scholarly journals Numerical modeling and experimental investigation on the effect of low-salinity water flooding for enhanced oil recovery in carbonate reservoirs

2021 ◽  
Vol 11 (2) ◽  
pp. 925-947
Author(s):  
Erfan Hosseini ◽  
Mohammad Sarmadivaleh ◽  
Dana Mohammadnazar

AbstractNumerous studies concluded that water injection with modified ionic content/salinity in sandstones would enhance the oil recovery factor due to some mechanisms. However, the effects of smart water on carbonated formations are still indeterminate due to a lack of experimental investigations and researches. This study investigates the effects of low-salinity (Low Sal) solutions and its ionic content on interfacial tension (IFT) reduction in one of the southwestern Iranian carbonated reservoirs. A set of organized tests are designed and performed to find each ion’s effects and total dissolved solids (TDS) on the candidate carbonated reservoir. A sequence of wettability and IFT (at reservoir temperature) tests are performed to observe the effects of controlling ions (sulfate, magnesium, calcium, and sodium) and different salinities on the main mechanisms (i.e., wettability alteration and IFT reduction). All IFT tests are performed at reservoir temperature (198 °F) to minimize the difference between reservoir and laboratory-observed alterations. In this paper, the effects of four different ions (SO42-, Ca2+, Mg2+, Na+) and total salinity TDS (40,000, 20,000, 5000 ppm) are investigated. From all obtained results, the best two conditions are applied in core flooding tests to obtain the relative permeability alterations using unsteady-state methods and Cydarex software. The final part is the simulation of the whole process using the Schlumberger Eclipse black oil simulator (E100, Ver. 2010) on the candidate reservoir sector. To conclude, at Low Sal (i.e., 5000 ppm), the sulfate ion increases sulfate concentration lower IFT, while in higher salinities, increasing sulfate ion increases IFT. Also, increasing calcium concentration at high TDS (i.e., 40,000 ppm) decreases the amount of wettability alteration. In comparison, in lower TDS values (20,000 and 5000 ppm), calcium shows a positive effect, and its concentration enhanced the alteration process. Using Low Sal solutions at water cut equal or below 10% lowers recovery rate during simulations while lowering the ultimate recovery of less than 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.  


2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
Alibi Kilybay ◽  
Bisweswar Ghosh ◽  
Nithin Chacko Thomas

In the oil and gas industry, Enhanced Oil Recovery (EOR) plays a major role to meet the global requirement for energy. Many types of EOR are being applied depending on the formations, fluid types, and the condition of the field. One of the latest and promising EOR techniques is application of ion-engineered water, also known as low salinity or smart water flooding. This EOR technique has been studied by researchers for different types of rocks. The mechanisms behind ion-engineered water flooding have not been confirmed yet, but there are many proposed mechanisms. Most of the authors believe that the main mechanism behind smart water flooding is the wettability alteration. However, other proposed mechanisms are interfacial tension (IFT) reduction between oil and injected brine, rock dissolution, and electrical double layer expansion. Theoretically, all the mechanisms have an effect on the oil recovery. There are some evidences of success of smart water injection on the field scale. Chemical reactions that happen with injection of smart water are different in sandstone and carbonate reservoirs. It is important to understand how these mechanisms work. In this review paper, the possible mechanisms behind smart water injection into the carbonate reservoir with brief history are discussed.


