SPE Current address: The author is currently working with Shell Abu Dhabi,

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1 PE 7855 The Effect of Wettability on aturation Functions and Impact on Carbonate Reservrs in the Middle East hehadeh K. Masalmeh hell International Explation and Production Copyright 22, ociety of Petroleum Engineers Inc. This paper was prepared f presentation at the th Abu Dhabi International Petroleum Exhibition and Conference, 3-6 October 22. This paper was selected f presentation by an PE Program Committee following review of infmation contained in an abstract submitted by the auth(s). Contents of the paper, as presented, have not been reviewed by the ociety of Petroleum Engineers and are subject to crection by the auth(s). The material, as presented, does not necessarily reflect any position of the ociety of Petroleum Engineers, its officers, members. Papers presented at PE meetings are subject to publication review by Editial Committees of the ociety of Petroleum Engineers. Electronic reproduction, distribution, stage of any part of this paper f commercial purposes without the written consent of the ociety of Petroleum Engineers is prohibited. Permission to reproduce in print is restricted to an abstract of not me than 3 wds; illustrations may not be copied. The abstract must contain conspicuous acknowledgment of where and by whom the paper was presented. Write Librarian, PE, P.O. Box , Richardson, TX , U..A., fax Abstract Wettability is an imptant fact, which affects the flow behavi in l reservrs. It has a profound effect on the shape of relative permeability and capillary pressure curves and consequently on l displacement processes in pous media. This paper presents experimental measurements on ce samples where the effect of wettability is investigated on connate water, residual l, l and water permeability end pnts, relative permeability and capillary pressure curves. The paper summarizes the main findings of few years of data collection on several ces from different carbonate fields in the Middle East, and a comparison with clastic data is made when appropriate. The data shows very low connate water f most carbonate fields investigated in this study even f low permeability rocks, md. The residual l saturation after resting wettability was measured to be less than % f both carbonate and sandstone fields. F water-wet samples a residual l of around 3% is measured. A distinct difference was found in the dependence of residual l saturation on initial l saturation f water-wet and mixed-wet ces. F water-wet samples increased almost linearly with, however; f mixed-wet samples was found to be constant f a very wide range of values. F water-wet samples we often measured high l relative permeability end pnt, K ro ( wc )>., and it decreased Current address: The auth is currently wking with hell Abu Dhabi, hehahdeh.masalmeh@shelldub.simis.com as the wettability changed to mixed-wet l-wet. The water relative permeability end pnt is low f water-wet samples and increased f mixed-wet l-wet samples. As demonstrated in the field case discussed in this paper, the findings of this study have imptant implications f field development and hydrocarbon recovery. Introduction Wettability is a maj fact that affects fluid flow behavi in pous medium. It has a profound effect on the shape of relative permeability and capillary pressure curves and consequently on l displacement processes. The effect of wettability on fluid flow and electrical properties of pous medium has been extensively studied in the literature [-6]. The objective of this study is to assess the effect of wettability on: Capillary pressure Connate water Residual l saturation Residual l saturation dependence on initial l saturation Relative permeability end pnts Relative permeability curves The experimental data confirms the strong relationship between the drainage capillary pressure and permeability and shows that the fced imbibition capillary pressure is only weakly dependent on permeability. The data also shows that Leverett-J function applicability is limited f the carbonate reservrs studied due to the complex pe structure as compared to sandstone. The residual l f l-wet mixed-wet samples is found to be me than 5 saturation units lower than that of water-wet samples. It is also found that the relative permeability of the wetting phase is me curved than that of the non-wetting phase. This is due to the combined effect of trapping and rock/fluid interactions. Experimental Program In this study a number of experimental techniques have been used. The capillary pressure is measured using a combination

