scholarly journals Applying low-salinity water to alter wettability in carbonate oil reservoirs: an experimental study

2020 ◽  
Author(s):  
Erfan Hosseini ◽  
Zhongwei Chen ◽  
Mohammad Sarmadivaleh ◽  
Dana Mohammadnazar
Keyword(s):  
Contact Angle ◽  
Relative Permeability ◽  
Carbonate Reservoir ◽  
Wettability Alteration ◽  
Formation Water ◽  
Low Salinity ◽  
Smart Water ◽  
Low Salinity Water ◽  
Salinity Water ◽  
The Impact

Abstract Seawater has been widely used as an injection fluid for maintaining pressure in sandstone and carbonate reservoirs. In the literature related to EOR research, it was noted that diluted seawater (low-salinity water) can highly improve recovery due to the specific ions (such as Ca2+, Mg2+, and SO42−). Such conclusions lead to the application of “Smart Water” in which changing the ion composition of injected water alters wettability and enhances recovery. Although many theories have been established to explain the mechanism of this phenomenon, almost all of them are limited to sandstone rocks, and the impact of smart water on carbonated reservoirs has rarely been explored. This study experimentally investigates the impact of the injection of high- and low-salinity and smart water on the change of wettability and recovery improvement in an Iranian South oil reservoir. Two different sets of experimental work were conducted. In the first set of experiments, the effect of formation water, diluted formation water (from 223,969 to 5000 ppm and 2000 ppm), seawater (initially 51,400 ppm), and diluted seawater on wettability alteration is investigated by monitoring the contact angle and relative permeability variation. The results showed that dilution of seawater to 2000 ppm has the most impact on wettability alteration. The relative permeability changed, and the contact angle decreased by a significant value of 100°, and recovery increased by about 71%. In the second set, the effect of ion change on the result was studied. For this purpose, the sulfate ion of diluted seawater (2000 ppm) is substituted by phosphate ion (H2PO4−). The results show the wettability alteration similar to the sulfate one. This study sheds light on the possible mechanism of wettability alteration in the carbonate reservoir, and the result will help to design a better low-salinity injection scenario.

Enhanced Oil Recovery using Smart Water Injection

2018 ◽  
Vol 24 (8) ◽  
pp. 40
Author(s):  
Hussain Ali Baker ◽  
Kareem A. Alwan ◽  
Saher Faris Fadhil
Keyword(s):  
Oil Recovery ◽  
Water Injection ◽  
Deionized Water ◽  
Water Flooding ◽  
Wettability Alteration ◽  
Formation Water ◽  
Low Salinity ◽  
Smart Water ◽  
Low Salinity Water ◽  
Salinity Water

Smart water flooding (low salinity water flooding) was mainly invested in a sandstone reservoir. The main reasons for using low salinity water flooding are; to improve oil recovery and to give a support for the reservoir pressure. In this study, two core plugs of sandstone were used with different permeability from south of Iraq to explain the effect of water injection with different ions concentration on the oil recovery. Water types that have been used are formation water, seawater, modified low salinity water, and deionized water. The effects of water salinity, the flow rate of water injected, and the permeability of core plugs have been studied in order to summarize the best conditions of low salinity water flooding. The result of this experimental work shows that the water without any free ions (deionized water) and modified low salinity water have improved better oil recovery than the formation water and seawater as a secondary oil process. The increase in oil recovery factor related to the wettability alteration during low salinity water flooding which causes a decrease in the interfacial tension between the crude oil in porous media and the surface of reservoir rocks. As well as the dissolution of minerals such as calcite Ca+2 was observed in this work, which causes an increase in the pH value. All these factors led to change the wettability of rock to be more water-wet, so the oil recovery can be increased.  

Impact of clay type and water composition on low salinity water injection – visualisation approach

2018 ◽  
Vol 58 (1) ◽  
pp. 51 ◽  
Author(s):  
Tammy Amirian ◽  
Manouchehr Haghighi
Keyword(s):  
Oil Recovery ◽  
Wettability Alteration ◽  
Oil Film ◽  
Low Salinity ◽  
Water Composition ◽  
Low Salinity Water ◽  
Monovalent Ions ◽  
Salinity Water ◽  
The Impact ◽  
Clay Type

Low salinity water (LSW) injection as an enhanced oil recovery method has attracted much attention in the past two decades. Previously, it was found that the presence of clay such as kaolinite and water composition like the nature of cations affect the enhancement of oil recovery under LSW injection. In this study, a pore-scale visualisation approach was developed using a 2D glass micromodel to investigate the impact of clay type and water composition on LSW injection. The glass micromodels were coated by kaolinite and illite. A meniscus moving mechanism was observed and the oil–water interface moved through narrow throats to large bodies, displacing the wetting phase (oil phase). In the presence of kaolinite, the effect of LSW injection was reflected in the change to the wettability with a transition towards water-wetness in the large sections of the pore walls. The advance of the stable water front left behind an oil film on the oil-wet portions of pore walls; however, in water-wet surfaces, the interface moved towards the surface and replaced the oil film. As a result of wettability alteration towards a water-wet state, the capillary forces were not dominant throughout the system and the water–oil menisci displaced oil in large portions of very narrow channels. This LSW effect was not observed in the presence of illite. With regard to the water composition effect, systems containing divalent cations like Ca2+ showed the same extent of recovery as those containing only monovalent ions. The observation indicates a significant role of cation exchange in wettability alteration. Fines migration was insignificant in the observations.

scholarly journals Sandstone Reservoir Wettability Alteration Due to Water Softening: Impact of Silica Nanoparticles on Sand Production Mechanism

