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Screens for Frac Packing
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Screens for Frac Packing
• Screen types
• Screen characteristics that lead to failures
• Production and reservoir characteristics that
affect screen selection
Prepacked Screen – minimum thickness prepack
Prepacked liner with center screen – very durable but
plugs easily with fines.
A few things that cause screens
to fail……… • Running screens
– drag, sharp turns, windows, dope, shale,
• Pumping past screens
– erosion, pressure, screenouts
• Pumping through screens
– Fines in packing fluid, rate, volume
• Producing through screens
– Fines in drill-in fluid, mobile fines, pressure drop
• Compaction loads
Liquid
return to
surface
slurry Failure points in the flow path during frac
or gravel packing:
1. Crossover port
2. Casing opposite
crossover port.
3. The annular area between screen and
casing wall.
a. Erosion from high velocity linear flow
– minimal problem
b. Erosion from high velocity flow as
the slurry enters a perforation.
c. Pressure drop in this area during high
rate flow (fracs) can collapse screens
– problems are very rare, but watch
clearances.
Hole
Size
Vol of
solids in
the filter
cake
Wt of
solids
Size of
solids
cu. in./ft. lb/ft microns
4.5" 4.9 0.48 5 to 1000
6.125" 6.6 0.65 5 to 1000
Solid Debris in the Completion Interval from a
“Clean” Drill-In Fluid
Screen
Opening
Screen
Diam
Opening area
per linear ft of
screen
% of wall area
open to flow in a
wire wrap screen
0.008" 4 10.9 7%
Screen Opening – with and without prepack
% open in a
prepack
screen?
Maybe 1%, or
less?
Gravel Size Gravel mean
Max Pore
Size Gravel area
Max Pore
Area
Max Pore
Diam
mesh in. in. in.2 in.2 microns
20/40 0.0234 0.003656 0.0004301 0.0000105 93
40/60 0.0117 0.001828 0.0001075 0.00000262 46
Pore size of the gravel is the limiter.
Remember the 1/3rd to 1/7th bridging
rule?
Damage Potential in the Gravel Pores
How many fines in 1 gram of 44 micron (325 mesh) particles?
Over 1 million!
Flow Capacity of Clean Screen
0
2
4
6
8
10
12
0 5000 10000
Flow Rate, BPD/ft
Pre
ss
ure
Dro
p, p
si
2-3/8"
2-7/8"
3-1/2"
Area open to flow
• 7” casing,
– 4 spf (0.6” hole) = 0.4%
– 12 spf (1” hole) = 3.6%
– 25 slots per foot (0.020” x 3”) = 0.57%
– 72 drilled holes (0.5”) per foot = 5.4%
– wirewrap screens = 6 to >10%
– woven screens = 20 to 30%
Sand Control Damage – The
Reasons
• Skin damage
– Reservoir-to-wellbore limits
– Invasion of fines into gravel
– Crushing/breaking of gravel
• Physical Damage
– Screen Running Damage
– Erosion during production
– Corrosion – from produced and injected fluids
Physical Damage
• Screen Running Damage
• Erosion during production
• Corrosion –produced and injected fluids
Primary Erosion Locations
• Directly opposite perforations
• sharp turns in the flow path
• where gas velocity is maximum
• eddy current and similar patterns
• constrictions in the flow path
Erosion holes
opposite
perforations
Max Velocities for Particle Sizes
0
50
100
150
0 100 200 300
Particle size, u
ma
x v
el. f
/se
c
0.1 ft3/day
1 ft3/day
Maximum flowing fluid velocity for increasing particle diameters.
Although smaller particles do less damage than larger particles (less
mass), the sheer number of small particles can still do a significant
amount of damage.
Baker Excluder Screen Damage from Trinidad
01/28/98
Upper shroud removed. Notice that the major damage is on the seam.
This type of damage can occur anywhere where a hot spot develops.
Weave Damage on an Eroded Screen
Poui B-12xxx Screen
January, 1988 (5 of 6 pictures)
Hole in screen can be seen Erosion hole in screen, adjacent holes
were plugged with debris.
Multiple damage mechanisms – A typical failure cause is when
the flow areas begin plugging with debris, followed by very
high velocity flow through a few remaining open flow areas.
The high velocity flow is what drives the site specific erosion.
Design Learnings
1. Crossover ports should have an area at least as large as the tubing
area, preferably 130%.
2. Crossover ports should be shaped to assist the slurry direction
change and minimize turbulence.
3. The area of the screen/casing annulus should be 20% larger than the
tubing – keep pressure drop below about 500 psi/100 ft.
4. Zones with very high permeability streaks may bridge the annulus
with dehydrated sand plugs – special design is required.
5. Never stand screens in the derrick.
6. Use a screen table to run.
7. Adequate make-up room needed at joints, but minimize blanks
where voids may occur.
Screen Tensile Strength
Screen Type Break tensile load
2-7/8” wire wrap 100 to 112,000 lb
2-7/8” welded 102 to 115,000 lb
3-1/2” wire wrap 100 to 149,000 lb
3-1/2” welded 140 to 155,000 lb
2-7/8” slotted liner 100,000 lb
Screen Collapse Loads
Screen types Collapse Load
2-7/8” wire wrap >8,000 psi
2-7/8” welded 5 to 6,000 psi
3-1/2” wire wrap >8,000 psi
3-1/2” welded 5 to 6,000 psi
Collapse loads
• Critical during high rate circulation and frac
packing
• Screen crush resistance may be reduced by
mechanical loading
Some Database Learnings
• Screen type as a failure factor in frac
packing is overshadowed by:
– Running damage to the screen
– Screen-to-casing clearances
– And, “maybe” how pack is placed after frac.
What screen do we use?
• Most of them. Carefully.
• Factors:
– formation grain size and sorting,
– mobile fines,
– how much gravel reserve can be placed,
– clearances
Total
number
wells of
complet
ion type
Total
Well-
Years
Sand
Control
Design
Failure %
of
attempts
Sand
Control
Applications
failure %
of attempts
Sand
Control
Infant
Failure
% of
attempts
Sand
Control
Production
Failure
(failures /
well/yr
Type of Completion
Injectors (soft sand formations) 24 63 0 12.5 0 0.064
Screenless Fracs 7 44 0 0 0 0.046
Cased and Perfed 66 306 0.00 1.5 0.00 0.085
Screen Only Completion 183 783 0.55 0.0 0.55 0.056
Expandable Screens 194 255 1 3 1 0.016
Cased Hole Gravel Pack 369 1514 0.00 2.2 0.8 0.011
Open Hole Gravel Pack 175 507 0.00 9.7 0.57 0.020
High Rate Water Packs 187 544 0.00 0.5 0.53 0.009
Frac Pack 844 3369 1.69 2.4 0.24 0.004
total wells 2049 7277.8