2 2 MAALMEH.K. PE 7855 of the multi-speed centrifuge and CAPRICI [7] Pc-probe [8] techniques. The relative permeability measurements are perfmed using a combination of steady state, single speed and multi-speed centrifuge. Residual l and connate water saturations are measured using both multi-speed and single speed centrifuge techniques. Refined l decane was used to study water-wet system while dead crude l was used to reste wettability and study the non-water-wet system. The centrifuge experiments have been perfmed at 6 o C and atmospheric pressure using dead crude l and synthetic brine. After drainage experiment the plugs have been aged in crude l at 7 o C and bars f four weeks. The CAPRICI/Pcprobe experiments have been perfmed at 7 o C and bar using dead crude l and synthetic brine. The data presented in this study is measured on me than plugs from different fields, see figure. The permeability ranged from. md to 4 md. The bulk of the measurements are done on samples of permeability - md. The relative permeability curves (k ro and k rw ), capillary pressure (P c ) and residual l saturation ( ) have been obtained by numerical interpretation of the raw experimental data using hell numerical reservr simulat (MoRe). This had imptant impact on getting the proper relative permeability curves as analytical interpretation does not take into account the capillary end effect and therefe give erroneous results. Initial l/residual l crelations have been measured on two sets of samples, carbonate and sandstone. Crude l was used in the experiments on carbonate samples and the plugs were aged at each initial l saturation to reste wettability. Decane was used in the experiments on sandstone in der to study a water-wet system. Experimental Results Drainage Capillary Pressure. Primary drainage capillary pressure curves measured on water-wet samples show a strong dependence on permeability as often observed. Figures 2-3 show drainage capillary pressure curves measured on samples from two different carbonate fields. The permeability ranges between.2 md and 4 md. As the permeability decreases the capillary entry pressure increases. The drainage entry pressure varies between.5 to 5.6 bars. F field the entry pressure increases with permeability almost linearly while f filed 2 there is one entry pressure f each permeability range. Drainage capillary pressure is used to initialize reservr static model, i.e., to determine saturation as a function of height above free water level (FWL) and to calculate TOIIP GIIP of hydrocarbon reservrs. ince usually a limited number of capillary pressure curves are available, different models have been developed to calculate an average capillary pressure curves which are crelated with posity and permeability. Leverett J-function is one of the most commonly used fmulations. Its applicability to carbonate reservrs needs further investigations. Leverett J-Function. Harrison and Jing [9], reviewed four of the most popular saturation-height methods employed in the l and gas industry. It is beyond the scope of this paper to discuss those methods, in this section the focus will be on Leverett J-function which is given in eq.. J ( ) = Pc σ cosθ K ϕ () The J-function was iginally proposed to convert all capillary pressure data f clean sands to a universal curve. However, this fmulation is often used f shaly sand and f carbonates. Carbonate reservrs are known f their complex pe geometry which may indicate that such simple fmulation may not be applicable. This is indeed what the data shown in figures 4-5 demonstrates. Converting the drainage capillary pressure data into J-Function did not produce a single curve, the spread in the J-function is as large as in the individual P c curves shown in figure 2. Therefe, using J-function to calculate P c curves and saturation height functions may lead to serious errs in calculating hydrocarbon in place. The data shown in figure 2 is now being used to develop a new fmulation to crelate the capillary pressure with permeability of the carbonate samples. Imbibition Capillary Pressure. The imbibition capillary pressure was measured f some of the samples shown in figure 2. The measurements were perfmed after resting wettability by aging the ce samples f four weeks. The data shows a general trend of increasing the negative capillary entry pressure as the permeability decreases, see figure 6. The data does not show a strong crelation with permeability as is the case with drainage capillary pressure. The imbibition Pc plateau value increases from -.2 to -.4 bar as the permeability decreases from 3 to md. As wettability changes from strongly water-wet to either week water-wet, mixed-wet l-wet the dependence of entry pressure on permeability becomes weak. The difference between the primary drainage and imbibition capillary pressure curves can be best illustrated by comparing the P c curves of two samples from figures 2 and 6, e.g., samples of permeability.3 and 5.8 md, respectively. While the primary drainage P c plateau value of the first sample is a fact 3 higher than that of the second, their primary imbibition P c plateau value is almost the same. The data shown in figure 6 is measured using plugs of low permeability, measurements of imbibition P c on plugs in a wider range of permeability (. to 4 md) is ongng. Connate Water. Connate water saturation was measured in the centrifuge befe and after aging i.e., during primary drainage and secondary drainage. Table shows that the connate water after aging is always higher than that befe aging (when aging introduces wettability changes). The increase in connate water in the secondary drainage is due to the extra trapping as now water is not anyme the wetting

