INVESTIGATION OF THE EFFECTS OF DRILLSTRING DYNAMICS TO MUD FLOW BEHAVIOUR

The research deals with investigation of the effects of drillstring dynamics to mud flow behaviour. The drillstring motion and mud rheology have significant impact on pressure loss and cutting transport in drillstring. But this has not been explored for an Oil Based Mud (OBM) and other types of mud like Mixed Metal Hydroxide (MMH). The research will explore the pressure loss relationship among inlet velocity, eccentricity and rotational effect along inclination. The viscosity selection is based on Sisko’s model which fits the viscous behaviour fairly for an Oil Based Mud. A part from that, the results of two benchmark cases from Nouar et al. (1998) and Escudier et al. (2002) have been validated by selecting Carbopol 940 (non-Newtonian) as drilling fluid and solved under ANSYS CFX before proceed with an actual case using Bentonite (B128) properties as an Oil Based Mud. Besides regular meshing techniques, Design of Experiment (DOE) is another solving method were used to determine the pressure gradient among inlet velocity, eccentricity and rotational. The input parameters such as inlet velocity, eccentricity and rotation were maintained from and Escudier et al. (2002). The results from DOE method shows that pressure gradient increases with inlet velocity but decreases linearly along pipe radius under eccentric condition and it well illustrated using 2D and 3D Response curve that haven been solved under Latin Hypercube sampling technique