2020 ◽  
Vol 10 (5) ◽  
pp. 6328-6342 ◽  
Keyword(s):  
Contact Angle ◽  
Silica Nanoparticles ◽  
Oil Recovery ◽  
Reservoir Rock ◽  
Wettability Alteration ◽  
Sand Production ◽  
Thin Sections ◽  
Low Salinity ◽  
Low Salinity Water ◽  
Salinity Water

Low salinity water in the oil reservoirs changes the wettability and increases the oil recovery factor. In sandstone reservoirs, the sand production occurs or intensifies with wettability alteration due to low salinity water injection. In any case, sand production should be stopped and there are many ways to prevent sand production. By modifying the composition of low salinity water, it can be adapted to be more compatible with the reservoir rock and formation water, which has the least formation damage. By eliminating magnesium and calcium ions, smart soft water (SSW) is created which is economically suitable for injection into the reservoirs. By stabilizing the nanoparticles in SSW, nanofluids can be prepared which with injection into the sandstones reservoir increase the oil recovery, change the wettability and increase the rock strength. In this present, SSW composition was determined by compatibility testing, and the SiO2 nanoparticle with 1000 ppm concentration was stabilized in SSW. Eight thin sections were oil wetted by using normal heptane solution and different molars of stearic acid and two thin sections were considered as base thin sections to compare the effect of wettability alteration on sand production. Thin sections were immersed in SSW and Nanofluid, the amount of contact angle and sand production were measured in both cases. The amount of sand produced and the contact angle in SSW was higher than the Nanofluid. The silica nanoparticles reduced the contact angle (more water wetting) and by sitting between the sand particles, more than 40%, it reduced sand production.

Extended Fractional-Flow Model of Low-Salinity Waterflooding Accounting for Dispersion and Effective Salinity Range

SPE Journal ◽  
2019 ◽  
Vol 24 (06) ◽  
pp. 2874-2888 ◽  
Author(s):  
Hasan Al–Ibadi ◽  
Karl D. Stephen ◽  
Eric J. Mackay
Keyword(s):  
Relative Permeability ◽  
Flow Behavior ◽  
Flow Analysis ◽  
Salinity Range ◽  
Fractional Flow ◽  
Low Salinity ◽  
Low Salinity Water ◽  
Low Salinity Waterflooding ◽  
Salinity Water ◽  
The Impact

Summary Low–salinity waterflooding (LSWF) is an emergent technology developed to increase oil recovery. Laboratory–scale testing of this process is common, but modeling at the production scale is less well–reported. Various descriptions of the functional relationship between salinity and relative permeability have been presented in the literature, with respect to the differences in the effective salinity range over which the mechanisms occur. In this paper, we focus on these properties and their impact on fractional flow of LSWF at the reservoir scale. We present numerical observations that characterize flow behavior accounting for dispersion. We analyzed linear and nonlinear functions relating salinity to relative permeability and various effective salinity ranges using a numerical simulator. We analyzed the effect of numerical and physical dispersion of salinity on the velocity of the waterflood fronts as an expansion of fractional–flow theory, which normally assumes shock–like behavior of water and concentration fronts. We observed that dispersion of the salinity profile affects the fractional–flow behavior depending on the effective salinity range. The simulator solution is equal to analytical predictions from fractional–flow analysis when the midpoint of the effective salinity range lies between the formation and injected salinities. However, retardation behavior similar to the effect of adsorption occurs when these midpoint concentrations are not coincidental. This alters the velocities of high– and low–salinity water fronts. We derived an extended form of the fractional–flow analysis to include the impact of salinity dispersion. A new factor quantifies a physical or numerical retardation that occurs. We can now modify the effects that dispersion has on the breakthrough times of high– and low–salinity water fronts during LSWF. This improves predictive ability and also reduces the requirement for full simulation.

scholarly journals Experimental investigation of water composition and salinity effect on the oil recovery in carbonate reservoirs

2020 ◽  
Vol 75 ◽  
pp. 21
Author(s):  
Seyyed Hayan Zaheri ◽  
Hossein Khalili ◽  
Mohammad Sharifi
Keyword(s):  
Oil Recovery ◽  
Calcium Ions ◽  
Water Injection ◽  
Wettability Alteration ◽  
Fluid Composition ◽  
Formation Water ◽  
Low Salinity ◽  
Low Salinity Water ◽  
Different Types ◽  
Salinity Water

Water injection has been known as a conventional approach employed for years in order to achieve higher oil recovery from oil reservoirs. Since the last decade many researchers conducted on the water injection assessment suggested that low salinity water flooding can be an effective flooding mechanism and it can be used as an enhanced oil recovery method. Several examinations were conducted to identify governing mechanisms entailed in oil extraction and the effect of salinity and different types of ionic contents contained in Formation Water (FW) and injected fluid. This study is dedicated to address the influence of salinity and different types of ionic contents contained in formation water and injected fluid on incremental oil recovery. For this purpose, fluid–fluid and rock–fluid interaction were investigated especially for evaluating the effect of calcium ions in the formation water and sulfate ions in the injected water. Several experiments were carried out including core-flooding, contact angle, and imbibition tests. While former researchers concluded that reducing the salinity of injected water causing a decrease in ionic strength may lead to a greater oil recovery, in this research, we showed that these statements are not necessarily true. It was observed that existence of the high calcium concentration in the formation water would cause significant effect on wettability status of rocks and final oil recovery during low salinity water injection. This process is mainly due to rock wettability alteration. Wettability alteration mechanism in carbonate rocks is explained through interaction between rock and fluid composition. The results indicate the decisive role of calcium ions in the formation water at all stages from aging in oil to primary and secondary recovery. In addition to that, it was observed that more sulfate ion concentration in the injected water enhances rock wettability alteration.

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