3 PE 7855 THE EFFECT OF WETTABILITY ON ATURATION FUNCTION 3 phase and droplets of water can be trapped in the middle of the large pes []. An increase of 5 saturation units in connate water is sometimes observed. The increase in connate water during the secondary drainage does not mean l-wet nonwater-wet reservrs will have higher initial water saturation as compared to water-wet reservrs. The connate water saturation measured in primary drainage is me representative as primary drainage is the process which took place during l migration regardless of the current wettability status of the reservrs. In some cases this assumption may not be valid, however; this discussion is beyond the scope of this paper. The connate water saturation measured during primary drainage f most of the carbonate plugs used in the study is very low, averaging 5-% even f plugs of permeability of -5 md. andstone data showed usually higher connate water, mainly in the range of 5-25%. In both cases connate water was measured after cleaning the plugs to waterwet conditions. Residual Oil aturation. Residual l saturation was measured befe and after resting wettability on carbonate samples. The water-wet samples showed an of 2-3%. After aging the plugs, residual l saturation was measured to be between 5-%. This low value of residual l saturation can only be obtained using either the centrifuge technique long ce gravity drainage experiments. Flooding experiments usually end up with high remaining l saturation as usually the experiments stop after flooding with few pe volumes of water. Welge s integration of the Buckley-Leverett equations shows that many pe volumes of throughput will be required to reduce the l saturation close to in mixed-wet systems [-2]. Although low pe volumes are injected in the reservr, surface film drainage may act to reduce the effective remaining l saturation. In mixed-wet reservrs l behind the flood front segregates upward due to density difference, accumulating at the top of the reservr. Given enough time the l will drain to values close to residual l saturation. Residual Oil aturation Dependence on Initial Oil aturation. The / data measured in this study is shown figures 7 and 8 f the water-wet and mixed-wet cases, respectively. The water-wet data is measured on sandstone samples with permeability ranges between.-3 md. The mixed-wet data is measured on carbonate samples with permeability ranges between -8 md. The figures show clear difference between the data of both cases. The following can clearly be observed when comparing both cases: - F the water-wet case, there is a clear trend in the data where increases almost linearly with. The imum is 3%, which agrees with the high residual l saturation expected f water-wet cases. 2- There is no clear / crelation f the mixed-wet case. With the exception of few pnts the residual l saturation is less than 7% even f 9% initial l saturation. 3- The data of both water-wet and mixed-wet cases shows that / crelation is independent of the rock permeability (in the permeability range investigated) and rock facies. 4- In both cases the data does not agree with the widely used Land crelation [3], Land crelation seems to overestimate residual l saturation especially f low. The fact that after resting wettability the residual l is independent of initial l saturation, f such a wide range of, stands as a surprising result. This is not expected to be a general case, however we expect a weak dependence of on f non-water-wet cases. This can be explained by understanding the effect of wettability on residual l saturation. F water-wet rock, l is trapped as disconnected blobs in the center of the big pes. Thus, the me pes invaded in the drainage experiment the me l is gng to be trapped. F an l-wet ce sample, in principle l can not be trapped and residual l saturation is zero as l can always find a continuous route to escape. F mixed-wet pous medium l can be trapped in the water-wet part only. In this case as initial l saturation increases there is me chance f l to be trapped and residual saturation increases. But at the same time the plug becomes less water-wet ( me l-wet) which decreases residual l saturation. Therefe, increasing initial l saturation does not necessarily increase residual l saturation. Meover, in mixed-wet system where part of the pe is lwet and part is water-wet, l will always find a rout to escape. Oil can only be trapped at very high water saturation when some of the escape routes are completely disconnected. These are two different scenarios which may result in low residual l saturation and a residual l saturation which is hardly dependent on initial l saturation. The data presented in the two figures shows that / crelation can be modeled as: - F water-wet rock: * ( ) = (2) =.8 and = F mixed-wet rock: ( ( ) = ) = < ( 3a) (3b) where is the imum initial l saturation and is the imum residual l saturation. F the example studied in this wk =.9 and =.7. This is the same conclusion we found in [4].

