Now showing 1 - 10 of 13
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    Interfacial tension of crude oil-water system with imidazolium and lactam-based ionic liquids and their evaluation for enhanced oil recovery under high saline environment
    (01-03-2017)
    Sakthivel, Sivabalan
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    Velusamy, Sugirtha
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    Nair, Vishnu Chandrasekharan
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    Sharma, Tushar
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    Matured reservoirs are being targeted for enhanced oil recovery (EOR) operations in the hope to recover the residual oil that remains trapped within the porous media. Chemical enhanced oil recovery is one of the successful oil recovery methods which is being employed for the recovery of the residual oil. Many of the conventional chemicals fail to perform under high temperature and high saline reservoir conditions. These situations lead to the search for alternate flooding techniques which could efficiently produce the crude oil to the surface. The present work investigates a possible solution for the recovery of trapped crude oil using lactam and imidazolium based ionic liquids (ILs) specifically targeted towards recovery in high saline environment. Initially, the interfacial tension of the crude oil-water system has been investigated using various chemical agents, such as sodium dodecyl sulfate (SDS), and six different ILs at varying high saline concentrations as a function of temperature (283.15–353.15 K). Subsequently, flooding experiments with only polymer, only SDS, only IL, SDS + polymer and IL + polymer at zero and high saline conditions were performed. It was observed that the IL + polymer flood performed very well in both zero and high salinity conditions as compared to all other flooding systems. The present investigation also portrays an intuition on the evaluation of ILs based on their alkyl chain length.
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    Eco-efficient and green method for the enhanced dissolution of aromatic crude oil sludge using ionic liquids
    (01-01-2014)
    Sakthivel, Sivabalan
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    Velusamy, Sugirtha
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    The upstream petroleum industry faces operational and technical problems due to increased deposition of waxes, aromatics and asphaltene from crude oil sludge in oil storage tanks in the form of tank-bottom sludge (TBS). This results in huge production losses, and threatens environmentally safe operation; therefore, safer solutions are needed. In this work, nine aromatic ionic liquids (ILs) are synthesized and tested for the dissolution of TBS with the aid of five solvents, namely, toluene, heptane, decane, ethyl acetate and hexane. The UV absorbance values of the standard solutions (TBS in solvent) are compared with the sample solutions (TBS in solvent + ILs). It is observed that ILs significantly improve the dissolution of TBS in solvents compared with neat solvent alone. Different weight ratios of TBS : ILs (1 : 1, 1 : 0.5 and 1 : 0.1) are considered in this study. Ionic liquids (ILs) based on an imidazolium cation and various anions, such as [Cl]-, [Br]-, [BF 4]-, [H2PO4]-, [HSO 4]-, and [PF6]-, are considered in this investigation. It is observed that the dissolution of TBS in heptane in the presence of [HMIM]+[Br]- is efficient to a maximum extent of 66% with other solvents showing similar increased solubility effect with various ILs. In the case of hexane, it should be noted that the efficiency of dissolution of TBS goes on decreasing with increasing concentration of TBS in hexane. A hold-time study is also performed with heptane containing ILs and heptanes without ILs to determine the maximum time required for efficient dissolution of TBS. It is observed that the efficiency is increased beyond 66% in the presence of ILs for the dissolution of TBS in heptane, provided that the mixture of solvent and ILs are in contact with the TBS for a prolonged period of 30 days, or even longer as required. FT-IR and 13C-NMR spectral analyses are also performed so as to understand the efficiency of the ILs in the dissolution of TBS in various solvents, and it was observed that there is a decrease in the intensity of the peaks in the spectra of treated TBS with solvents, which is further enhanced by the addition of ILs. This journal is © the Partner Organisations 2014.
