Thermothickening and Salinity Tolerant Hydrophobically Modified Polyacrylamides for Polymer Flooding

Abstract

Partially hydrolyzed polyacrylamide (HPAM) is by far the most used synthetic polymer in enhanced oil recovery (EOR) projects. Shortcomings of HPAM include a highly molecular weight (M w) dependent viscosity yield and decreasing viscosifying ability with increasing salinity and temperature. For an economically viable project, this limits its use to reservoirs with low to moderate salinities and temperatures. In that respect, hydrophobically modified polyacrylamides (HMPAM) has been suggested as an alternative for applications at higher salinities and temperatures. While studies have compared the performance of modified versus unmodified commercial EOR polymers at different salinities and temperatures, and the structure–property relationship of monodisperse, low M w HMPAM, published data on the simultaneous effect of polymer hydrophobicity, salinity, and temperature for commercial EOR polymers are limited. This study thus presents a comprehensive series of experiments to investigate the effect of polymer hydrophobicity on viscosifying ability as a function of salinity and temperature. The main findings of these experiments are that the balance between salinity effects and thermal behavior shifts the order of viscosifying ability so that the polymer with the best viscosifying abilities at low temperatures and salinities is outperformed at conditions of high salinity and temperature. This highlights the importance of structure–activity studies at relevant reservoir conditions prior to selection of a solution for field application.

Water Control with Gels Based on Synthetic Polymers under Extreme Conditions in Oil Wells

“…The viscosity of both polymers increased with rising temperature to a maximum temperature at 10 wt % of salinity. [180] hydrolysis degree. So, 10 wt % of AMPS was found to be the optimal concentration, where the thermal stability is attributed to VP units in the terpolymer, while salinity stability to the AMPS unit [149].…”

Polyelectrolyte–Dye Interactions: An Overview

“…Upon the increase in the concentration of added salt (ions), the gradual transition from an elongated to a random coil conformation (decrease in viscosity) is favored due to the effective screening of the ionic charges of the monomeric units via counterion condensation. This also decreases the intermolecular electrostatic repulsion, i.e., the intermolecular attraction increases, which thereby raises their solution viscosity [ 40 ]. Polyelectrolytes have been hydrophobically modified to provide an improved thickening effect and for building intense three-dimensional networks [ 41 ].…”

“…Polyelectrolytes based on polyurathanes, hydroxyethylcellulose, and alkali swellable acrylates have demonstrated promising results in improving the performance and binding ability of water-borne coatings [ 45 ]. Polyacrylamides have also been hydrophobically modified to demonstrate a high viscosity yield under highly saline conditions, and have shown promising applications in oil field recovery [ 40 , 46 ].…”

High‐viscoelastic graft modified chitosan hydrophobic association polymer for enhanced oil recovery

“…Among various recovery-enhancing polymers, partially hydrolyzed polyacrylamide (HPAM) is the most commonly used. [5][6][7] However, HPAM shows limited thermal stability and cannot withstand high salinity, which limits the field application of tertiary oil recovery. [8][9][10] In this context, there is a large demand for stable new polymers in the harsh reservoir environment.…”

“…Therefore, it is of great significance to strengthen the research of polymer flooding oil recovery technology, and there is also plenty of development space. Among various recovery‐enhancing polymers, partially hydrolyzed polyacrylamide (HPAM) is the most commonly used 5–7 . However, HPAM shows limited thermal stability and cannot withstand high salinity, which limits the field application of tertiary oil recovery 8–10 .…”