4 4 MAALMEH.K. PE 7855 Relative Permeability End Pnt. The l relative permeability at connate water K ro ( wc ) and the brine relative permeability at residual l K rw ( ) have been measured f carbonate and sandstone plugs. F carbonate plugs K ro ( wc ) and K rw ( ) have been measured using both dead crude and mineral l while f sandstone decane/brine system was used. Figures 9-2 show both K ro ( wc ) and K rw ( ) f different sets of samples from different fields. The following can be observed from the figures: Figure 9 represents an extreme l-wet case where the l end pnt is very low (~.2) while the water end pnt is very high (~.8). After examining many data sets in the last four years, this is the only ce material that showed this characteristic. The l relative permeability measured using the same ce material showed very high Cey exponent (n o > 5) as expected f l-wet rock. Figure shows high l end pnt ~.6 and low water end pnt ~.2. One is tempted to characterize such crude/brine/rock system as water-wet. However, the imbibition capillary pressure curve measure on the same samples did not show water-wet behavi. Meover, when decane was used in the experiments a higher l end pnt was measured, K ro ( wc )~. It seems that the data shown in figure can still characterize mixed-wet system. The data in figure shows similar values f both water and l end pnt, around.4. The data characterizes another mixed-wet case. The data in figure 2 shows high l end pnt, the water end pnt is not available f this set of plugs. The l end pnt is measured using mineral l after cleaning the samples to water-wet conditions. In this case K ro ( wc ) is measured to be higher than, values up to.5 are no exception. This high l end pnt characterizes water-wet ces. The reason f such high end pnt may not be well understood but it is usually attributed to lubrication effect where the water film on the rock surface acts as a lubricant f l which increases the l end pnt to higher than. To complete the data set, the water end pnt was measured f some of the plugs shown in figures - using decane/water system. A value of.-.2 is obtained while the l end pnt was also measured to be. higher, similar to the data in figure 2. Oil and Water Relative Permeability. Water and l relative permeability curves have been measured on some of the samples shown in figures 9-2. Figure 3 shows typical water and l relative permeability curves f water-wet, mixed-wet and l-wet ces. The measured relative permeability curves show some variations and it is not appropriate to characterize, f example, mixed-wet plugs with one relative permeability curve. Meover, mixed-wetting can be used to describe plugs that have distinct difference in their wetting status where a different ption of their pe surface is l-wet while the rest is water-wet. F example, a plug where 3% of its pe surface is l-wet and 7% is water-wet vise versa will be described as mixed-wet. However, each case will have different relative permeability curve. Oil-wet can also describe systems of a wide range of contact angles, the same applies to water-wetness. The relative permeability curves shown in figure 3 are generated using Cey presentation, the parameters used to generate the curves are shown in table 2. The l-wet case is rather exceptional, this is the only ce material investigated which shows very low l relative permeability end pnt. Oilwet plugs may have higher relative permeability l end pnt, which consequently affects predicted l and water production. The relative permeability curves are shown on both linear and logarithmic scales. The linear scale highlights the difference between the relative permeability curves near the end pnts. The difference at low saturation becomes clear only when plotted on a logarithmic scale. As shown in the figure the relative permeability of the wetting phase is me curved than the non-wetting phase, i.e., it has higher Cey exponent. This shows that in an lwet rock, the water will flow me easily than the l during water flooding. On the other hand, in a water-wet rock the l will flow me easily than water. In a water-wet case, water will occupy the small pes and fm a thin film on the rock surface while l will occupy the centers of the large pes. During water flooding, l will flow on top of the water film and in the center of the large pes while water will be flowing on the surface of the rock. The l trapped in the center of the large pes will also hinder water flow. In l-wet rock the location of the two fluids is reversed as compared to water-wet case, which explains the trends shown in figure 3. Field Example The impact of the measured relative permeability (shown in figure 3) and capillary pressure curves on recovery efficiency has been quantified using an element model. The imbibition capillary pressure curves used f each case are shown in figure 4. The figure shows the P c curve of one of the layers in the model, each layer had its own P c depending on its posity and permeability. The model consists of 25 layers in the z- direction 5 m thick, 4 m wide (y-direction) and 6 m long (x-direction). The permeability and posity of the different layers is shown in figure 5. One vertical inject and one vertical producer are positioned in the opposite cners of the model. The simulated l and water production f the three different cases are shown in figure 6. The figure shows that the water-wet case has slower l production but better sweep. It has the latest water breakthrough, it just took place after 7 years of production. The mixed-wet case shows the fastest l production and the highest recovery. The l-wet case shows the lowest l recovery, even lower than expected, given the period of the water flooding and the distance between the inject and the producer. This low l production is due to the exceptionally low l relative permeability end pnt, see

