Numerical Simulation of Pressure Loss in Largesize Annulus of Deepwater Drilling Riser

Abstract

Large difference exists between largesize annular hydraulics and conventional well's. Using numerical simulation, this article analyze annular pressure loss of deepwater drilling riser with large size, describing how various parameters such as annular mud velocity, drill pipe rotation speed, mud property and annular clearance affect the pressure losses in a well, compared with that of a conventional wellbore as well. Theoretical calculations have shown: As for power law fluid in the largesize annular space, when it comes to laminar flow, an increase in drill pipe rotation speed can result in a decrease of annular pressure losses; In the contrary,under turbulent conditions, this may lead to a rise in annular pressure losses. The pressure drop dramatically along with an increasing in the annular space, in other words, the size of annular clearance is a major factor that affect the pressure losses in the annular space.