2019 ◽  
Vol 10 (4) ◽  
pp. 1551-1563 ◽  
Author(s):  
Siamak Najimi ◽  
Iman Nowrouzi ◽  
Abbas Khaksar Manshad ◽  
Amir H. Mohammadi

Abstract Surfactants are used in the process of chemical water injection to reduce interfacial tension of water and oil and consequently decrease the capillary pressure in the reservoir. However, other mechanisms such as altering the wettability of the reservoir rock, creating foam and forming a stable emulsion are also other mechanisms of the surfactants flooding. In this study, the effects of three commercially available surfactants, namely AN-120, NX-1510 and TR-880, in different concentrations on interfacial tension of water and oil, the wettability of the reservoir rock and, ultimately, the increase in oil recovery based on pendant drop experiments, contact angle and carbonate core flooding have been investigated. The effects of concentration, temperature, pressure and salinity on the performances of these surfactants have also been shown. The results, in addition to confirming the capability of the surfactants to reduce interfacial tension and altering the wettability to hydrophilicity, show that the TR-880 has the better ability to reduce interfacial tension than AN-120 and NX-1510, and in the alteration of wettability the smallest contact angle was obtained by dissolving 1000 ppm of surfactant NX-1510. Also, the results of interfacial tension tests confirm the better performances of these surfactants in formation salinity and high salinity. Additionally, a total of 72% recovery was achieved with a secondary saline water flooding and flooding with a 1000 ppm of TR-880 surfactant.


Low salinity and carbonated water flooding have been investigated as possible techniques of improved/enhanced oil recovery. Carbonated water injection consists of dissolving carbon dioxide CO2 in water prior to injection and could be considered as a way to store greenhouse gas safely. Low salinity water flooding is a process of diluting high salinity injection water to a very low level of salinity. In this project, the effect of combining the two techniques in a sequential flooding was studied. The primary aim of this study is to optimize the oil recovery and evaluate CO2 storage during this process, employing low permeability carbonate cores and different sequential carbonated and non-carbonated brines flooding. Formation brine, seawater, low salinity carbonated and non-carbonated were used in this work. Core samples grouped as composite cores with similar over all reservoir permeability. Different sequences of brines were employed to determine the optimum system. The experiment's result showed that carbonated water performs better than the noncarbonated brines. A new technique for estimate CO2 retention based on the displacement efficiency of the carbonated water flooding system is presented. The interfacial tension, contact angle measurements results indicated that wettability is the dominant mechanism of the studied systems. A sequential composite core flooding consists of carbonated low salinity followed by low salinity and seawater injection (CLSW- LSW-SW) is the optimum flooding system among the studied systems. Technically, CLSW flooding displayed an excellent incremental displacement efficiency ∆DE of 21.4% and CSW exhibited the best CO2 retention per incremental ∆Np.


RSC Advances ◽  
2020 ◽  
Vol 10 (69) ◽  
pp. 42570-42583
Author(s):  
Rohit Kumar Saw ◽  
Ajay Mandal

The combined effects of dilution and ion tuning of seawater for enhanced oil recovery from carbonate reservoirs. Dominating mechanisms are calcite dissolution and the interplay of potential determining ions that lead to wettability alteration of rock surface.


Polymers ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1227 ◽  
Author(s):  
Muhammad Tahir ◽  
Rafael E. Hincapie ◽  
Nils Langanke ◽  
Leonhard Ganzer ◽  
Philip Jaeger

The injection of sulfonated-modified water could be an attractive application as it results in the formation of a mechanically rigid oil-water interface, and hence, possible higher oil recovery in combination with polymer. Therefore, detailed experimental investigation and fluid-flow analysis into porous media are required to understand the possible recovery mechanisms taking place. This paper evaluates the potential influence of low-salt/sulfate-modified water injection in oil recovery using a cross-analyzed approach of coupled microfluidics data and core flooding experiments. Fluid characterization was achieved by detailed rheological characterization focusing on steady shear and in-situ viscosity. Moreover, single and two-phase micromodels and core floods experiments helped to define the behavior of different fluids. Overall, coupling microfluidics, with core flooding experiments, confirmed that fluid-fluid interfacial interaction and wettability alteration are both the key recovery mechanisms for modified-water/low-salt. Finally, a combination of sulfate-modified/low-salinity water, with polymer flood can lead to ~6% extra oil, compared to the combination of polymer flood with synthetic seawater (SSW). The results present an excellent way to make use of micromodels and core experiments as a supporting tool for EOR processes evaluations, assessing fluid-fluid and rock-fluid interactions.


