MSc Reservoir Evaluation and Management Project Report 2013/2014 Nestor Danilo Vasconez Noguera 1D core flood modelling of impact of brine composition and distribution of exchanger sites on optimisation of low salinity waterflooding Heriot-Watt University Institute of Petroleum Engineering Supervisor – Professor Eric Mackay
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MSc Reservoir Evaluation and Management
Project Report 2013/2014
Nestor Danilo Vasconez Noguera
1D core flood modelling of impact of brine composition and distribution of
exchanger sites on optimisation of low salinity waterflooding
Heriot-Watt University
Institute of Petroleum Engineering
Supervisor – Professor Eric Mackay
DECLARATION:
I……………………………………………………………………………………………… confirm that this work submitted for
assessment is my own and is expressed in my own words. Any uses made within it of the works of
other authors in any form (e.g. ideas, equations, figures, text, tables, programs) are properly
acknowledged at the point of their use. A list of the references employed is included.
Signed……………………………………………
Date………………………………………………
ACKNOWLEDGEMENTS
The author is thankful to the Institute of Petroleum Engineering at Heriot‐Watt University for
providing me all the necessary facilities to successfully develop the present project. Thank you to
Professor Eric Mackay for his guidance, support and knowledge shared through all the steps of the
project. Finally, the author is grateful to CMG for providing the licenses and last version of GEM.
SUMMARY
The present report contains a literature review of the key and latest publications on Low
Salinity Waterflooding (LSWF) since its real development in the 1990`s to explain the
dominant mechanisms, modelling processes and requirements to apply this Enhanced Oil
Recovery (EOR) technique. Up-to-date, there is no general agreement of the dominating
mechanism that rules the LSWF effectiveness. Currently, wettability alteration to a more
water-wet state of the rock as a result of ion exchange and/or double layer expansion
mechanism are the two most feasible and supported pore scale mechanisms. However, most
of the last published modeling methods are trying to represent the wettability changes only as
a result of Multi-Ion Exchange (MIE) processes and geochemical reactions. These methods
cross-check their results with observed laboratory data and with the chemical reactions
obtained from a recognized geochemical simulator, PHREEQ-C (Kharaka et al., 1988). The
present project is oriented to reproduce the experimental results obtained in the IPE laboratory
at Heriot Watt University with standard industry reservoir simulation software and validate
the outcomes with PHREEQ-C to later define correlations between grid size, cation exchange
capacity (CEC), selectivity coefficients, injection rates, and oil recovery in a MIE modelling
The same model was used to observe the impact of LSW in tertiary mode. Initially Formation
Brine concentration was injected and after 10 pore volumes when the model was at High
Salinity residual oil saturation, low salinity brine was injected. The results show that K and
Mg produce the earliest increase in recovery followed by Na and Ca. (See Figure 34)
Figure 34. Low salinity water injection in tertiary mode.
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DISCUSSION
Results – Single Phase
Experimental data match
The match was obtained by varying the rock CEC and the selectivity coefficient of the rock.
The final value for the CEC is 350 meq/L with 20 cells while the selectivity coefficients are
0.5, 0.4, and 0.12 for Na - Ca, Na - Mg and Na - K exchanges respectively.
The CEC of the rock can be translated into meq/(100 grams of rock) to relate its value to
petrophysical dimensions (Mian al, et., 1986):
CECQ ∙ 100 ∙ φ1 φ ∙ ρ
Where
CEC
;φ fractionalporosity;ρ sandgraindensity
By doing so, the CEC of the rock is 3.09 meq/(100 grams of rock) which is in the range of
rocks with kaolinite content (Ramirez al, et., 1990). However, no additional data is available
to confirm this.
The reduction in the selectivity coefficient for the Na-K ion exchange helps to reproduce the
K concentration in the effluent especially the increase after 10 PV to around 23 ppm of K
concentration. However, the sustained behaviour between 1 and 10 PV is not reproduced by
GEM or PHREEQ-C. Additional considerations in terms of mineral reactions will be needed
to capture this response from the system.
