pressure window formations, a deep-water narrow safety pressure window wellbore pressure control model is established on the basis of dynamic surge-swab pressure; and a deep-water precise-control managed pressure method for casing running is proposed. Using the established dynamic surge-swab pressure model to analyze the influencing factors of wellbore pressure, it is found that the surge-swab pressure of the wellbore increases with the increase of casing depth, maximum running speed, drilling fluid density, yield value and viscosity of drilling fluid. The calculation results show that shows that the precise managed pressure in deep water not only reduces the leakage risk, but also shortens the operation time and reduces the operation cost.

Key words: deep-water, precise managed pressure, casing running, surge-swab pressure, lost circulation