METHOD FOR DRILLING THROUGH NUISANCE HYDROCARBON BEARING FORMATIONS

摘要

A method for controlling entry of hydrocarbon into a wellbore from a subsurface formation includes determining whether hydrocarbon is entering the wellbore. Whether a rate of hydrocarbon entry into the wellbore is slowing is then determined Control of discharge from the wellbore is then switched from maintaining a selected wellbore pressure to controlling a rate of discharge of fluid from the wellbore to be substantially constant if the hydrocarbon entry rate is slowing. Control of discharge from the wellbore is returned to maintaining the selected wellbore pressure when the hydrocarbon stops entering the wellbore.