Unconventional fracturing fluids what, where and why

Unconventional Fracturing Fluids : What,
Where and Why
D.V. Satya Gupta
Tomball Technology Center
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A Wide Range of Fluid Systemsgy
• Water-Based Polymer Systems
Sf t tSt• Surfactant Systems
• Energised Systems
• Emulsion Systems• Emulsion Systems
• Non-aqueous Systems
– Oil-Based
– Methanol
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g y



A
Wide Ran
g
e of Fluid S
y
stems
• Why So Many Fluids?
Diff t F ti
–
Diff
eren
t F

orma
ti
ons
• Base Lithology
• Additional Mineral Components
– Different Formation Fluids
– Different Objectives
Different P mping Config rations
–
Different P
u
mping Config
u
rations
–Etc.
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Conventional Frac Fluids
• Water Based Polymer Systems
Wt ith F i ti R d
–
W
a
t
er w
ith F
r
i

c
ti
on
R
e
d
uce
r
– Base Gel
–
Crosslinked Water Based Fluid
• Borate Crosslinked
• Zirconium Crosslinked
High pH and Lo pH Fl ids
–
High pH and Lo
w
pH Fl
u
ids
– Low Polymer Systems
–
Ener
g
ized S
y
stems
g y
– Foams
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Wate
r
-Based Pol
y
mer S
y
stems
• Low Residue
• Base Fluid (Water) Is Inexpensive
• Continuous or Batch Mix
• Excellent Rheological Properties
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Wh
y
Unconventional Fluids
• Tight Gas Wells
U ti l W ll
–
U
nconven
ti
ona
l W
e
ll

s
• Shales
• Coal Beds
• Wells with Adverse Capillary Effects
– Sub-irreducible Water Saturation
Sb
i d ibl H d b S t ti
–
S
u
b
-
i
rre
d
uc
ibl
e
H
y
d
rocar
b
on
S
a
t
ura
ti
on

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ights Reserved. © 2010 Baker Hughes Incorporated. All R
Technical paperspapers

Water Sensitive Reservoirs
• Clay expansion - Smectite and mixed-layer clays are
water sensitive (swelling and fines migration)water-sensitive (swelling and fines migration).
• Clay dispersion - “water shock,” or “salinity shock.” : the
dispersion of poorly-cemented clays, such as some of thep p y y
more fragile versions of illitic clays or pore-filling kaolinite.
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Undersaturated Gas Reservoirs
• Capillary undersaturation:
iiti l t t ti i l th ld b td d
–
i
n
iti
a
l
wa
t
er sa
t
ura
ti
on
i

s
l
ess
th
an wou
ld b
e expec
t
e
d
un
d
er
capillary equilibrium or irreducible water saturation
– also called sub-irreducible water saturation
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Ti
g
ht Gas Reservoirs
• Aqueous Phase Trapping - Hydrocarbon permeability is
frequently reduced due to imbibition of aqueous treatment
frequently reduced due to imbibition of aqueous treatment
fluids during well operations. This imbibition effect has
been observed as a particularly severe problem in
reservoirs where a sub-irreducible water saturation exists.
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q pp g

Aq
ueous Phase Tra
pp
in
g
• Understanding aqueous phase trapping is important due
to it being the driving force behind many low
permeability
to it being the driving force behind many low
-
permeability
stimulation decisions.
• Dia
g
nostic tools can be used in evaluatin
g
sensitivit
y
to
g g y
aqueous phase trapping.
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Relative Permeability Decreases Due to Water
Imbibition
Imbibition

70
80
90
10 0
e
nt
K rw
K rg
40
50
60
70
Permeability, perc
e
R e la tiv e p e r m e a b ility
d ecreases r a p id ly as W a te r
S a tu ra tio n in creases .
10
20
30
40
Relative
0
0 2 0 4 0 6 0 8 0 1 0 0
W a te r S a tu ra tio n , P e rc e n t P o re S p a c e
W a te r
Im bibition
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q

Remediation or Prevention Techni
q
ues
• Adding methanol to water-based treatments to reduce
water content lower interfacial tension and enhance the
water content
,
lower interfacial tension
,
and enhance the
evaporation of the water-based filtrate during reservoir
cleanup
• Use of non-aqueous fluids (methanol-based, oil-based, or
gas-based) to eliminate water injected into the formation
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Unconventional Frac Fluids
• Polymer Systems
A M th l B d
–
A
queous
M
e
th
ano
l B

ase
d
– Non-Aqueous Methanol Based
•
Non Polymer Systems
Non Polymer Systems
– Surfactant Gels (VES)
– VES Foams
– Hydrocarbon Based
– Liquid CO
2
Based
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q


Li
q
uid CO
2
Based Emulsion
2
• Minimize Water In Formation
25% ll d fl id
–
25%
ge
ll
e
d fl

u
id
• 40% Methanol
• Low Residue
• Rapid Clean Up
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ess da a t a ea e s
y



Gelled Methanol S
y
stems
• 100% Gelled Methanol
–
Good for water
-
sensitive formations
Good for water
sensitive formations
• Low Surface Tension - Better Flowback
• Vapor Density
• New Gelling / Crosslinking Systems
– Easier to break
CO
tibl
–
CO
2

compa
tibl
e
– Wide temperature range
–
L
ess da
m
ag
in
g t
h
a
n
ea
rli
e
r
syste
m
s
g g syste
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q

Crosslinked Non-
Aq
ueous Methanol
• Water Sensitive Formations
DG W ll

•
D
ry
G
as
W
e
ll
s
• Wells Damaged with Water
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y

Surfactant S
y
stems
• Cationic + Salt
A h t i S lt
•
A
mp
h
o
t
er
i
c +
S
a
lt

• Cationic + Anionic
•
Anionic
•
Anionic
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VES S
y
stem
• Two Surfactant System
Cti i Ai i
–
C
a
ti
on
i
c +
A
n
i
on
i
c
• Simple
–
Two fluids added on

-
the
-
fly
Two fluids added on
the
fly
• Formation Benign
– No residue, no formation damage
• Low Surface Tension
– No additional flow-back surfactant is needed
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VES S
y
stem
• The System does not require
Bi id Cl C t l A t
–
Bi
oc
id
e or
Cl
ay
C
on

t
ro
l A
gen
t
– Buffer
•
Insensitive to salinity
Insensitive to salinity
• Flowback fluid can be reused
• Compatible with N
2
and CO
2
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y

VES S
y
stem
• Shallow Gas Projects
• Tight Formations
• Maximize Fracture Conductivity
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eserved.
ProppantProppant
ProppantProppant

PackPack
Clean up ofClean up of
Clean up ofClean up of
VES FluidVES Fluid
SystemSystem
Showin
g
NoShowin
g
No
DamageDamage
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–
y


Foamed VES S
y
stem
• Two Surfactant System
NR id
•
N
o
R
es
id
ue
• Strong Self-Foaming Ability
–

No additional foamer needed
No additional foamer needed
• Cost Effective
• Foam Viscosit
y
: Same as Conventional Foams and also
y
adjustable
• High Quality Foams (>85 Quality) with Light Weight
Proppants
Proppants
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Foamed VES Systemy
• Medium to High Temperature
Ud P dG Wll• Under Pressured Gas Wells
• High Permeability Wells
• Wells with Complex Fracture Issues• Wells with Complex Fracture Issues
• Coal Bed Methane Wells
• High Quality Foams for Shales gQ y
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y


CO
2
S
y
stems
2
• Liquid CO

2
CO
/N
•
CO
2
/ N
2
• Unconventional CO
2
Foam
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