Jitendra Sangwai

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.

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.

In this study, eight ionic liquids (ILs) from the two varieties of ILs, namely, aromatic and aliphatic ILs, have been considered to carry out experimental studies for their effect on the phase behavior of methane hydrate. We have employed five aromatic based ILs with several cations, such as 1-butyl-3-methyl imidazolium, 1-hexyl-3-methyl imidazolium, 1-octyl-3-methyl imidazolium and various anions, such as [Cl]−, [Br]−, [HSO4]−, and three aliphatic based ILs with various cations, such as di-ethyl-ammonium, tri-propyl-ammonium, tri-butyl-ammonium and [HSO4]− anion. All the experiments were performed in the hydrate equilibrium pressure and temperature ranges of 3.86–7.66 MPa and 276.68–283.18 K, respectively. It has been observed that all the investigated ILs have shown inhibition effect on methane hydrate system. Aromatic ionic liquids have shown their dominance over aliphatic ionic liquids in terms of methane hydrate inhibition. ILs with similar class of cation with varying carbon chain length have not shown significant improvement in hydrate inhibition. However, the replacement of anion by [HSO4]− in imidazolium-based ILs improves methane hydrate inhibition. 1-butyl-3-methyl imidazolium sulphate ([BMIM]+[HSO4]−) found to be the best methane hydrate inhibitor among all investigated ILs. In addition, a phase behavior model incorporating a single tuning parameter has been proposed to predict the phase behavior of methane hydrate in the presence of various ionic liquids and salt solutions. The absolute average deviation in pressure (AARD-P, %) for proposed model with an experimental data generated in this work and for various data sets from the literature has been found to be within ±2.90% of the experimental values. Both cation and anion of the ionic liquids have shown to exhibit inhibition effect on the methane hydrate phase stability. The study indicates that the selection of ionic liquids with tunable cation and anion may provide an opportunity to design the best inhibitor for methane hydrate.