Session: 10-07-01: Fluid Mechanics and Rheology of Nonlinear Materials and Complex Fluids

Paper Number: 112880

112880 - Experimental Study of Monovalent Salt and Hydrochloric Acid Solution Effects on the Stability of Blank Oil-Water Dispersion in Batch Separators 

Brief Abstract (Research Summary)

The effect of aqueous phase salinity and acidity on the stability of oil-water dispersion is poorly understood. This is because most research works make use of a complex solution of monovalent and divalent salts to replicate the composition of brine solution in the aqueous phase of crude oil emulsion. Hence, the relevance of each form of ionic solution cannot be determined without isolating and analyzing a laboratory-created oil-water dispersion. For this reason, this study aimed to investigate the impact of monovalent salt solution and acidic water on the stability of blank (emulsifier-free) oil-in-water (O/W) and water-in-oil (W/O) emulsions. Fluids were emulsified at a constant stirrer speed (2,500 rpm) and mixing duration (5 minutes) for each investigated emulsion. Mineral oil (EXXSOL D110) and distilled water with density and viscosity ratios of 0.805 and 0.330, respectively, were selected as pure fluids. Sodium chloride (NaCl) was used to vary the concentration of salt (from 1 to 60 g/L) in the aqueous phase, whereas a 1.0 M hydrochloric acid solution was used to alter the acidity (pH = 4.80 to 1.88) of distilled water. Experiments ranging from less than a minute to several hours were conducted using four water cuts (WC =25%, 50%, 75%, and 90%). The brine and acidic water phase had shown large impacts on the stability of O/W (90% and 75% WC) emulsions but had minor effects on W/O (25% and 50% WC) emulsions.

The Motivation for this work

In recent years, there has been a growing interest in investigating how emulsions, particularly brine water-in-crude oil (BW/CO), react to various salt ions and concentrations.  This is due to the fact that the main characteristic (stability) of BW/CO emulsion has changed significantly in response to the presence of different ions and concentrations in the aqueous phase. According to the literature, the presence and concentration of ionic solution  affected not only stability but also other emulsion properties  such as viscosity, droplet size, and interfacial tension (IFT).  It was also shown by literature that the higher dispersed phase fractions of BW/CO emulsion  enhance their apparent and relative viscosity due to an increase in the dispersed phase area-to-volume ratio of water droplets. However, the contribution of each salt ions to the destabilization (or stabilization) process remains unknown as a result of this complex mixture of ions (monovalent and divalent salts) in the aqueous phase . Furthermore, the majority of research in the literature has been devoted to the understanding of  BW/CO emulsion stability, viscosity, and droplet size, leaving insufficient details on how emulsions would behave when converted to CO/BW emulsions due to higher WCs.

Contribution of this Work

This study begins by investigating how the salinity (from 1-60g/L NaCl) as well as the acidity (from pH=4.80 to 1.88) affects the stability of laboratory-created O/W and W/O emulsion in the presence of no emulsifier at various water cuts (WCs), including 90%, 75%, 50%, and 25%. The goal of this investigation is to determine how monovalent salt and acidic solutions influence oil-water dispersion.

Data Collection Procedure

By swirling the oil and water phases with a 54 mm-diameter impeller, an initial emulsion volume of 200 ml was created. For each trial, the stirring speed and time were kept constant at 2500rpm and 5 minutes, respectively. Emulsions were created at a cutting-edge experimental facility known as the portable dispersion characterization rig (P-DCR). The development of the boundaries between each separated phase and the emulsion layer is recorded live in this facility. This procedure was carried out with the assistance of a high-resolution camera and sophisticated measurement tool to count the percentage of sedimented water and/or creamed oil that were in the emulsion layer before phase separation.

Presenting Author: K. Alanazi The University of Tulsa

Presenting Author Biography: Khalid Alanazi is a graduate of the Erosion/Corrosion Research Center (E/CRC) at the University of Tulsa (TU) and a Ph.D. candidate with the Tulsa University Separation Technology Projects (TUSTP) team. His current research interests include solid particle erosion (SPE) of engineering materials, two-phase flow, non-ionic surfactant stabilized oil-water dispersion, and emulsifier-free oil-water dispersion. He received his M.Sc. degree in mechanical engineering from TU in 2020 and his B.Sc. degree from the University of Tabuk (UT) in 2015. During his time at the E/CRC, he worked on a number of projects involving SPE in gas and liquid-dominated flows. Prior to joining TU, Alanazi was a teaching assistant at UT from 2016 to 2017, where he taught several courses in material engineering, material mechanics, and fluid mechanics.

Authors:

K. Alanazi The University of Tulsa
R. Mohan The University of Tulsa
S. S. Kolla Oklahoma State University
O. Shoham The University of Tulsa