Using the principle of fluid mechanics and the geometnc properties of the annuli in directional wells, the law of laminar helical flow of drilling fluid in eccentric annuli was studied. Analytical solutions of apparent viscosity, velocities, flow rate, pressure drop and the stability parameter are presented. Results of numeral simulations are given. Laboratory smdies and field application in eleven wells of Daqing oil field were used to validate the theory. A method for calculating pressure drop in annuli, which can be used in designing hydraulic parameters of directional wells is given.

Keywords:
Upstream Oil & Gas, application, Directional Drilling, directional well, drilling fluids and materials, helical flow, drilling operation
Subjects:
Directional drilling, Drilling Fluids and Materials, Drilling Operations
Copyright 1997, Society of Petroleum Engineers
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