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    Imidazolium-based ionic liquids as an anticorrosive agent for completion fluid design
    (01-10-2017)
    Velusamy, Sugirtha
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    Sakthivel, Sivabalan
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    Most of the onshore and offshore oil and gas reservoirs are facing operational challenges due to high temperature and high salinity, thus requiring advanced techniques for realizing the expected oil recovery with the use of specially designed chemicals. During oil and gas well development, completion fluids, which are solids-free liquids, are used to complete an oil or gas well. Completion fluids consisting of brines are primarily used for oil and gas well stabilization and are corrosive in nature. There is a need to develop additives to be added with completion fluids to address the corrosive nature. The present investigation involved the usage of two imidazolium ionic liquids (ILs) as corrosion inhibitors for mild steel in various completion brine (CaCl2, HCOOCs and ZnBr2) fluids. The study was performed using various techniques, such as, potentiodynamic polarization, weight loss measurements and exposure studies. All the above techniques showed promising results which indicated that the ILs as corrosion inhibitors used were of the mixed-type following both physisorption and chemisorption over the mild steel surface. Among the two inhibitors studied here, 1-octyl-3-methyl imidazolium chloride ([OMIM]+[Cl]-) with longer alkyl chain exhibited better inhibition efficiency and much lesser corrosion rate than 1-butyl-3-methyl imidazolium chloride ([BMIM]+[Cl]-) with a shorter alkyl chain. The results obtained from various methodologies indicate that ionic liquids can be explored to develop anti-corrosive completion fluids suitable for oil and gas reservoirs.
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    Use of aromatic ionic liquids in the reduction of surface phenomena of crude oil-water system and their synergism with brine
    (28-01-2015)
    Sakthivel, Sivabalan
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    Velusamy, Sugirtha
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    Enhanced oil recovery is governed primarily by the role of interfacial tension between crude oil and water. Interfacial tension (IFT) of the crude oil-water system is one of the vital factors in the analysis of the capillary forces affecting trapped oil within the reservoir rocks. High salinity and temperature of the reservoirs tend to make researchers search for new surfactants to lower the interfacial tension in crude oil-water systems. The current study hopes to create a move toward solving the above problem through the use of aromatic ionic liquids (ILs) based on imidazolium as the cation and various anions such as [Cl]-, [Br]-, [BF4]-, [H2PO4]-, [HSO4]-, and [PF6]- in different concentrations. This work involves the study of the effect of concentration, temperature, time, and brine on the fate of surface tension (SFT) of water and interfacial tension of crude oil-water systems. The present study also addresses the trend in the electrical conductivity of ILs in water along with the effect of temperature and concentration of ILs. The study reveals that these ILs are effective in reducing the SFT and IFT of water and crude oil-water systems at high salinity and temperature conditions. In the IFT measurements, a linear decrement with increase in temperature is observed for crude oil-water in the presence of ILs. The interfacial tension of the various imidazolium-based ionic liquids with the crude oil-water system has been measured as a function of temperature by means of the Wilhelmy plate method. The influence of the nature of cation and anion of ionic liquids and of the chain length on the cationic head of the ILs on interfacial tension is also discussed in detail. At increased salinity conditions, unlike classical surfactants, these ILs are found to be more successful. Enhanced efficiency of the drop in IFT using NaCl and IL mixture has been confirmed by measuring the IFT between crude oil and the aqueous solution of IL. The synergism of salt and IL mixture on the reduction of IFT has been observed.
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    Evaluation of ionanofluid for chemical-enhanced oil recovery for matured crude oil reservoirs
    (01-01-2022)
    Sharma, Ankit
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    Kakati, Abhijit
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    Sakthivel, Sivabalan
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    Jadhawar, Prashant
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    The purpose of the present work is to evaluate applicability of ionanofluids for enhanced oil recovery (EOR) applications. Two different ionanofluids have been prepared for this study by adding silica nanoparticles into two different ionic liquids (tripropyl ammonium sulphate and triethyl ammonium sulphate) solutions. The effects of nanoparticle and ionic liquid on the interfacial tension of crude oil-nanofluid and their enhanced oil recovery performances have been evaluated. Ionanofluids are found to have the ability to reduce the interfacial tension to a significantly low value. The results of this study also indicate that ionanofluids has much higher enhanced oil recovery efficiencies in comparison to nanofluid and ionic liquid alone. Therefore, ionanofluids have the potential to be used as an excellent future EOR agent.
