MOLECULAR DYNAMICS SIMULATION STUDY OF OLEICBASED SURFACTANTS FOR ENHANCED OIL RECOVERY

• Main Author: SUHENDAR NIM:20516013, AANG
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/24881
• Institution: Institut Teknologi Bandung

Fast growing area for Palm plantation and production in Indonesia has made this <br /> <br /> country as one of the largest palm oil exporter in the world. This condition is <br /> <br /> inversely with crude oil production that is decreasing. Indonesia is one of the <br /> <br /> largest oil importer in the world. Surplus in palm oil production can be the solution <br /> <br /> for the crude oil deficiency. Oleic acid in palm oil can be used for basic material in <br /> <br /> surfactant production for enhanced oil recovery (EOR). Oleic-based surfactant is <br /> <br /> degradable surfactant that can also reduce polution risk that caused by usage of <br /> <br /> surfactants. This study is aimed to screen the potential surfactants for EOR by <br /> <br /> performing molecular dynamics (MD) simulation. Screening by MD simulation was <br /> <br /> choosen due to its low-cost and low-time consuming than experimental screening. <br /> <br /> All MD simulations were performed by using GROMACS 2016 software. The <br /> <br /> structure of oil model and surfactant candidates was sketched then coded and <br /> <br /> converted to readability format file for GROMACS. All those structures were then <br /> <br /> arranged in a simulation box and then solvated with simple water model. The <br /> <br /> system was minimized and equilibrated to reach simulation conditions target. Next <br /> <br /> step was simulation production and analysis of trajectory and energy files. The <br /> <br /> focus of this study was to screen the potential nonionic surfactants that suitable for <br /> <br /> high salinity and temperature that typicaly found in most oil reservoir in Indonesia. <br /> <br /> In this study, two types oleic-based surfactants were designed: peptide-oliec and <br /> <br /> PEGn-oleic surfactants. The screening of potential surfactants by MD simulations <br /> <br /> were based on their ability to reduce interfacial tension (IFT) between water and <br /> <br /> oil layers, their ability to emulsify oil molecules, and their wetability towards core <br /> <br /> rocks in order to replace strongly adsorped oil. The result of MD simulations <br /> <br /> revealed the best nonionic peptide-oleic surfactant was (Ala)3-Oleic. This <br /> <br /> surfactant was screened based on its ability to reduce IFT value when it was placed <br /> <br /> between oil and water layers. The IFT reduction level for (Ala)3-Oleic was 3,60 <br /> <br /> dyne/cm. While for PEGn-oleic surfactant the best was exhibited by PEG100-oleic <br /> <br /> and PEG400-oleic, where its IFT reduction level were about 3.99 and 4,08 dyne/cm <br /> <br /> respectively. Unfortunately, peptide–oleic surfactants has high-cost in their <br /> <br /> synthesis. For this economical reason, next simulation performed to PEG100-oleic <br /> <br /> and PEG400-oleic surfactants only. Termal stability simulation of PEG100-oleic and <br /> <br /> PEG400-oleic surfactants showed that they have ability to reduce IFT value at 30 – <br /> <br /> 90 oC and the best performance was exhibited by PEG400-oleic with IFT reducing <br /> <br /> level about 4,68 dyne/cm at 70 oC. Those surfactants were then further examined <br /> <br /> its performace by evaluating its ability to emulsify oil molecules that represented <br /> <br /> iv <br /> <br /> by octadecane. In this step, the condition of system was tried to mimic the real oil <br /> <br /> well condition. To the simulation box Na+, Ca2+, Mg2+, CO3 <br /> <br /> 2-, HCO3 <br /> <br /> - and Cl- ions <br /> <br /> was added with their concentration about 289, 12, 20, 3, 43, 275 mM respectively. <br /> <br /> The results showed that both of them were able to emulsify octadecanes but with <br /> <br /> different rates and contact number between surfantants and oil. PEG400-oleic <br /> <br /> surfactant has faster rate and higher contact number. It can emulsify oil molecules <br /> <br /> less than 1 ns and average number contact about 3500. While PEG100-oleic emulsify <br /> <br /> the oil molecules around 3 ns with average contact number about 3000. The last <br /> <br /> test to get the best surfactant was the wetability test. The simulation gave the result <br /> <br /> that both PEG100-oleic and PEG400-oleic were able to change wetability of rocks <br /> <br /> from oil-wet to water-wet. Accordingly, PEG400-oleic is the best nonionic surfactant <br /> <br /> candidate due to its performance in each simulation test.