The selectivity coefficient of 0.12 is interpreted as the ratio of ions on the exchange site which
means that K is more preferred than Na on the clay surface. This could partially explain the
increase in K ions on the rock and the later detachment observed in the effluent.
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Grid resolution
The statement presented in the results suggests a method to upscale the CEC of the rock when
it comes to refine or coarsen a grid. As such, if the grid cell sizes between injector and
producer wells are reduced to a half, the CEC has to be doubled in order to maintain the ion
exchange process of the rock and do not alter the interpolated relative permeability and/or
capillary pressure curves used. However, this observation is only supported at core scale
based on experimental observations and only numerically at field scale due to the lack of data.
Rate sensitivities
The injection rates at core scale are highly dependent on the pore volumes of the cells to
which the injector well is connected. At core scale, the higher the rates, the more important
the compositional and molar changes per time step which can be translated in numerical
convergence issues. An additional statement related to the ion exchange independence of
injection rates is proposed as no variations in the matched effluent concentrations were
observed at core and field scale supported only by core scale observations. However, the
author is aware that additional heterogeneities together with diffusion and dispersion
phenomena have to be considered when modelling at larger scale.
Phreeq-C comparison
The results are comparable against Phreeq-C outcomes and show an improvement in the
calcium and magnesium concentration match compared to the proposed model by PHREEQ-
C. This gains significance as previously published simulation algorithms have not shown
improvement over PHREEQ-C representations.
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Results – Two Phase System
Relative Permeability Interpolant Sensitivities
Equivalent Fraction: The earliest oil recovery obtained when using K Equivalent fraction as
interpolant can be explained with the behaviour depicted in the effluent concentration which
translates in a very rapid attachment and detachment of K ions onto and from the rock
compared with other ions. This behaviour reaches very fast the extreme of the interpolant
function switching quickly to low salinity relative pemeabilities. This observation is part of
the sensitivity analysis and do not constitute an optimization procedure.
When it comes to model two phase flow, literature (Dang et al., 2013) on the other hand
suggest the use of Calcium EQVFRIEX as interpolant based on experimental observations for
two phase flow.
Because the MIE mechanism states that monovalent and/or multivalent cations will exchange
with divalent cations bonded to oil molecules and the clay surface (Lager al, et., 2006), the
modelled mechanism should use either Ca or Mg equivalent fraction as interpolant. However,
this should be confirmed by experimental coreflooding before upscaling and forecasting
improve in oil recovery by LSW.
The results are presented in two different scales to observe the total injected pore volume
needed to see the total LSW effect reaching new equilibrium conditions. However, in a more
realistic scenario only few pore volumes will be injected if water of low salinity is available
due to economical reasons.
Aqueous Concentration: The aqueous concentration on the other hand produced very similar
results in the range 0-2 PV due to the rapid fall in the ion concentration toward the injected
values. Even though the ion concentrations are used to depict ion exchange in a single phase
system, when used as interpolant parameters the variation in its values are independent from
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the other ions (i.e. not a fraction) which switches the curves to the low salinity side very
quickly.
CEC Sensitivities: By analysing the CEC capacity behaviour identified in a single phase
system, it is possible to infer the reason why the recovery is speeded up in comparison with its
initial value as the changes in the equivalent fraction of the divalent ions are brought forward
which swaps the relative permeability curves.
The results obtained by using the model proposed by Dang (Dang et. al., 2012) using Fjelde
experimental observations (Fjelde et. al., 2012) confirm this behaviour in a system with
calcite dissolution and ion exchange but in a much smaller magnitude as shown in Figure 18.
However, as confirmed by observations (Tang and Morrow et al., 1999; Sorbie et. Al., 2010;
Zheng at al. 2014), the CEC defines the amount at exchange sites on a rock which are a
fundamental part of the MIE mechanism. So far in the published literature a threshold value
which defines the minimum CEC needed to produce the LSWE has not been identified and
this correlation has not been observed experimentally and further analysis is required.