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    Effect of Imidazolium-Based Ionic Liquids on the Interfacial Tension of the Alkane-Water System and Its Influence on the Wettability Alteration of Quartz under Saline Conditions through Contact Angle Measurements
    (22-11-2017)
    Velusamy, Sugirtha
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    Sakthivel, Sivabalan
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    Depleted matured reservoirs contain almost two-thirds trapped oil, which remains unrecovered even after primary and secondary oil recovery methods. Chemical enhanced oil recovery (EOR) methods involve the usage of chemical agents that improve the mobility of the residual oil by mechanisms involving alteration of wettability, viscous fingering reduction within the pay zone, and interfacial tension (IFT) between interfaces of fluids (oil/water) and rock, followed by reduced capillary forces during flooding. Chemical EOR methods need more research for high saline reservoir conditions. In this work, the effect of six imidazolium ionic liquids (ILs) on the IFT of alkane-water systems and alteration of wettability of quartz surface was investigated as a function of IL concentration (0-10000 ppm) and temperature (288.15, 298.15, 308.15, and 318.15 K). Initially, the effect of the various ILs on the IFT of the alkane-aqueous IL system was studied and compared with the neat alkane-water system. Subsequently, synergistic behavior of the ILs + NaCl (0-200000 ppm NaCl) on the system of alkane-aqueous IL + NaCl was performed and compared with the alkane-aqueous IL system at zero salinity. Thereafter, the wettability alteration of quartz-alkane-aqueous IL and quartz-crude oil-aqueous IL systems, under both zero and high salinity conditions at 298.15 K at atmospheric pressure, was studied using contact angle measurements. The systems with IL showed an increase of contact angle exhibiting an alteration in the wettability from water wet to oil wet, whereas the systems under saline conditions showed a wettability from oil wet to water wet. A synergistic effect of ILs with salt on IFT reduction and wettability alteration has been detected. It is suggested that longer ILs could be a better option for EOR application.
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    Spectroscopic investigations to understand the enhanced dissolution of heavy crude oil in the presence of lactam, alkyl ammonium and hydroxyl ammonium based ionic liquids
    (01-09-2016)
    Sakthivel, Sivabalan
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    The deposition of crude oil in various production and surfaces facilities such as oil storage tanks in the form of tank-bottom sludge, pipeline deposition, skin formation at the near well-bore, deposition in the tubing leads to blockage which invites several operational challenges. These challenges, in turn bring about huge production losses, involvement of scarce human resources, and threatening the environmentally safe operation, thus needing safer solutions. An environmental-friendly method for the dissolution of heavy crude oil (HCO) with the use of ionic liquids (ILs) along with a paraffinic liquid hydrocarbon (organic solvent) is developed which is considered to be very helpful for easy pumping, reducing the risk of manual cleaning and time consumption. In this work, eleven ILs are selected from lactam, alkyl ammonium and hydroxyl ammonium families with various anions, such as, [HCOO]-, [CH3COO]-, [CF3COO]-, [C6H13COO]-. The results on the quantitative and qualitative dissolution of the HCO using organic solvents (with and without ionic liquids) are presented. Studies on the quantitative dissolution of crude oil are performed with the use of UV-vis spectrophotometer, while the qualitative information on the dissolution of HCO are carried out using FT-IR and 13C NMR techniques. In the case of sample system (HCO + solvent + ILs), the increase in solubility observed is up to a maximum of 80%. Time-hold study was conducted for a prolonged period of 30 days where the increase in solubility is improved in the range of 80-335% with the addition of ILs along with organic solvents, whereas standard system (without ILs), showed improvement in the range of 11-16% only. This method helps in increasing the efficacy of organic solvents, such as, the liquid hydrocarbons which would be suitable for upstream petroleum engineering application. Moreover, the used ionic liquids were recycled and can also be reused.
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    Adsorption of aliphatic ionic liquids at low waxy crude oil-water interfaces and the effect of brine
    (05-03-2015)
    Sakthivel, Sivabalan
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    Velusamy, Sugirtha
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    The need for development of better surface active agents for upstream oil and gas industry which can survive harsh condition of salinity are in great demand, particularly for the applications related to improved/enhanced oil recovery, flow assurance and oil and gas production operations keeping in mind the environmental constraints. The technical difficulties which need to be considered are those involving the surface forces such as surface tension (SFT) and interfacial tension (IFT) acting between the formation water and the low waxy crude oil. In this study, we have employed the use of eight aliphatic ionic liquids (ILs), based on di- and tri-alkyl ammonium as cations and with various anions such as [CH3COO]-, [BF4]-, [H2PO4]- and [HSO4]- for the investigation of the surface phenomenon of crude oil-water system. The synergistic effect of NaCl along with the ILs is investigated in detail. It is observed that there is a significant reduction in the surface tension of water and the interfacial tension of crude oil-water system in the presence of salt, particularly at higher concentration of NaCl (200,000ppm). Effect of temperature, time, alkyl chain length of the cationic part of the ILs, nature of anions of ILs and the concentration of ILs is also discussed. The trend in the electrical conductivity of aqueous IL solutions with various concentrations at three different temperatures 298.15-318.15K is also presented along with critical aggregation concentration. The study on the effect of ILs on the SFT/IFT of water and low waxy crude oil-water system reveal that the ILs are successful in minimizing the effect of the surface forces in the presence of salt and thereby, could pave the way for efficient enhanced oil recovery operations.
