EOR by Smart Water Flooding in Sandstone Reservoirs - Effect of Sandstone Mineralogy on Initial Wetting and Oil Recovery

Author(s):  
Aleksandr Mamonov ◽  
Tina Puntervold ◽  
Skule Strand
2017 ◽  
Vol 139 (6) ◽  
Author(s):  
Malek Jalilian ◽  
Peyman Pourafshary ◽  
Behnam Sedaee Sola ◽  
Mosayyeb Kamari

Designing smart water (SW) by optimizing the chemical composition of injected brine is a promising low-cost technique that has been developed for both sandstone and carbonate reservoirs for several decades. In this study, the impact of SW flooding during tertiary oil recovery phase was investigated by core flooding analysis of pure limestone carbonate rocks. Increasing the sulfate ion concentration by using CaSO4 and MgSO4 of NaCl concentration and finally reducing the total salinity were the main manipulations performed to optimize SW. The main objective of this research is to compare active cations including Ca2+ and Mg2+ in the presence of sulfate ions (SO42−) with regard to their efficiency in the enhancement of oil production during SW flooding of carbonate cores. The results revealed a 14.5% increase in the recovery factor by CaSO4 proving its greater effectiveness compared to MgSO4, which led to an 11.5% production enhancement. It was also realized that low-salinity water flooding (LSWF) did not lead to a significant positive effect as it contributed less than 2% in the tertiary stage.


2020 ◽  
Vol 10 (6) ◽  
pp. 6652-6668

Historically, smart water flooding is proved as one of the methods used to enhance oil recovery from hydrocarbon reservoirs. This method has been spread due to its low cost and ease of operation, with changing the composition and concentration of salts in the water, the smart water injection leads to more excellent compatibility with rock and fluids. However, due to a large number of sandstone reservoirs in the world and the increase of the recovery factor using this high-efficiency method, a problem occurs with the continued injection of smart water into these reservoirs a phenomenon happened in which called rock leaching. Indeed, sand production is the most common problem in these fields. Rock wettability alteration toward water wetting is considered as the main cause of sand production during the smart water injection mechanism. During this process, due to stresses on the rock surface as well as disturbance of equilibrium, the sand production in the porous media takes place. In this paper, the effect of wettability alteration of oil wetted sandstones (0.005,0.01,0.02 and 0.03 molar stearic acid in normal heptane) on sand production in the presence of smart water is fully investigated. The implementation of an effective chemical method, which is nanoparticles, have been executed to prevent sand production. By stabilizing silica nanoparticles (SiO2) at an optimum concentration of 2000 ppm in smart water (pH=8) according to the results of Zeta potential and DLS test, the effect of wettability alteration of oil wetted sandstones on sand production in the presence of smart water with nanoparticles is thoroughly reviewed. Ultimately, a comparison of the results showed that nanoparticles significantly reduced sand production.


Researchers have proved the significance of water injection by tuning its composition and salinity into the reservoir during smart water flooding. Once the smart water invades through the pore spaces, it destabilises crude oil-brine-rock (COBR) that leads to change in wettability of the reservoir rocks. During hydrocarbon accumulation and migration, polar organic compounds were being adsorbed on the rock surface making the reservoir oil/mixed wet in nature. Upon invasion of smart water, due to detachment of polar compounds from the rock surfaces, the wettability changes from oil/mixed wet to water wet thus enhances the oil recovery efficiency. The objective of this paper is to find optimum salinity and ionic composition of the synthetic brines at which maximum oil recovery would be observed. Three core flood studies have been conducted in the laboratory to investigate the effect of pH, composition and salinity of the injected brine over oil recovery. Every time, flooding has been conducted at reservoir formation brine salinity i.e at 1400 ppm followed by different salinities. Here, tertiary mode of flooding has been carried out for two core samples while secondary flooding for one. Results showed maximum oil recovery by 40.12% of original oil in place (OOIP) at 1050ppm brine salinity at secondary mode of flooding. So, optimized smart water has been proposed with 03 major salts, KCl, MgCl2 and CaCl2 in secondary mode of flooding that showed maximum oil recovery in terms of original oil in place.


2020 ◽  
Vol 17 (5) ◽  
pp. 1318-1328
Author(s):  
Sara Habibi ◽  
Arezou Jafari ◽  
Zahra Fakhroueian

Abstract Smart water flooding, as a popular method to change the wettability of carbonate rocks, is one of the interesting and challenging issues in reservoir engineering. In addition, the recent studies show that nanoparticles have a great potential for application in EOR processes. However, little research has been conducted on the use of smart water with nanoparticles in enhanced oil recovery. In this study, stability, contact angle and IFT measurements and multi-step core flooding tests were designed to investigate the effect of the ionic composition of smart water containing SO42− and Ca2+ ions in the presence of nanofluid on EOR processes. The amine/organosiloxane@Al2O3/SiO2 (AOAS) nanocomposite previously synthesized using co-precipitation-hydrothermal method has been used here. However, for the first time the application of this nanocomposite along with smart water has been studied in this research. Results show that by increasing the concentrations of calcium and sulfate ions in smart water, oil recovery is improved by 9% and 10%, respectively, compared to seawater. In addition, the use of smart water and nanofluids simultaneously is very effective on increasing oil recovery. Finally, the best performance was observed in smart water containing two times of sulfate ions concentration (SW2S) with nanofluids, showing increased efficiency of about 7.5%.


2018 ◽  
Vol 24 (8) ◽  
pp. 40
Author(s):  
Hussain Ali Baker ◽  
Kareem A. Alwan ◽  
Saher Faris Fadhil

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.  


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