In addition, as documented by Basin and Labrid (Basin and Labrid et al., 1991) high CEC
values are related with potential damage during the injection of a low divalent cation
concentration brine compared with the formation brine where K-X is replaced by sodium and
divalent cations over a 10 PV range being determinant in smectite stability and consequently
permeability decrease.
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Capillary pressure sensitivities
The capillary pressure sensitivities bring a new consideration in terms of modelling as the
published workflows to capture the LSWE do not mention and/or take into account capillary
pressure effects.
The first results show that when capillary pressure is used, water breakthrough is observed a
bit earlier but the oil recovery is faster. This behaviour is similar for all the equivalent
fractions except for K, where the water breakthrough is earlier and the recovery factor is
delayed in comparison with the zero capillary pressure case, Figure 19 and 20.
The early water breakthrough is explained due to the diffuse front caused when capillary
pressure is applied in the system in the short injected pore volume range, 0-2 PV. By contrast,
the faster recovery (i.e. after 2PV) is caused due to the more exchange sites available as water
diffuses in the system which alters the equivalent fraction of the interpolants. The equivalent
fraction of K on the other hand, produces much less recovery compared with its base case as
the available exchange sites are reduced and taken by other ions.
The second sensitivities using Ca and Mg equivalent fractions as interpolants with synthetic
capillary pressure curves confirms the previous observations where a faster water break
through is observed. In addition, this case states that for higher capillary pressure at the same
saturation the earlier the water breakthrough. However, this has not been documented in LSW
experiments.
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Injection brine optimization
The results obtained by decreasing the ion concentration of Na, Ca, Mg, and K as individual
scenarios with their respective equivalent fractions as relative permeability as interpolants
showed that a decrease in Mg concentration produces the earliest recovery followed by Ca.
This coincides with the observations documented by Lager (Lager et al., 2006) where a low
divalent cation concentration is recommended in the injection brine for the MIE process to be
more efficient. A decrease in Na does not produce any change with respect to its base case
due to its higher concentration. By contrast, a decrease in the K concentration reduces
drastically the LSWE compared with its base case as this reduces the Ion – Exchange process
of K as observed by Sabyrgali (Sabyrgali et al., 2012).
On the other hand, the result obtained by diluting the formation brine 50 and 100 times did
not improve the oil recovery mainly due to the small amounts of Sodium ions which are
needed to replace and detach the oil bonded molecules to divalent cations (Lager et. al.,
2006). This behaviour was observed with all the cations equivalent fractions in the range 0-2
PV, except when K – Equivalent Fraction is used as interpolant. In this case, in the range of 0-
2 PV, the use of the K-Equivalent Fraction as interpolant gives earlier and higher recoveries
compared to the base case. However, after 2 injected pore volumes, there is a decrease in
recovery explained by a decrease in the slope of K exchange.
LSW in Tertiary Mode
The results obtained during LSW in tertiary mode confirm the secondary mode LSW results
where K produced the earliest recovery. This response is again ascribed to the preference of
the rock for K compared with other ions.
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This results show the high degree of variation in recovery even when the system is in residual
oil saturation and show the pore volumes needed to see a complete change from HS – LS
conditions.
CONCLUSIONS
The Ion- Exchange Model implemented in GEM can reproduce the experimental observations
performed at Heriot-Watt University by representing the MIE mechanism of LSW in a single
phase system.
The CEC and the selectivity coefficients were used to match the experimental data which
have different effects on the Ion-Exchange process.
A general scaling factor to modify the CEC of the rock is presented as well as the parameters
that do not interfere in the Ion-Exchange process at core and field scale in a 1D system.
A general dependence of the rock CEC against oil recovery was found supported by a
published simulation model based on experimental data.
The sensitivities on the equivalent fraction of different ions as interpolants result in important
ranges of recovery with different amounts of PV needed to reach new equilibrium conditions.
