Partially hydrolyzed polyacrylamide: enhanced oil recovery applications, oil-field produced water pollution, and possible solutions

Abstract

Polymers, such as partially hydrolyzed polyacrylamide (HPAM), are widely used in oil fields to enhance or improve the recovery of crude oil from the reservoirs. It works by increasing the viscosity of the injected water, thus improving its mobility and oil recovery. However, during such enhanced oil recovery (EOR) operations, it also produces a huge quantity of water alongside oil. Depending on the age and the stage of the oil reserve, the oil field produces ~ 7–10 times more water than oil. Such water contains various types of toxic components, such as traces of crude oil, heavy metals, and different types of chemicals (used during EOR operations such as HPAM). Thus, a huge quantity of HPAM containing produced water generated worldwide requires proper treatment and usage. The possible toxicity of HPAM is still ambiguous, but its natural decomposition product, acrylamide, threatens humans’ health and ecological environments. Therefore, the main challenge is the removal or degradation of HPAM in an environmentally safe manner from the produced water before proper disposal. Several chemical and thermal techniques are employed for the removal of HPAM, but they are not so environmentally friendly and somewhat expensive. Among different types of treatments, biodegradation with the aid of individual or mixed microbes (as biofilms) is touted to be an efficient and environmentally friendly way to solve the problem without harmful side effects. Many researchers have explored and reported the potential of such bioremediation technology with a variable removal efficiency of HPAM from the oil field produced water, both in lab scale and field scale studies. The current review is in line with United Nations Sustainability Goals, related to water security–UNSDG 6. It highlights the scale of such HPAM-based EOR applications, the challenge of produced water treatment, current possible solutions, and future possibilities to reuse such treated water sources for other applications.

Acrylamide‐sodium acrylate copolymers: A comparison between copolymerization and hydrolysis

“…The use of pushing fluids, injected several kilometres from a well, can improve oil recovery by several percent. The water use can be 7–10 times higher than the oil recovered, as is a function of the age of the reservoir [ 14 ] ; despite this half, the oil can remain underground and unrecovered. While secondary tertiary recovery involving the injection of water or gases to increase the pressure is usually carried out, tertiary recovery such as with polymer solutions can only be warranted depending on the current prices of the commodity.…”

Stability and Rheological Properties of the Hydroxypropyl Methyl Cellulose-Based Graft Copolymer/Halocynthia roretzi Drasche-Based Cellulose Nanocrystal/Sodium Dodecyl Sulfate Dispersion for Enhanced Heavy Oil Recovery

“…Polyacrylamide (PAM)-based displacement is one of the most widely utilized polymer flooding agents in tertiary oil recovery . In aqueous solution, PAM tends to hydrolyze and transform into partially hydrolyzed polyacrylamide (HPAM) with abundant carboxyl groups, which can lead to the viscosity enhancement of displacing fluid. , However, the practical application of PAM-based polymers is obstructed in reservoirs with harsh conditions (high temperature, high salinity, pressure, and bacteria), because PAM-based polymers usually degrade and hydrolyze in high-temperature and high-salinity conditions, leading to the destruction of the network structure and the production of a toxic acrylamide monomer. , Moreover, carboxylate groups incline to interact with metal ions, generate precipitation in the formation water, and in turn, cause viscosity reduction and recovery efficiency diminishment. − Therefore, various methods, such as the introduction of different functional groups, such as hydrophobic groups, − have been used to improve the chemical stability and temperature/salt tolerance of PAM-based polymers. In addition, natural polymers, such as cyclodextrin, xanthan gum, and chitosan, contain a rigid structure, which plays a significant role in thermostability enhancement, thereby improving oil recovery efficiency. , Therefore, we synthesized a kind of graft copolymer named PHAD using hydroxypropyl methyl cellulose (HPMC) containing a rigid six-membered heterocyclic structure, which had a relatively superior temperature and salinity resistance performance in hard reservoir conditions …”

Statistical and rheological evaluation of the effect of salts in partially hydrolyzed polyacrylamide solutions

“…Partially hydrolyzed polyacrylamide (PHPA) is the most used anionic synthetic copolymer for this application 5 . In addition to being versatile and with the possibility of structural modifications for specific applications, it has a low cost of application, high molecular weight, and solubility in aqueous media 6,7 …”