5 PE 7855 THE EFFECT OF WETTABILITY ON ATURATION FUNCTION 5 figure 3 and table 2. We found that the trends shown in figure 6 are very sensitive to min variations in the relative permeability curves. F example, the water-wet case shows fastest l recovery and earliest water-breakthrough if the water relative permeability end pnt is increased to.2. Also increasing the l relative permeability end pnt of the l-wet case to.6, made significant improvement on l recovery. Therefe, some of the conclusions, which are usually found in literature, strongly depend on the exact shape of the relative permeability curves used f each wettability case. The model was run f 7 years, me l can still be recovered from mixed-wet and especially from the l-wet case if water flooding to continue in case the distance between wells is shtened. However, drilling me wells longer water flooding increases the cost of the field development. Therefe, while the ultimate recovery increases f l-wet case, it is not always economic to continue water flooding f a very long period. The extra l recovered needs to overcome the cost of longer water flooding extra wells to justify longer development. Conclusions everal conclusions can be drawn from the data presented in this paper: While there is a strong crelation between the drainage capillary pressure and permeability, the fced imbibition capillary pressure is only weakly dependent on permeability. Leverett-J function applicability is limited in carbonates due to the complex pe structure as compared to sandstone. The connate water in the secondary drainage is up to 5 saturation units higher than that in the primary drainage, when wettability is changed in between the cycles. This is due to trapping of water during the secondary drainage experiment. The residual l saturation f l-wet mixed-wet samples can be me than 5-2 saturation units lower than that of water-wet samples. There is hardly any dependence of on initial l saturation f the mixed-wet ce material used in this study, however; f water-wet ce samples is strongly dependent on. The data of both water-wet and mixed-wet cases shows that / crelation is independent of the rock permeability (in the permeability range investigated) and rock facies. The relative permeability of the wetting phase is me curved than that of the non-wetting phase. This is due to the combined effect of trapping and rock/fluid interaction. The l relative permeability at connate water K ro ( wc ) varied considerably depending on the wettability of the sample, e.g., K ro ( wc ) higher than f strongly water-wet samples and ~.2 f l-wet samples. The water relative permeability end pnt at residual l saturation K rw ( ) increased as l-wetness increased, K rw ( ) less than.2 f the water-wet samples and ~.8 f l-wet samples. The impact of the measured relative permeability curves and residual l saturation has been quantified using an element model. The simulated production is strongly dependent on the exact shape of the relative permeability curves. Min variation in the relative permeability curves changes the expected l and water production trends. Nomenclature k ro = l relative permeability K ro ( wc ) = l relative permeability end pnt k rw = water relative permeability K rw ( ) = water relative permeability end pnt n o = l Cey exponent n w = water Cey exponent P c = capillary pressure RO = remaining l saturation = initial l saturation = imum initial l saturation = residual l saturation = imum residual l saturation = connate water wc Acknowledgements The auth would like to thank hell Abu Dhabi management f permission to publish this paper. pecial thanks are due to Dr. Xudong Jing from hell Reseach f technical discussions and valuable comments on the manuscripts. References - Anderson, W.G.: Wettability Literature urvey-part 3: The Effect of Wettability on the Electrical Properties of Pous Media, JPT, Anderson, W.G.: Wettability Literature urvey-part 4: The Effect of Wettability on Capillary Pressure, JPT, Anderson W.G.: Wettability Literature urvey-part 5: The Effect of Wettability on Relative Permeability, JPT, Mrow, N.R., 99. Wettability and its Effects on Oil Recovery, PE Res. Eng. (99) 5, pp Ghang, Y.C., Mohanty, K.K., Huang, D.D., Honarpour M.M.: The Impact of Wettability and Ce-cale Heterogeneity on Relative Permeability, J. Pet. ci. Eng. (997) Masalmeh,.K.: The Effect of Wettability Heterogeneity on Capillary Pressure and Relative Permeability, paper presented at the 7th International ymposium on Evaluation of Reservr Wettability and its Effect on Oil Recovery, ocro, Tasmania, Australia, March 2-5, 22, submitted f publication in JPT. 7- Kokkedee, J.A., Boutkan, V.K.: Towards Measurement of Capillary Pressure and Relative Permeability at Representative Wettability, paper presented at European ymposium on Improved Oil Recovery, Moscow, van Wunnik, J.N.M, Oedai,., Masalmeh.K.: Capillary Pressure Probe f CAL Applications, presented at the symposium of pecial Ce Analysts CA-998, Golden, Colado, 999.