This suggests that before it is possible to make predictions with a LS model, laboratory tests
are needed to calibrate the simulation outcomes.
Economical considerations are vital when deciding to implement a LSW as many pore
volumes may be needed before observing a successful EOR mechanism which is supported
with the reported results.
The brine optimization process performed in the current report agrees with experimental
observations and requirements for LSWE.
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SUGGESTION FOR FURTHER WORK
Several LSW publications are available which can be used as general QC of LSW modelling
at core scale to understand and capture the final effect on oil recovery before applying the
process at field scale.
An important suggestion for further work would be the inclusion of mineral reactions together
with the Ion-Exchange model in order to identify the sustained behaviour of the K
concentration in the effluent which was not matched with the current approach.
Even though MIE is reported in many experimental observations, it is mentioned to be a
secondary mechanism which comes after several injected pore volumes (Nasralla et al., 2014).
A suggestion would be to reproduce those observations using the current simulation tools and
assess numerically the extent to which the MIE mechanism is involved in the increase of
recovery factor.
The inclusion of minerals such as Kaolinite which is present in most of the reported
observations is highly recommended as well as the analysis of additional variables such as
pH, which can locally contribute to an increase in oil recovery at core scale.
The experimental results documented by Fjelde (Fjelde al, et., 2012) and reproduced by Dang
(Dang al, at., 2013) can be used to perform sensitivities on the mineral content, CEC, pH to
support empirical correlations.
Analyse the effect of physical dispersion in the results as this could lead to a reduction in the
expected recovery factor which could be important at field scale (Secombe al, et., 2006).
The use of PHREEQ-C as an additional tool to capture the exchange of ions and the mineral
reactions occurring in the rock has shown interesting results as the software is an important
reference when it comes to represent laboratory data. The inclusion of the PHREEQ-C code in
open code standard reservoir simulators could lead to an important advance in terms of EOR
modelling as reported in literature (Korrani et al., 2013, Korrani et al., 2014)
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REFERENCES
Amarson, T. and Keil, R.G. 2000 Mechanism of Pore Water Organic Matter Adsorption to Montmorillonite. Marine Chemistry, Vol. 71: p.309-320, Appelo, C.J. 1994 Cation and proton exchange, pH variations and carbonate reactions in a freshening aquifer. Water resources research, 1994. 36(10): p. 2793-2805. Austad, T., RezaeiDoust. A. and Puntervold, T., 2010 Chemical Mechanism of Low Salinity Water Flooding in Sandstone Reservoirs. In: SPE 129767 (Society of Petroleum Engineers), SPE Improved Oil Recovery Symposium, Tulsa, Oklahoma, USA 24-28 April 2010.
Bazin, B,. Labrid, J. 1991 Ion exchange and dissolution/precipitation modeling: application to the injection of aqueous fluids into a reservoir sandstone. SPE production engineering, p. 233-238. Bernard, G.G., 1967. Effect of Floodwater Salinity on Recovery of Oil from Cores Containing Clays. In: SPE 1725 (Society of Petroleum Engineers of AIME), 38th Annual California Regional Meeting of the Society of Petroleum Engineers of AIME, Los Angeles, California, 26-27 October 1967. De Bruin W. J. 2012 Simulation of Geochemical Processes during Low Salinity Water Flooding by Coupling Multiphase Buckley-Leverett Flow to the Geochemical Package PHREEQC. [Online] MSc Thesis, TUDelft. Available from: http://repository.tudelft.nl/view/ir/uuid%3A2d568014-8acb-4e8e-9d39-91c76f499a46/ [Accessed: 16 August 2014] Computer Modelling Group Ltd.: GEM user’s guide, Version 2013.1
Dang, C.T.Q., Nghiem,L.X., Chen,Z.,Nguyen,Q.P., 2013 Modeling Low Salinity Waterflooding: Ion Exchange, Geochemistry and Wettability Alteration. Paper 166447 presented at the SPE Annual Technical Conference and Exhibition. New Orleans, Louisiana, 30 September–2 October. Fjelde, I., Asen, S.V., Omekeh, A. 2012. Low Salinity Water Flooding Experiments and Interpretation by Simulations. Paper SPE 154142 presented at the Eighteenth SPE Improved Oil Recovery Symposium, Tulsa, OK, USA, April 14-18.
