Table Of ContentLOW SALINITY AND
ENGINEERED WATER
INJECTION FOR
SANDSTONE AND
CARBONATE RESERVOIRS
LOW SALINITY AND
ENGINEERED WATER
INJECTION FOR
SANDSTONE AND
CARBONATE RESERVOIRS
EMAD WALID AL SHALABI
Khalifa University of Science and Technology, The Petroleum
Institute,AbuDhabi,UAE
KAMY SEPEHRNOORI
The University of Texas at Austin, Texas, USA
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DEDICATION
To my beloved parents Walid and Fatin, dear brother Eyad, and
lovely sisters Nancy, Nadia, and Noor, for their endless love,
patience, inspiration, support, and encouragements.
Emad Walid Al Shalabi
To my brother Dr. Darius S. Noori.
Kamy Sepehrnoori
LIST OF FIGURES
Figure 1.1 Oil recovery mechanisms during the life of an oil 2
reservoir
Figure 2.1 Wettability alteration proposed mechanisms 11
Figure 2.2 Effect of seawater injection on oil recovery from chalk 12
cores compared to formation water both
spontaneously and using forced displacement
Figure 2.3 Oil recovery curve for the first coreflood of Yousef 13
et al. (2011)
Figure 3.1 Remaining oil saturation post low salinity waterflood 20
Figure 3.2 Saturation profile for both high and low salinity water 21
flooding based on Buckley(cid:1)Leverett theory
Figure 3.3 Water cut development with connate water banking 21
between November 1994 and March 1995
Figure 3.4 Comparison of field-measured tracer concentration 23
profiles between Stage 1 (field seawater) and Stage 3
(SmartWater—10 times diluted) for Well A
Figure 4.1 Timeline of the low salinity proposed mechanisms 26
Figure 4.2 (A) Schematic of electric double layer and oil 31
components adsorbed to the divalents through the
double layer; (B) the thickness of double layer when
high-salinity water is in contact with the clay surface;
(C) the thickness of double layer when low salinity
water is in contact with the clay surface
Figure 4.3 Advancing contact angle measurements on calcite, 34
dolomite, and magnesite under various conditions
Figure 4.4 Proposed mechanisms for wettability alteration in 35
carbonate rocks
Figure 4.5 IFT measurement of reservoir live-oil with different 37
dilutions of seawater
Figure 4.6 Contact angle measurement of reservoir live-oil with 38
different dilutions of seawater
Figure 4.7 NMRT distribution for a rock sample before and 38
2
after the coreflood experiment
Figure 4.8 Wettability alteration by dissolution 41
Figure 4.9 pH-induced wettability alteration 42
ix
x ListofFigures
Figure 4.10 Flow chart of LSWI mechanism in carbonates 43
Figure 4.11 Flow chart of EWI mechanism in carbonates 45
Figure 5.1 Cumulative oil recovery match with the empirical 57
LSWI model
Figure 5.2 Relative permeability curves with the empirical LSWI 57
model
Figure 5.3 CDC model used in the Fundamental LSWI Model 59
Figure 5.4 3D map of remaining oil saturation at 6 injected PV 60
(Quarter 5-spot Model-LSWI Cycle)
Figure 5.5 Fractional flow curves (empirical LSWI model-quarter 61
5-spot field model)
Figure 5.6 Fractional flow curves analysis for seawater (first) and 62
low salinity water (second) injection cycles
Figure 5.7 Total relative permeability calculations at the oil bank 63
front saturation for different injection cycles
Figure 5.8 Effect of design parameters on cumulative oil recovery 64
Figure 5.9 3D surface of cumulative oil recovery at varied values 64
of LSWI slug size (PV) and injected water salinity
(meq/ml)
Figure 6.1 Equilibrium in water/oil/naphthenic acid systems at 83
low pH
Figure 6.2 Simplified UTCOMP calculation flowchart 89
Figure 6.3 Simplified UTCOMP(cid:1)IPHREEQC calculation 96
flowchart with the hydrocarbon phase effect on the
aqueous(cid:1)rock geochemistry
Figure 6.4 Simplified UTCOMP(cid:1)IPHREEQC calculation 97
flowchart without the hydrocarbon phase effect on
the aqueous(cid:1)rock geochemistry
Figure 6.5 Sulfate ion concentration using UTCHEM and 102
PHREEQC-fluid species
Figure 6.6 Anhydrite concentration at different injection cycles 102
Figure 6.7 Effective molar Gibbs free energy calculated for 104
corefloods of Yousef et al. (2011) using the
mechanistic LSWI model
Figure 6.8 History matched sulfate concentration for coreflood of 105
Chandrasekhar and Mohanty (2013) using the
mechanistic LSWI model
ListofFigures xi
Figure 6.9 Equivalent fraction of SO -X and CH3COO-X at 106
4 2
gridblock (1, 1, 1)
Figure 6.10 Total change in porosity profile 107
Figure 6.11 Total change in permeability profile 107
Figure 7.1 Summaryof injection-water chemistry in different 114
EOR/IOR processes
Figure 7.2 pH number using PHREEQC-fluid species 121
(LSWI, CO , and LSWI1CO )
2 2
Figure 7.3 Dolomite concentration at different injection cycles 121
(LSWI, CO , and LSWI1CO )
2 2
Figure 7.4 Anhydrite concentration at different injection cycles 122