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    Effects of Imidazolium-Based Ionic Liquids on the Rheological Behavior of Heavy Crude Oil under High-Pressure and High-Temperature Conditions
    (17-08-2017)
    Velusamy, Sugirtha
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    Sakthivel, Sivabalan
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    The production, processing, and transportation of heavy crude oil (HCO) is difficult because of its high viscosity. For practical applications, information on the rheological behavior of HCO plays an important role, especially in flow assurance investigations. In this work, six different imidazolium ionic liquids (ILs) were tested for their effects on the rheological behavior of HCO under high-pressure and high-temperature conditions. The rheological studies were carried out at three different pressures (0.1, 5, and 10 MPa) and four experimental temperatures (298.15, 323.15, 348.15, and 373.15 K). The HCO + IL systems showed favorable viscosity reductions of 26.5% and 31.5% for the systems of HCO + 1-butyl-3-methylimidazolium chloride ([BMIM]+[Cl]-) and HCO + 1-octyl-3-methylimidazolium chloride ([OMIM]+[Cl]-), respectively, at 298.15 K and 0.1 MPa as compared to the pure HCO system. At 298.15 K and 0.1 MPa, the yield stress of the HCO + IL systems was reduced by about 15-20%, whereas when the temperature was increased to 373.15 K, the yield stress decreased in the range of 25-30% as compared to that of neat HCO. The viscoelastic moduli of the HCO sample at 0.1 MPa, 298.15 K, and about 1.5% strain were found to be G′ (storage modulus) ≈ 11 Pa and G″ (loss modulus) ≈ 7 Pa, indicating that the HCO sample was solidlike, whereas for the HCO + IL systems, the G′ and G″ values were reduced to ∼7 and 3 Pa, respectively. The crossover frequency of the HCO + IL systems was reduced to the range of 25-30% as compared to that of pure HCO. From the various measurements, it was observed that the addition of the ILs to the HCO resulted in improved rheological properties compared to those of the pure HCO system. Further, the results of the microscopic investigation also supported the rheological studies, indicating that the addition of the ILs helped to break the large flocculated structures of HCO into smaller spheres. It was also observed that the IL with the longer alkyl chain length provided greater efficiency in the viscosity reduction with favorable viscoelastic behavior.
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    Experimental investigation on the effect of aliphatic ionic liquids on the solubility of heavy crude oil using UV-visible, Fourier transform-infrared, and 13C NMR spectroscopy
    (18-09-2014)
    Sakthivel, Sivabalan
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    Velusamy, Sugirtha
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    Chemical treatment of aromatic heavier hydrocarbons are traditionally done by using cyclic aromatic nonpolar solvents, such as benzene, xylene, and toluene, which have the capability to dissolve asphaltenes. However, these aromatic solvents are volatile and hazardous and hence not advisable to use. Alternatively, lighter hydrocarbons, such as heptane, hexane, etc., show lesser solubility. It is, therefore, crucial that these problems require intelligent, cost-effective, and innovative solutions. The present work investigates the possible solution for the dissolution of heavy crude oil using the application of eight aliphatic ionic liquids (ILs) along with five solvents, namely, toluene, heptane, decane, ethyl acetate, and hexane. Ionic liquids (ILs) based on [CH3COO]-, [BF4]-, [H2PO4]-, and [HSO4]- as anions and with various cations, such as di- and tri-alkyl ammonium, are considered. The enhancement in the solubility of heavy crude oil in solvent + ILs mixture is investigated using Ultraviolet - visible (UV - vis) spectrophotometry, Fourier transform-infrared spectroscopy (FT-IR), and 13C-nuclear magnetic resonance (NMR) spectroscopic techniques. The absorbance of the sample solution (heavy crude oil + solvent + IL) is compared with the standard solution (heavy crude oil in neat solvent alone). It is observed that the dissolution of heavy crude oil is more in the solution with IL than with the solvent alone. Solubility of heavy crude oil in solvents increases to about 70% in the presence of ILs. Hold-time study is also performed to understand the maximum time required for efficient dissolution of heavy crude oil. The hold-time study reveals that solubility of heavy crude oil in heptane increased to about 61-222% in the presence of ILs, as compared to 11-16% in the case of standard solution for a prolonged period of 30 days.