Grahame. D. 1947 Electrical double layer and theory of electro-capillarity. Chemical Reviews 41:pp. 441 -501.
Israelachvili, J., 1991 Intermolecular and surface forces. 2nd edition. Academic Press, San Diego C.A.
Jadhunandan, P.P., Morrow, N.R. 1995 Effect of Wettability on Waterflood Recovery for Crude-Oil/Brine/Rock Systems. SPE Reservoir Engineering, 10(1):40-46.
54
Jadhunandan, P. 1990 Effects of brine composition, crude oil and aging conditions on wettability and oil recovery. PhD dissertation. Jadhunandan, P. and N.R. 1991 Morrow, Spontaneous imbibition of water by crude oil/brine/rock systems. In Situ, 1991. 15(4): p. 319-345. Javaldel, I., Douhty, C. and C.F. Tsang. 1984 Groundwater Transport Handbook of Mathematical Models, American Geophysical Union, Water Resources Monograph 10, Washington, D.C.
Kazemi Nia Korrani, A., Jerauld, G. R., & Sepehrnoori, K. 2014 Coupled Geochemical-Based Modeling of Low Salinity Waterflooding. Society of Petroleum Engineers. doi:10.2118/169115-MS
Kazemi Nia Korrani, A., Sepehrnoori, K., & Delshad, M. 2013 A Novel Mechanistic Approach for Modeling Low Salinity Water Injection. Society of Petroleum Engineers. doi:10.2118/166523-MS
Kharaka, Y.K., Gunter, W.D., Aggarwal, P.K., Perkins, E.H., DeBraal, J.D. 1988 A Computer Program for Geochemical Modeling of Water-Rock Interactions. US Geological Survey, Water Resources Investigation Report 88-4227, Menlo Park, CA.
Kozaki, C. 2012 Efficiency of low salinity polymer flooding in sandstone cores. Online .University of Texas. Available from: http://hdl.handle.net/2152/ETD-UT-2012-05-4974 [Accessed: 16 August 2014]
Lager, A., Webb, K.J., Black, C.J.J. 2007 Impact of Brine Chemistry on Oil Recovery. Paper A24 presented at the 14th EAGE Symposium on Improved Oil Recovery, Cairo, 22-24 April.
Lager, A., Webb, K.J., Black, C.J.J., Singleton, M., Sorbie, K.S. 2006 Low-Salinity Oil Recovery – An Experimental Investigation. Paper SCA 2006-36 presented at the International Symposium of the Society of Core Analysts, Trondheim, Norway, 12-16 September.
Lager, A., Webb, K.J., Collins, I.R., Richmond, D.M. 2008b. LoSalTM Enhanced Oil Recovery: Evidence of Enhanced Oil Recovery at the Reservoir Scale. Paper SPE 113976 presented at the SPE/DOE Improved Oil Recovery Symposium, Tulsa, 19-23 April.
Lager, A., Webb, K.J., Black, C.J.J., Singleton, M. and Sorbie, K.S., 2008. Low Salinity Oil Recovery – An Experimental Investigation. Petrophysics, vol. 49, no. 1, p. 28-35. Lager, A., Webb, K.J., & Seccombe, J. 2011 Low Salinity Waterflood, Endicott, Alaska: Geochemical Study & Field Evidence of Multicomponent Ion Exchange. In IOR 2011. Ligthelm, D. et al., 2009. Novel waterflooding strategy by manipulation of injection brine composition. SPE 119835. Mahadevan, J., Lake, L.W., Johns, R. T., 2003 Estimation of the True Dispersivity in Field Scale Permeable Media, SPE 86303.