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.


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%.


2019 ◽  
Vol 141 (7) ◽  
Author(s):  
Yanan Ding ◽  
Sixu Zheng ◽  
Xiaoyan Meng ◽  
Daoyong Yang

In this study, a novel technique of low salinity hot water (LSHW) injection with addition of nanoparticles has been developed to examine the synergistic effects of thermal energy, low salinity water (LSW) flooding, and nanoparticles for enhancing heavy oil recovery, while optimizing the operating parameters for such a hybrid enhanced oil recovery (EOR) method. Experimentally, one-dimensional displacement experiments under different temperatures (17 °C, 45 °C, and 70 °C) and pressures (about 2000–4700 kPa) have been performed, while two types of nanoparticles (i.e., SiO2 and Al2O3) are, respectively, examined as the additive in the LSW. The performance of LSW injection with and without nanoparticles at various temperatures is evaluated, allowing optimization of the timing to initiate LSW injection. The corresponding initial oil saturation, production rate, water cut, ultimate oil recovery, and residual oil saturation profile after each flooding process are continuously monitored and measured under various operating conditions. Compared to conventional water injection, the LSW injection is found to effectively improve heavy oil recovery by 2.4–7.2% as an EOR technique in the presence of nanoparticles. Also, the addition of nanoparticles into the LSHW can promote synergistic effect of thermal energy, wettability alteration, and reduction of interfacial tension (IFT), which improves displacement efficiency and thus enhances oil recovery. It has been experimentally demonstrated that such LSHW injection with the addition of nanoparticles can be optimized to greatly improve oil recovery up to 40.2% in heavy oil reservoirs with low energy consumption. Theoretically, numerical simulation for the different flooding scenarios has been performed to capture the underlying recovery mechanisms by history matching the experimental measurements. It is observed from the tuned relative permeability curves that both LSW and the addition of nanoparticles in LSW are capable of altering the sand surface to more water wet, which confirms wettability alteration as an important EOR mechanism for the application of LSW and nanoparticles in heavy oil recovery in addition to IFT reduction.


2018 ◽  
Vol 37 (1) ◽  
pp. 355-374 ◽  
Author(s):  
Yeonkyeong Lee ◽  
Hyemin Park ◽  
Jeonghwan Lee ◽  
Wonmo Sung

The low-salinity waterflooding is an attractive eco-friendly producing method, recently, for carbonate reservoirs. When ferrous ion is present in the formation water, that is, acidic water, the injection of low-salinity water generally with neutral pH can yield precipitation or dissolution of Fe-minerals by pH mixing effect. FeSO4 and pyrite can be precipitated and re-dissolved, or vice versa, while siderite and Fe(OH)2 are insoluble which are precipitated, causing permeability reduction. Particularly, pyrite chemically reacts with low-salinity water and release sulfate ion, altering the wettability, favorably, to water-wet. In this aspect, we analyzed oil production focusing on dissolution of Fe-minerals and Fe-precipitation using a commercial compositional reservoir simulator. From the simulation results, the quantities of precipitation and dissolution were enormously large regardless of the type of Fe-minerals and there was almost no difference in terms of total volume in this system. However, among Fe-minerals, Fe(OH)2 precipitation and pyrite dissolution were noticeably large compared to troilite, FeSO4, and siderite. Therefore, it is essential to analyze precipitation or dissolution for each Fe-mineral, individually. Meanwhile, in dissolving process of pyrite, sulfate ions were released differently depending on the content of pyrite. Here, the magnitude of the generated sulfate ion was limited at certain level of pyrite content. Thus, it is necessary to pay attention for determining the concentration of sulfate ion in designing the composition of injection water. Ultimately, in the investigation of the efficiency of oil production, it was found that the oil production was enhanced due to an additional sulfate ion generated from FeS2 dissolution.


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