3333rdrd IEAEOR SymposiumIEAEOR Symposiumy py pA u g u s t 2 6 ‐ 3 0 , 2 0 1 2
presenter: Hydrophobically Modifiedpresenter:D. Rousseau
Hydrophobically Modified Polymers for IOR: Controlling Injectivity Through Thickening
authors:G. Dupuis (Poweltec),D Rousseau (IFP Energies nouvelles)
Ability and/or Flow‐induced Gelation
D. Rousseau (IFP Energies nouvelles),R. Tabary (IFP Energies nouvelles),B. Grassl (IPREM‐EPCP)
Session 2: Theme BMonday August 27thy g
Introduction 1/5Context: polymers for mobility control and permeability reduction
polymers for mobility control(polymer flooding, SP, ASP)
l t b t ff ti polymer
oiloil
polymers to be more cost-effective(optimum viscosity / concentration)
polymers to be more stable(temperature, salinity, mech. degradation) inj. well
polymerinjectionwater
injectioninj. well(temperature, salinity, mech. degradation)
minimum adsorption is required
polymers for permeability reduction polymers for permeability reduction (well treatments ─water shutoff, injection profile control─ , conformance control) polymers to be more stable
(temperature, salinity, mech. degradation) controlled adsorption or controlled in-situ gelation
is requiredDi ti t P bilit R d ti bilit i
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Disproportionate Permeability Reduction ability is advantageous
Introduction 2/5HMWSP
Hydrophobically Modified Water Soluble Hydrophobically Modified Water Soluble Polymers (HMWSP)Polymers (HMWSP)
polymers with hydrophilic backbones bearing hydrophobicpolymers with hydrophilic backbones bearing hydrophobic units capable of creating physical bonds (hydrophobic
nanodomains) between each other ("associative" polymers)
hydrophobic nanodomain
C hydrophobic side-group
hydrophilic backbone
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Introduction 3/5Advantages of HMWSP
Thickening agents (mobility control) sharp increase of viscosity above "caccac"
(Pa.
s) HMWSP
less chemicals required for a given mobility reduction high salinity : preservation/increase of viscosity shorter chains (~low Mw) Vi
scos
ity (
WSP
increased resistance to mechanical degradationConcentration (g/mL)
Permeability reducing agents (well treatments, conformance control)
"multilayer" adsorption on surfaces or flow-induced gelation in porous media marked and stable permeability reduction
WSP
4 33rd IEAEOR Symposium33rd IEAEOR Symposium – August 26-30, 2012HMWSP
Introduction 4/5Brief state of the art
M bilit t l Mobility control HMWSP considered as mobility control agents since ~1980 (Exxon Mobil, Chevron,
Dow Chemical – reviews by Taylor and Nasr-el-Din 1998 & 2007)
f ff C OOC ( ) ( renewed interest in the past years: first offshore pilot by CNOOC (~2007) (BoHai bay, China),
HMWSP were selected thanks to their satisfactorily behavior (viscosity) in the available
M bilit t l d i d th f t l
satisfactorily behavior (viscosity) in the available brines: mixture of see water, soft water and produced water with specific salinity/hardness
Mobility control and in-depth conformance control feasibility study for heavy oil in western Canada (2012) (from CNOOC)(from CNOOC)
Well treatments Halliburton (Eoff, Dalrymple & Reddy): patents,
publications and significant successes in field li ti ("W t b" )
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applications ("Waterweb" process)
to date, HMWSP remain mainly used for well treatment operationsto date, HMWSP remain mainly used for well treatment operations
Introduction 5/5Motivations & objectives of the present study
Our previous works Synthesis and characterization of an extensive set of HMWSP and WSP with
identical hydrophilic backbones11
enables "true" comparative assessments between HMWSP and WSP Flow in porous media of dilute HMWSP solutions22
(to minimize the role played by "rheology" and to focus on adsorption) high Resistance Factors due to adsorption of minority polymeric species high Resistance Factors due to adsorption of minority polymeric species minority polymeric species can be removed by proper pre-filtration procedure
(also likely through optimization of the synthesis process)
The present study: flow in porous media of semi-dilute HMWSP solutions viscosity in the range of viscosity for mobility control applications
filt ti i d t i it i ( h ibl ) pre-filtration in order to remove minority species (as much as possible) impact of HMWSP rheology on their propagation in porous media
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11 : G. Dupuis, et al., Anal. Chem., 2009, 8181, 8993–9001.22 : G. Dupuis, et al., SPE Journal (vol. 1616--11, March 2011 – SPE-129884-PA).