55
McGuire, P.L., Chatham, J.R., Paskvan, F.K., Sommer, D.M. and Carini, F.H., 2005 Low Salinity Oil Recovery: An Exciting New EOR Opportunity for Alaska’s North Slope. In: SPE 93903 (Society of Petroleum Engineers), SPE Western Regional Meeting, Irvine, CA, USA 30 March – 1 April 2005.
Mian, M. A., & Hilchie, D. W. 1981 Comparison Of Results From Three Cation Exchange Capacity Analysis Techniques. Society of Petroleum Engineers.
Morrow, N.R., Tang, G.Q., Valat, M., Xie, X. 1998 Prospects of Improved Oil Recovery Related to Wettability and Brine Composition. Journal of Petroleum and Engineering, 20(3-4):267-276.
Morrow, N. and Buckley, J., 2011 Improved Oil Recovery by Low-Salinity Waterflooding. Distinguished Author Series.
Nasralla, A., Bataweel, A. & Hisham, A., 2011 Investigation of wettability alteration by low-salinity water in sandstone rock. SPE 146322.
Nghiem, L.X., Shrivastava, V., Kohse, B. 2011 Modeling Aqueous Phase Behavior and Chemical Reactions in Compositional Simulation. Paper SPE 141417 SPE Reservoir Simulation Symposium, The Woodlands, TX, USA, February 21-23.
Omekeh A., Friis H.A., Fjelde I., Evje S. 2011 Experimental and Modelling Investigation of Ion Exchange during Low Salinity Waterflooding. Society of Core Analysts. Paper SCA2011-38.
Omekeh, A. V., Friis, H. A., Fjelde, I., & Evje, S. 2012 Modelling of Ion-Exchange and Solubility in Low Salinity Water Flooding. Society of Petroleum Engineers. doi:10.2118/154144-MS
Pope, G.A., L.W. Lake, and F.G. Helfferich. 1978 Cation Exchange in Chemical Flooding: part 1 - Basic Theory without Dispersion. SPE 6771: p. 418-434.
Ramez A. Nasralla, SPE, Hisham A. Nasr-El-Din. 2011 Impact of Electrical Surface Charges and Cation Exchange on Oil Recovery by Low Salinity Water. SPE 147937. SPE Asia Pacific Oil and Gas Conference and Exhibition held in Jakarta, Indonesia, 20-22 September 2011.
Ramez, A. Nasralla and Hisham, A. Nasr-El-Din, 2014. Double-Layer Expansion: Is it A Primary Mechanism of Improved Oil Recovery by Low-Salinity Waterflooding?. In: SPE 154334 (Society of Petroleum Engineers), Eighteenth SPE Improved Oil Recovery Symposium, Tulsa, Oklahoma, USA April 2013.
Ramirez, M, O. 1990. Cation Exchange Capacity Data Derived from Well Logs. SPE 21097. SPE Latin American Petroleum Engineering Conference at Rio de Janeiro, October 14-19.
Rivet, S.M. 2009. Coreflooding Oil Displacements with Low Salinity Brine. Master Thesis, University of Texas at Austin.
56
Salter, S. J. and Mohanty, K. K. 1982 Multiphase flow in porous media: Macroscopic Observations and Modeling, SPE 11017 presented at the 57th Annual Fall Technical Conf. of the SOE, New Orleands L.A. Sept 26-29.
Seccombe, J., Lager, A., Jerauld, G.R., Jhavier, B., Buikema, T., Bassler, S., Denis, J., Webb, K., Cockin, A., Fueg, E. 2010. Demonstration of Low Salinity EOR at Interwell Scale, Endicott Field, Alaska. Paper SPE 129692 presented at SPE/DOE Improved Oil Recovery Symposium, Tulsa, 24-28 April.
Sabyrgali, Y. 2012 Capabilities of simulators to model mechanisms of Low Salinity Waterflooding. MSc Thesis at Heriot Watt University.
