Abstract

High molecular weight polyacrylamides are key components in oil recovery, particularly in the stimulation, production, and enhanced oil recovery of oil and gas wells. These polymers can be divided into three broad classes based on their physical state: dry polyacrylamides (DPAMs), emulsion polyacrylamides (EPAMs) and solution polyacrylamides (SPAMs). While the molecular weights of these polymers can range from 1 million to more than 30 million Daltons, molecular weight is limited by physical state. In general, EPAMs can reach higher molecular weights and consequently exhibit better performance than DPAMs and SPAMs. However, standard EPAMs exhibit poor freeze tolerance and irreversible inversions, while DPAMs suffer from extremely slow dissolution rates and require additional capital expenses such as makedown and storage equipment.

Next-generation winterized EPAMs have been developed that are capable of withstanding temperatures down to −35 °C without freezing. These polymers invert rapidly, reaching complete dissolution within 60 seconds in fresh water, hard water, and other concentrated brines, allowing for higher throughput and overall energy savings. The new EPAMs were compared to commercially available EPAMs used in friction reduction and EOR applications. The emulsion stability was assessed by freeze-thaw and rheological measurements, while stimulation and EOR performance were characterized using a friction loop and core flooding apparatuses. These next-gen EPAMs demonstrate values for viscosities, shear resistance, inversion times, freeze tolerance, and filterability that make them superior to commercially available dry and emulsion polyacrylamides. Furthermore, these polymers are formulated to be environmentally friendly and readily biodegradable.

A family of emulsion polymers has been developed that exhibits low-temperature tolerance, increased dissolution rates and biodegradability without sacrificing EOR and stimulation performance in various brines. The modular nature of these products has led to the creation of a flexible polymer platform that allows for customizing products for specific application needs.

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