Chapter 7.2 Lifting Capacity of Drilling Fluids
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Internal 1
1InternalPCB – 4223 DRILLING HYDRAULICS SEMESTER- JANUARY 2015
BY . ASIF ZAMIR
UNIVERSITI TEKNOLOGI PETRONAS
PETROLEUM ENGINEERING DEPARTMENT
Chapter 7.2
• Fluid Velocity in Annulus
• Particle Slip Velocity
• Particle Reynolds Number
• Friction Coefficient
• Example
• Iterative Solution Method
• Alternative Solution Method
• API RP 13D Method
2InternalPCB – 4223 DRILLING HYDRAULICS SEMESTER- JANUARY 2015
BY . ASIF ZAMIR
UNIVERSITI TEKNOLOGI PETRONAS
PETROLEUM ENGINEERING DEPARTMENT
Internal 2
Historically, when an operator felt that the hole was not being cleared of cuttings at a satisfactory rate, he would:
Increase the circulation rate
Thicken the mud(increase YP/PV)
3InternalPCB – 4223 DRILLING HYDRAULICS SEMESTER- JANUARY 2015
BY . ASIF ZAMIR
UNIVERSITI TEKNOLOGI PETRONAS
PETROLEUM ENGINEERING DEPARTMENT
More recent analysis shows that:
Turbulent flow cleans the hole better.
Pipe rotation aids cuttings removal.
With water as drilling fluid, annular velocities of 100-125 ft./min are generally adequate (vertical wells)
4InternalPCB – 4223 DRILLING HYDRAULICS SEMESTER- JANUARY 2015
BY . ASIF ZAMIR
UNIVERSITI TEKNOLOGI PETRONAS
PETROLEUM ENGINEERING DEPARTMENT
Internal 3
5
A relatively “flat” velocity profile is
better than a highly pointed one.
Mud properties can be modified to
obtain a flatter profile in laminar flow
e.g., decrease n
InternalPCB – 4223 DRILLING HYDRAULICS SEMESTER- JANUARY 2015
BY . ASIF ZAMIR
UNIVERSITI TEKNOLOGI PETRONAS
PETROLEUM ENGINEERING DEPARTMENT
Drilled cuttings typically have a density of about 21 lb/gal.
Since the fluid density is less than 21 lb/gal the cuttings will tend to settle, or ‘slip’ relative to the drilling mud.
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s lipf luidpart ic le VVV
Density & Velocity
slipV
partic leVf luid
_
V
InternalPCB – 4223 DRILLING HYDRAULICS SEMESTER- JANUARY 2015
BY . ASIF ZAMIR
UNIVERSITI TEKNOLOGI PETRONAS
PETROLEUM ENGINEERING DEPARTMENT
Internal 4
Velocity Profile
The slip velocity can be reduced by modifying the mud properties such that the velocity profile is flattened:
Increase the ratio (YP/PV)(yield point/plastic viscosity) or
Decrease the value of n
7InternalPCB – 4223 DRILLING HYDRAULICS SEMESTER- JANUARY 2015
BY . ASIF ZAMIR
UNIVERSITI TEKNOLOGI PETRONAS
PETROLEUM ENGINEERING DEPARTMENT
Plug Flow
Plug Flow is good for hole cleaning. Plug flow refers to a “completely” flat velocity profile.
The shear rate is zero where the velocity profile is flat.
8InternalPCB – 4223 DRILLING HYDRAULICS SEMESTER- JANUARY 2015
BY . ASIF ZAMIR
UNIVERSITI TEKNOLOGI PETRONAS
PETROLEUM ENGINEERING DEPARTMENT
Internal 5
Newtonian Fluids:
The terminal velocity of a small spherical particle settling (slipping) through a Newtonian fluid under Laminar flow conditions is given by STOKE’S LAW:
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2
sfss
d)(138v
InternalPCB – 4223 DRILLING HYDRAULICS SEMESTER- JANUARY 2015
BY . ASIF ZAMIR
UNIVERSITI TEKNOLOGI PETRONAS
PETROLEUM ENGINEERING DEPARTMENT
Where
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cp viscosity, fluid
in particle, of diameterd
lbm/gal fluid, of density
lbm/gal particle, solid of density
ft/s velocity, slipv
s
f
s
s
2
sfss
d)(138v
InternalPCB – 4223 DRILLING HYDRAULICS SEMESTER- JANUARY 2015
BY . ASIF ZAMIR
UNIVERSITI TEKNOLOGI PETRONAS
PETROLEUM ENGINEERING DEPARTMENT
Internal 6
Stokes’ Law gives acceptable accuracy for a particleReynolds number < 0.1
For Nre > 0.1 an empirical friction factor
may be used.