Outline
Introduction Introduction
Polymers and aqueous solution properties
M b filt ti Membrane pre-filtration
Coreflood experiments
Summary
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Outline
Introduction Introduction
Polymers and aqueous solution properties
M b filt ti Membrane pre-filtration
Coreflood experiments
Summary
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Polymers and aqueous solution properties
" t d d b i " Polymers studied: Sulfonated-PAMwith Mw = 1.3-1.4 106 g/mol WSP: 20 mol-% AMPS, 80 mol-% AM
HMWSP 5 l % AMPS 94 5 l % AM 0 5 l0 5 l % AMC12% AMC12
"standard brine":20 g/L NaCl
HMWSP: 5 mol-% AMPS, 94.5 mol-% AM, 0.5 mol0.5 mol--% AMC12% AMC12
Relative viscosity
HMWSPWSP
HMWSPWSP
Relative viscosity aimed : r0 ~ 20 WSP
= 24 5
Aimed viscosityAimed viscosity
r0 = 24.5
Cp = 9.8 g/L
HMWSPFiltered solutions used for
coreflood experimentsFiltered solutions used for
coreflood experimentsr0 = 17.8
Cp = 3.4 g/L
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Outline
Introduction Introduction
Polymers and aqueous solution properties
M b filt ti Membrane pre-filtration
Coreflood experiments
Summary
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Membrane pre-filtration
HMWSP Rm curve
S
-2- Channels opening
-3- Gel filtration
HMWSP Rm curve
S
-2- Channels opening
-3- Gel filtration
2-steps pre-filtration on 3µm Millipore-MF
b
HMWSP BT curve
WSP BT curve
WSP R
-1- Gel initiationHMWSP BT curve
WSP BT curve
WSP R
-1- Gel initiation
membranes: 30 s-1 and 3 s-1
WSP Rm curve
HMWSP TOC C/C0
WSP Rm curve
HMWSP TOC C/C0
STEP 2 (3 s-1)
WSP: good filterability HMWSP: complex behavior
"gel filtration" process with channels openning
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g p p g 100% HMWSP concentration in the effluents (TOC) "acceptable" filterability"acceptable" filterability
Outline
Introduction Introduction
Polymers and aqueous solution properties
M b filt ti Membrane pre-filtration
Coreflood experiments
Summary
12 33rd IEAEOR Symposium33rd IEAEOR Symposium – August 26-30, 2012
Coreflood experiments 1/6 Experimental conditions and procedures
SiC (silicon carbide) granular packs 3 permeabilities investigated
SiC grain size d (µm) 5050 8080 150150SiC grain size, dg (µm) 5050 8080 150150
Permeability, k (10-12 m²) 1.0 1.0 ±± 0.10.1 2.5 2.5 ±± 0.10.1 11.0 11.0 ±± 0.50.5
Porosity, (%) 41 41 ±± 0.50.5 41 41 ±± 0.50.5 41 41 ±± 0.50.5y, ( )
Hydrodynamic pore throat radius, rp (µm)5.0 5.0 ±± 0.50.5 8.0 8.0 ±± 0.50.5 17 17 ±± 11
/815.115.1 , krr cpp
core holder with intermediate pressure taps: P measured on 3 sections "external damage" and "in-depth propagation"
E S1 S2
flow
direction
E S1 S2
flow
direction
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1 cm
0 cm 5 cm 9 cm
10 cm1 cm
0 cm 5 cm 9 cm
10 cm
Coreflood experiments 2/6 Experimental conditions and procedures cont'd
Injection conditions 100% standard brine saturation T = 30°C fixed initial wall shear rate (velocity gradient) : wall = 15 s-1
(provides only an estimation of the shear rate) flow rates: Q = 2 to 7 mL/h or interstitial velocities: ui = 0.7 to 2.3 m/day
.
