BAKER HUGHES - Drilling Fluids Reference Manual

HORIZONTAL AND EXTENDED REACH DRILLING
Settling Barite Particle
Drill Pipe
Annulus
Drill Collars
H.C.*
Bit
0.01 0.1 1 10 100 1,000 10,000 100,000 1,000,000
*H.C = Hydroclones
SHEAR RATE (1/sec)
Figure 11 - 5
Range of Shear Rates in the Fluid Circulation System
700
600
500
Viscosity, cP
400
300
200
100
0
1 10 100 1000
Shear Rate, sec -1
Figure 11 - 6
Effective Viscosity vs Shear Rate
Note that the effective viscosity of the fluid is quite low at bit shear rates, but relatively high in the
annular region for maximum lift. Effective viscosity is the viscosity of the fluid at a specific shear
rate and should be determined for the section of the hole being examined. Calculation and
application of the effective viscosity concept is given in Chapter 1, Fundamentals of Drilling
Fluids, or API Bulletin 13D.
The hole-cleaning concepts of annular velocity and effective viscosity for vertical holes also apply
to high-angle and horizontal wells, but the inclined annulus poses several problems not
encountered in vertical holes.
BAKER HUGHES DRILLING FLUIDS
REFERENCE MANUAL
REVISION 2006. 11-12