11
ssf
Re
dv928N
InternalPCB – 4223 DRILLING HYDRAULICS SEMESTER- JANUARY 2015
BY . ASIF ZAMIR
UNIVERSITI TEKNOLOGI PETRONAS
PETROLEUM ENGINEERING DEPARTMENT
12
What forces act on a settling particle?
Non-spherical particles
experience relatively higher drag
forces
InternalPCB – 4223 DRILLING HYDRAULICS SEMESTER- JANUARY 2015
BY . ASIF ZAMIR
UNIVERSITI TEKNOLOGI PETRONAS
PETROLEUM ENGINEERING DEPARTMENT
Internal 7
13
Sphericities for Various Particle Shapes
Shape Sphericity
0.58 20rh
0.87 2rh
0.83 rh
0.59 r/3h
0.25 r/15h
Cylinders
0.73 3*2*
0.77 2**
Prism
0.81 Cube
0.85 Octahedron
1.00 Sphere
InternalPCB – 4223 DRILLING HYDRAULICS SEMESTER- JANUARY 2015
BY . ASIF ZAMIR
UNIVERSITI TEKNOLOGI PETRONAS
PETROLEUM ENGINEERING DEPARTMENT
14InternalPCB – 4223 DRILLING HYDRAULICS SEMESTER- JANUARY 2015
BY . ASIF ZAMIR
UNIVERSITI TEKNOLOGI PETRONAS
PETROLEUM ENGINEERING DEPARTMENT
Internal 8
Particle Reynolds Number
In field units,
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189.1
f
sss
f
dv
Based on real cuttings
InternalPCB – 4223 DRILLING HYDRAULICS SEMESTER- JANUARY 2015
BY . ASIF ZAMIR
UNIVERSITI TEKNOLOGI PETRONAS
PETROLEUM ENGINEERING DEPARTMENT
1. Calculate the flow velocity.
2. Determine the fluid n and K values.
3. Calculate the appropriate viscosity (apparent viscosity).
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4. Calculate the corresponding Particle Reynolds
number.
InternalPCB – 4223 DRILLING HYDRAULICS SEMESTER- JANUARY 2015
BY . ASIF ZAMIR
UNIVERSITI TEKNOLOGI PETRONAS
PETROLEUM ENGINEERING DEPARTMENT
Slip Velocity Calculation (using Moore’s Correlation)
Internal 9
17InternalPCB – 4223 DRILLING HYDRAULICS SEMESTER- JANUARY 2015
BY . ASIF ZAMIR
UNIVERSITI TEKNOLOGI PETRONAS
PETROLEUM ENGINEERING DEPARTMENT
Slip Velocity Calculation (using Moore’s graph)
18InternalPCB – 4223 DRILLING HYDRAULICS SEMESTER- JANUARY 2015
BY . ASIF ZAMIR
UNIVERSITI TEKNOLOGI PETRONAS
PETROLEUM ENGINEERING DEPARTMENT
Internal 10
19InternalPCB – 4223 DRILLING HYDRAULICS SEMESTER- JANUARY 2015
BY . ASIF ZAMIR
UNIVERSITI TEKNOLOGI PETRONAS
PETROLEUM ENGINEERING DEPARTMENT
Reference
Chapter 4, Applied Drilling Engineering by
Chapter 5, Drilling Engineering by J.J. Azar and
G. Robello Samuel.
20InternalPCB – 4223 DRILLING HYDRAULICS SEMESTER- JANUARY 2015
BY . ASIF ZAMIR
UNIVERSITI TEKNOLOGI PETRONAS
PETROLEUM ENGINEERING DEPARTMENT
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