Surge and swab during drill pipe connections on floaters may affect pressure windows in calm weather

摘要

DURING DRILLING AND COMPLE-tion, the downhole pressure in a well should be kept lower than the fracture pressure and higher than both the pore pressure and wellbore collapse pressure. Falling below that lower limit pressure could lead to wellbore stability challenges and a possible undesired influx of hydrocarbons into the well, while exceeding the upper limit could cause the well to fracture, resulting in costly mud losses. All of this means an increase in nonproductive time (NPT) and higher drilling costs.