pipwall rurSQ /4)/(4
Procedure initial permeability determination
Q i y
p y polymer injection @ Q mobility reduction: Rm (or RF) = Ppolymer / Pbrine_initial
brine injection @ Qbrine injection @ Q brine injection @ various flow rates "irreversible" perm. reduction: Rk (or RRF) = Pbrine_final / Pbrine_initial
estimation of the polymer adsorbed thickness:
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estimation of the polymer adsorbed thickness: h)1( 4/1 Rkrph
Coreflood experiments 3/6 WSP in a 1 Darcy core
BT curveBT curve
E S1 S2
Expected behavior: Rm ~ r0, quick breakthrough slight increase on section E: entry-face effect
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Coreflood experiments 4/6 HMWSP in a 1 Darcy core
Gel initiationGel propagationon section S1
Pressure transducerout of range
Gel initiationGel propagationon section S1
Pressure transducerout of range
Gel initiationGel propagationon section S1
Pressure transducerout of range
Gel initiationon section E
on section S1Gel initiationon section E
on section S1Gel initiationon section E
on section S1
E S1 S2E S1 S2
up to 1 25 PVI: Rm @ 1 9 PVI: gel propagation up to 1.25 PVI: Rm ~ r0
viscous front propagation (& likely monolayer adsorption)
@ 1.25 PVI: ~103 Rm on section E, Rm on S1 and S2
@ 1.9 PVI: gel propagation on section S1 not (only) an external filter-cake
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@ 1.25 PVI: 10 Rm on section E, Rm on S1 and S2 our interpretation = flowflow--induced gelationinduced gelation significant amount of polymer retained in the gel
≠ ≠ as in the diluted as in the diluted regime! (with regime! (with
minority species)minority species)
Coreflood experiments 5/6 HMWSP in cores with variable permeability
Gel initiation
k = 1 Darcy; rP = 5 µm
Gel initiation
k = 1 Darcy; rP = 5 µm 2.5 and 11 D cores: no flow-
induced gelation (up to 20 PVI)initiation
k = 2.5 Darcy; rP = 8 µm
k = 11 Darcy; rP = 17 µm
E
initiationk = 2.5 Darcy; rP = 8 µm
k = 11 Darcy; rP = 17 µm
E
experiments were all performed at the same initial wall shear rate:wall = 15 s-1.
flow induced gelation flow induced gelation seems to be triggered byseems to be triggered by
wall
Gel initiation on section E
k = 1 Darcy; rP = 5 µm
k = 2.5 Darcy; rP = 8 µm
Gel initiation on section E
k = 1 Darcy; rP = 5 µm
k = 2.5 Darcy; rP = 8 µm
Gel initiation on section E
k = 1 Darcy; rP = 5 µm
k = 2.5 Darcy; rP = 8 µm
seems to be triggered by seems to be triggered by "confinement" (pore "confinement" (pore size) rather than by size) rather than by hydrodynamics:hydrodynamics:5 µm < r5 µm < r CC < 8 µm< 8 µm
Gel propagation on
k = 11 Darcy; rP = 17 µm
S1Gel propagation on
k = 11 Darcy; rP = 17 µm
Gel propagation on
k = 11 Darcy; rP = 17 µm
S1
5 µm < r5 µm < rppCC < 8 µm< 8 µm
(kinetics aspects remains to (kinetics aspects remains to be studied in details)be studied in details)
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Gel propagation on section S1
Gel propagation on section S1
Gel propagation on section S1
be studied in details)be studied in details)
Coreflood experiments 6/6 Irreversible permeability reductions
WSP (k = 1 Darcy)WSP (k = 1 Darcy)WSP (k = 1 Darcy)
HMWSP (k = 2.5 Darcy)HMWSP (k = 2.5 Darcy)HMWSP (k = 2.5 Darcy)
S1S1
...
Permeability reduction (Rk) of HMWSP can be assessed only when no gel is formed
HMWSP adsorption = moderated to low: hHMWSP < h
WSP
pre-filtration was efficient to remove "minority species"
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flow-induced gelation does not seem to be induced by the build-upof adsorbed HMWSP multilayers
Outline
Introduction Introduction
Polymers and aqueous solution properties
M b filt ti Membrane pre-filtration
Coreflood experiments
Summary
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Summary
This study was performed on 1 particular class of HMWSP, with "low" Mw This study was performed on 1 particular class of HMWSP, with "low" Mw ((101066 g/molg/mol) and "high" hydrophobe content () and "high" hydrophobe content (0.5 mol0.5 mol--% monomers with C12% monomers with C12))
Membrane filtration of these HMWSP leads to formation of a filter-cake and Membrane filtration of these HMWSP leads to formation of a filter cake and a rater complex gel-filtration process but filterability remains acceptable (channel opening mechanism)
Flow of these HMWSP in a core can lead to flowflow--induced gelationinduced gelation with significant retention of polymer within the gel with inin--depthdepth propagation of the gel
Permeability (i.e. porePermeability (i.e. pore--throat size, for granular media)throat size, for granular media), rather than hydrodynamics, appears as a critical parameter to trigger flow-induced gelation flow-induced gelation occurs only if permeability is low enough 5 µm < rp
C < 8 µm
Permeability threshold as well as gel strength will obviously strongly depends of Permeability threshold as well as gel strength will obviously strongly depends of HMWSP chemical compositionHMWSP chemical composition
5 µm < rp < 8 µm
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Fine-tuning of HMWSP behavior in porous media is mandatory to ensure the success of mobility control and/or permeability reduction operations