Wellbore damage or pluggingSurface handlingSubsea flowline plugging
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IS
Sand
Control
really
important
Why
?!!!
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Mohamed Wageih Mohamed
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Ali Mohamed Ali Hassan
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Ayman Mamdouh Abd Elkader
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TermBHN
Remarks
Unconsolidated
< 2
No cementing
material
Partially
2 - 5
Crushed with fingers
Friable
5 - 10
Crushed when
rubbed
Consolidate
10 - 30
Crushed with force
Hard> 30
Can not be broken
with force
Medium Hard
30 - 50
Hard
50 - 125
Very Hard
> 125
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Waleed Nagi Ebrahim
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Downhole
Surface
Blast Joints
Chokes
Gas lift Equipment
Elbows
Standing Valves
Tees
Pumps
Valves
Safety Valves
Metering Devices
Nipples
Flanges
Tubulars
Wellhead
:
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Ahmed Mohamed Hassan
Contents
1.Gravel types
2.Gravel sizing
3.Amount of gravel
4.Types of gravel pack
The heart of a gravel pack is the sizing of the gravel to stop
the formation sand. If the sand invades the pack, the 100 to 400
Darcy permeability level of the gravel pack drops to 50 to 500 md
and skins of 300 are possible.
gravel
Formation sand
flow
*
The gravel is selected and placed to stop the formation
sand.Correct size? About 6 times the diameter of the formation sand
in most cases, but there are some cases where larger gravel is
acceptable and more productive.
*
Sand:
roundness = 0.8
handling produces fines
Man made
roundness = 0.9+
larger average size in any range
Higher perm than sand
stronger, less fines.
For narrow range gravel about double price.
*
Conventional (Sauciers method)Sorting and fines as
influencesOrdering special gravels
It all begins with getting a particle size distribution from
several representative samples of each different segment of the
pay.
Use mesh screens if possible. Laser equipment over estimates
fines and under estimates the coarser particles.
*
95 microns is the 50% interceptSauciers method
6 x 50% intercept gives gravel that will not allow invasion of
grains into pack.
The 6 x is an experience factor but it is also describes the
maximum pore opening between a pack of similar sized grains.
Sorting influence can use 8x in frac pack or cases where sorting is
good and fines are limited.
*
Factors:
Length of perforated or open hole intervalAnnular dimensionsVolume
of perfsTarget for gravel outside the perfs
*
*
Advantages
known/trusted method
moderate reliability
Disadvantages
higher cost
subject to erosion
low reliability
moderately easily plugged
*
Proppant ( Gravel ) is precoated with resin material.Particles
are mixed with viscous gel and squeezed into the formation.A resin
coated gravel plug is left in the wellboreParticles are contacted
grain-to-grain.
Advantages
Low Cost, onshore.
Resin
Gravel
Formation
(Unconsolidated)
*
NOTES:
Only 5% of all Sand Control Treatments. Low Cost mainly done
onshore
In-situ or plastic consolidation: Involves the use of resins as
bonding material to cement the grains of formation sand several
feet around the wellbore, so that formation fluids can be produced
sand-free.
To be effective the resin must:
Wet the sand surfaces and adhere to the sand grains.
Yield a high compressive strength upon curing.
Not induce a high reduction of the permeability of the formation
around the wellbore.
In most cases a stimulation treatment (Mud Acid and/or Clay
Acid) is performed prior to the consolidation treatment.
GP sand is (by design) 5-6 times larger than formation sand.
GPing does not alter screen behavior. GPing will arrest annular
flow GP screen must allow production of fines, otherwise completion
will plug. Pore throat of most GP sands will restrict production of
fines. GPing will arrest/trap formation filter cake on the
formation surface.GPing will not allow formation to
relax/de-stress.
Particle size
of produced
fines: 7 u
Particle size
of produced
fines: 30-60 u
Particle size
of produced
fines: 80-100 u
Screen
Formation
GP sand
2
*
Reverse-circulation:
Gravel laden fluid -annulus-screens-flow back up the tubing
Disadvantages:
Poss. of rustdebris from annuls mixed gravelDamage pack perm
Crossover:
Gravel laden fluid tubing screen open hole annulus-leave gravel
annulus - flow back up the annulus
Note:
All OH are underreamed through the productive interval to insure
well productivity
*
High rate water packing is a method of sand control where
fracturing the formation is employed to place gravel outside of the
casing and perforations beyond the damage radius of the well
Advantages:
pressured packing of perfs
easier design/apply than frac pack
Good flow in mod. kh formations
Disadvantages:
lower flow capacity than frac
limited zone/water control
Unequal packing of gravel per foot
Injection rate rule of thumb: 1 bpm/10 ft of perfs
High well productivity losses typically 60% - are observed
after well killing followed by gravel packing operations see the
next figure.The next figure summarizes the result of a field test
in which the wells productivity index was measured at various
stages in the completion process. The final well productivity,
despite a 6-month clean up period, was only 18% of that achieved
prior to gravel packing.
There is a varying efficiency for the different types of sand
control that can be installed. Typical well productivity and the
implications for the various sand control options for a West
African field study are:
