Experimental Studies on the Phase Behavior of an Alcohol-Surfactant Mixture at Varying Conditions of Temperature, Water to Oil Ratio, Cosolvent and Pressure
Open Access
- Author:
- Abboud, Hafsa Abubaker
- Graduate Program:
- Energy and Mineral Engineering
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- May 29, 2020
- Committee Members:
- Russell Taylor Johns, Dissertation Advisor/Co-Advisor
Russell Taylor Johns, Committee Chair/Co-Chair
Gregory R King, Committee Member
Eugene C Morgan, Committee Member
Andrew Leonard Belmonte, Outside Member
Mort D Webster, Program Head/Chair - Keywords:
- EOR
Surfactant
Microemulsion
Pressure
WOR - Abstract:
- Surfactant flooding is a chemical enhanced oil recovery technique which has shown promise as an EOR method for the recovery of oil from maturing oil fields. It involves the injection of the surfactant mixture (surfactant and co-surfactant or solvent) into the reservoir to reduce the interfacial tension between the oil and water by creating a third phase (microemulsion) that contains equal amounts of oil and water. This reduction in the interfacial tension will allow for the production of the immobile oil that was previously trapped in the reservoir pores. For a successful surfactant EOR operation, the optimum surfactant formulation is necessary. In order to obtain the correct formulation for the selected reservoir a proper understanding of the effect of the different parameters on the phase behavior is needed. This includes considering the effects of salinity, high temperatures, high pressures and the equivalent alkane carbon number (EACN) among other considerations. While a significant number of studies have been done on surfactants in the past, very few papers have been published dealing with the combined effects of pressure and temperature on the multiphase microemulsion system. In this study we performed an extensive array of surfactant experiments at varying conditions of temperature, salinity, concentration, water-oil ratio (WOR), pressure and EACN for the same surfactant, therefore providing a comprehensive set of experimental results on the effect of the varying parameters on the phase behavior and solubilities using the selected surfactant. The effects of both alcohol and salt partitioning between the phases was investigated, empirical relations were developed to model the partitioning coefficients and the results were included in the interpretation of the surfactant microemulsion phase behavior. The results indicated that both alcohol and salt partitioning can affect the phase behavior and excluding either one can result in inaccurate interpretation of the phase behavior results. High pressure experiments were conducted on the same surfactant system at differing compositions to study the effect of pressure on the phase behavior, which showed that pressure can have a significant effect on the changes on phase behavior, shifting it from three phases to two phases and vice-versa. The changes in phase type and the location of the phase boundaries have been shown to depend on several factors which include temperature, the range of the three-phase window and how far the selected composition point is from the phase boundary. The results of these experiments were used to capture the main parameters of the HLD-NAC EoS that is used in the simulation model for surfactant calculations. The model results after tuning the parameters show good agreement when compared to the examined experimental data.