Skrettingland, K., Holt, T., Tweheyo, M.T., Skjevrak. 2010. Snorre Low Salinity Water Injection – Core Flooding Experiments and Single Well Field Pilot. Paper SPE 129877 presented at the SPE Improved Oil Recovery Symposium, Tulsa, OK, USA, 24-28 April.
Sorbie K.S, SPE; Heriot-Watt University and I.R.Collins, BP Exploration. 2010 A Proposed Pore-Scale Mechanism for How Low Salinity Waterflooding Works. SPE 129833. SPE Improved Oil Recovery Symposium held in Tulsa, Oklahoma,USA, 24-28 April 2010.
Sheng, J. J., Critical review of low-salinity waterflooding. J. Petrol. Sci. Eng. (2014), http://dx.doi.org/10.1016/j. petrol.2014.05.026i
Tang, G.Q., & Morrow, N.R. 1997 Salinity, Temperature, Oil Composition and Oil Recovery by Waterflooding. SPE Reservoir Engineering, 12(4):269-276.
Tang, G. Q. & Morrow, N. R., 1999. Influence of brine composition and fine migration on crude oil/brine/rock interactions and oil recovery. Journal of Petroleum Science and Engineering, Volume 24, pp. 99-111. Webb, K. J., Black, C.J.J., Al-Ajeel. 2004. Low Salinity Oil Recovery – Log-Inject-Log. Paper SPE 89379 presented at the SPE/DOE Symposium on Improved Oil Recovery, Tulsa, 17-21 April. Webb, K. J., Black, C.J.J., Edmonds, I.J. 2005. Low Salinity Oil Recovery: The Role of Reservoir Condition Corefloods. Paper C18 presented at the 13th EAGE Symposium on Improved Oil Recovery, Budapest, Hungary, 25-27 April. Webb, K. J., Lager, A., Black, C.J.J. 2008. Comparison of High/Low Salinity Water/Oil Relative Permeability. Presented at the International Symposium of the Society of Core Analysts, Abu Dhabi, UAE, 29 October – 2 November. Webb, K. J., C.J.J. Black, and H. Al-Jeel. 2003. Low salinity oil recovery - log inject log. SPE 89379. Webb, K.J., C.J.J. Black, and I.J. Edmonds. 2005 Low salinity oil recovery - the role of reservoir condition corefloods. in EAGE conference. 2005. Budapest, Hungary.
57
Wu Y., Bai B. 2009. Efficient Simulation for Low-Salinity Waterflooding in Porous and Fractured Reservoirs. SPE 118830. SPE Reservoir Simulation Symposium held in the Woodlands, Texas,USA, 2-4 February 2009. Wu, Forsyth, Jiang. 1996 A consistent approach for applying numerical boundary conditions for multiphase subsurface Flow, Journal of Contaminant Hydrology, 23, pp. 157-184. Yildiz, H.O., Morrow, N.R. 1996 Effect of Brine Composition on Recovery of Moutray Crude Oil by Waterflooding. Journal of Petroleum Science and Engineering, 14:159-168. Zhang, G., and Villegas, E. I. 2012 Geochemical Reactive Transport Modelling in Oil & Gas Industry Business Drives, Challenges and Solutions. Proceedings, though Symposium. Zhang, Y., Xie, X., Morrow, N.R. 2007. Waterflood Performance by Injection of Brine with Different Salinity for Reservoir Cores. Paper SPE 109849 presented at the SPE Annual Technical Conference and Exhibition, Anaheim, CA, USA, 11-14 November. Zhang, Y. and Morrow, N.R., 2006. Comparison of Secondary and Tertiary Recovery With Change in Injection Brine Composition for Crude Oil/ Sandstone Combinations. In: SPE 99757 (Society of Petroleum Engineers), SPE/DOE Symposium on Improved Oil Recovery, Tulsa, Oklahoma, USA 22-26 April 2006.