(LSWI, CO , and LSWI1CO )
2 2
Figure 7.5 Comparison between SW, LSWI (SW/20), miscible 123
CO , and SWAG (LSWI-SW/201CO )
2 2
Figure 7.6 Cumulative oil recovery for SWAG experiments in the 124
tertiary mode
Figure 7.7 Fractional flow curves for miscible CGI 125
Figure 7.8 Total mobility curves for miscible CGI 126
Figure 7.9 Fractional flow curves for SWAG (SW1CO ) 126
2
Figure 7.10 Total mobility curves for SWAG (SW1CO ) 127
2
Figure 7.11 Fractional flow curves for SWAG (LSWI1CO ) 127
2
Figure 7.12 Total mobility curves for SWAG (LSWI1CO ) 128
2
Figure 8.1 Variation of zeta potential with pH of two carbonate 135
rocks and calcite tested in deionized water
LIST OF TABLES
Table 5.1 Summaryof the six proposed LSWI history matching 55
methods
Table 5.2 Two-level fractional factorial design parameters 63
Table 5.3 LSWI-SWCTT plan 69
Table 7.1 Relative permeability parameters used for constructing 125
fractional flow curves for SWAG (SW, LSWI) and
miscible CGI processes
Table 7.2 M and ms calculations for SWAG (SW, LSWI) and 128
miscible CGI processes
Table 8.1 Summaryof main LSWI/EWI corefloods in carbonates 137
and sandstones
xiii
CHAPTERONE
Introduction to Enhanced Oil
Recovery Processes
Content
References 5
Different recovery mechanisms are involved during the life of an oil reser-
voir, including primary, secondary, and tertiary mechanisms. Primary
recovery includes oil recovery by natural drive mechanism, including solu-
tiongas,water influx,gascapdrives,andgravitydrainage.Theconventional
primaryrecoveryrangesfrom3%originaloilinplace(OOIP)withthehelp
oftheexpansionofundersaturatedoilto15%OOIPwithsolutiongasdrive.
Inthe secondary recovery phase, different process are usedtoraise or main-
tain reservoir pressure, such as gas or water injection. The presence of an
activewaterdriveoragascapdrivebooststherecoverysignificantlytoabout
50% or more of the OOIP by maintaining the reservoir pressure via gas or
water injection(GuerithaultandEconomides,2001;Lake,1989).
Mostoftheaveragepressureofoilreservoirsisdepletedduringthepri-
mary and secondary recovery phases. As a result of this pressure depletion,
alargefractionoftheOOIPisleftbehindinthereservoir.Differentmeth-
ods are suggested to recover the remaining oil in economic and environ-
mental approaches (Dandona and Morse, 1972). For the tertiary recovery
phase, enhanced oil recovery (EOR) methods are used to improve the oil
recovery beyond primary and secondary recoveries in an economic way
under certain market and technology conditions. The EOR is the oil
recovery by injection of fluids that normally do not exist in the reservoir,
which excludes pressure maintenance or waterflooding. This definition
doesnotrestricttheapplicationofEORtoaparticularphase(primary,sec-
ondary, or tertiary) (Lake, 1989). Different EOR techniques are being
used, including solvents such as miscible and immiscible gas flooding
(hydrocarbon, carbon dioxide, or nitrogen), chemical flooding (surfactant,
polymer, or alkaline), thermal methods (steam flooding, cyclic steam
LowSalinityandEngineeredWaterInjectionforSandstoneandCarbonateReservoirs. Copyright©2017ElsevierInc.
DOI:http://dx.doi.org/10.1016/B978-0-12-813604-1.00001-8 Allrightsreserved. 1
2 LowSalinityandEngineeredWaterInjectionforSandstoneandCarbonateReservoirs
flooding, or in-situ combustion), and others [microbial, low salinity/engi-
neeredwater injection(LSWI/EWI),oracoustic].
Improved oil recovery (IOR) is another term that has been used inter-
changeably or even replaced the EOR term. IOR refers to any process
that improves oil recovery; hence, this definition includes EOR processes
as well as other practices such as waterflooding, pressure maintenance,
infill drilling, and multilateral wells. Fig. 1.1 shows the different recovery
mechanisms during the life of an oil reservoir.
Waterflooding has been considered as the most commonly used sec-
ondary oil recovery technique since 1865. Recently, a tertiary effect of
this technique has been observed depending on the composition and
salinity of the injected water. LSWI/EWI is one of the emerging IOR
techniques for wettability alteration in both sandstone and carbonate
reservoirs. The popularity of this technique is due to its high efficiency in
displacing light-to-medium gravity crude oils, ease of injection into oil-
bearing formations, availability and affordability of water, and lower capi-
tal and operating costs involved. The latter advantages lead to favorable
economics compared to other IOR/EOR methods.
The LSWI/EWI IOR technique is also known in the literature as
LoSal by BP,Smart WaterFlood by Saudi Aramco,Designer Waterflood by
Figure1.1 Oilrecoverymechanismsduringthelifeofanoilreservoir.
