Surge and Swab Pressure in Oil Drilling

Abstract

Abstract: Surge and swab pressures have been for a while an issue in the drilling of an oil well. The drill string causes a flow for displaced fluid and a pressure change in the borehole when running in or pulling out of the hole. When the string moves upward creates a swab pressure and it creates a surge pressures when moves downward. Surge and swab pressures have for a long time been a problem in the petroleum industry. These pressure changes are mainly related to tripping operations, where the drill string has to be pulled out of the well, normally due to a worn out drill bit, or a broken tool. The desire is to optimize the process and time used to trip in and out of the well, to save time and money, and at the same time not taking any risks. If the tripping speed exceeds a certain limit, the pressure changes in the well may become so severe that the consequences are fatal. The main aim of the thesis is to show the models with the affecting parameters of surge and swab pressures, to explore their effect on the fluid behavior models. The Bingham plastic model, the Power Law model, and the Herschel-Bulkley model are utilized to get the best outcomes. Keywords: surge, swab, pressure, tripping, bottom whole assembly, drilling, oil and gas, well, drilling fluid