6 6 MAALMEH.K. PE Harrison, B., Jing, X.D.: aturation-height Methods and their Impact on Volumetric Hydrocarbon-In-Place Estimates, paper PE 7326 presented at the 2 PE Annual Technical Conference and Exhibition, New Orleans, ept. 3 to Oct Masalmeh,.K.: Experimental Measurements of Capillary Pressure and Relative Permeability Hysteresis presented at the ymposium of pecial Ce Analysts, Edinburgh, 2. - alathiel, R.A.: Oil Recovery by urface Film Drainage In Mixed-Wettability Rocks, oc. Pet. Enj. J., Oct Hirasaki, G.J.: Dependence of Waterflood Remaining Oil aturation on Relative Permeability, Capillary Pressure, and Reservr Parameters in Mixed Wet, Turbidite ands, paper PE 3763 presented at the PE Annual Technical Conference and Exhibition, Dallas, Oct , Land, C..: Calculation of Imbibition Relative Permeability f Two and Three Phase Flow From Rock Properties, PEJ (968) Masalmeh,.K.: High Oil Recoveries from Transition Zones, paper ADPE-922 presented at the 8th ADIPEC Annual Technical Conference and Exhibition, Abu Dhabi, Oct. 5-8, 2. Table : Comparing connate water in primary and secondary drainage experiments. c % md pd sd Permeability Table 2: Relative Permeability Parameters ystem wc K rw ( wc ) K ro ( ) n w n o Water-wet Mixed-wet Oil-wet

7 PE 7855 THE EFFECT OF WETTABILITY ON ATURATION FUNCTION 7. Field Field 2 Field 3 Field posity Pc (bar) K=.3 K=3.7 K=4.26 K=4.43 K=4.93 K=5.8 K=6.54 K=6.87 K=8.2 Figure : posity-permeability of some of the samples used in this study taken from 4 different fields, field 4 is sandstone. Figure 2: Drainage capillary pressure f samples from field, see figure Pc (bar) k=.2 k=.2 k=2.3 k=2.6 k=3.4 k=4.7 k=4.9 k=37 k=53 k=78 k=348 J() J_Function K=.3 K=3.7 K=4.26 K=4.43 K=4.93 K=5.8 K=6.54 K=6.87 K= Figure 3: Drainage capillary pressure f samples from field 2, see figure Figure 4: Leverett J-Function f samples from field, see figure. J() J_Function k=.2 k=.2 k=2.3 k=2.6 k=3.4 k=4.7 k=4.9 k=37 k=53 k=78 k=348.. Pc (bar) K=.3 K=3.7 K=4.26 K=5.8 K=5.2 K=8.2 K=3.7 Figure 5: Leverett J-Function f samples from field 2, see figure. Figure 6: Imbibition capillary pressure curves f samples from field, see figure.

8 8 MAALMEH.K. PE Figure 7: / crelation f water wet ces. Figure 8: / crelation f mixed wet ces...8 Kro( c) Krw ().8.6 Kro(sw c) Krw () Permeability (md) Figure 9: Oil and water end pnt f strongly l-wet ces. Figure : Oil and water end pnt f mixed-wet ces..8 Kro( c) Krw () 2. Kro(c) Figure : Oil and water end pnt f another mixedwet ces Figure 2: Oil end pnt f strongly water-wet ces.

9 PE 7855 THE EFFECT OF WETTABILITY ON ATURATION FUNCTION 9 kr.e+.e-.e-2.e-3 kro_m W.E-4 krw_m W kro_w W.E-5 krw_w W kro_o W.E-6 krw_o W.E-7 kr kro_mw krw _MW kro_ww krw _WW kro_ow krw _OW. Figure 3a: Oil and water relative permeability curves used in this study f different wettability cases, logarithmic scale. Figure 3b: Oil and water relative permeability curves used in this study f different wettability cases, linear scale. Pc (PI) 2 - water-wet mixed-wet l-wet -2.. Figure 4: Imbibition capillary pressure curves used in this study f different wettability cases posity (fraction) Figure 5: posity-permeability of the different layers of the model used in this study. Figure 6: Water and l production f the different wettability cases.