Polymeric gels have been an important category for material scientists due its versatile structural features. Hence, hydrogels are being used to reduce excess production water in oil reservoirs. In this work, cross-linked partially hydrolyzed polyacrylamide (HPAM) composite hydrogels impregnated with bentonite clay (Bent) and bentonite clay modified (Orgbentent) with the surfactant hexadecyltrimethylammonium bromide were synthesized and characterized as a sealing agent in high water producing permeable zones in the petroleum industry. The concept of utilizing hydrophobically modified clay as an inorganic additive in the hydrogel matrix emanates from the fact that this additive exhibit greater interaction with the polymer chains. These interactions can promote the inherent properties of the hydrogel. Polyethyleneimine (PEI) was chosen as the cross-linking agent. HPAM/PEI conventional hydrogels and HPAM/PEI/Bent and HPAM/PEI/Orgbent at 100 mg•L −1 clay were synthesized. The developed hydrogels were characterized by a hybrid rheometer and Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA) instruments. Rheological results reveal that the (HPAM/PEI/Bent-3 and HPAM/PEI/Orgbent-3) composite hydrogels showed higher elastic modulus (G′) and durability in the studied conditions (stable at 30 days) than conventional ones (HPAM/PEI), indicating the dispersion and reinforcing effect of clay. The functional groups of these hydrogels were confirmed by FTIR, and TGA demonstrated the structural reinforcement due to the presence of the clays, which had lower weight loss than the conventional hydrogel. The hydrogel morphologies were analyzed by SEM, and the results corroborated with those obtained by TGA, indicating better structural reinforcement when using organophilic clay.
In fractured reservoirs, fluids injected Enhanced Oil Recovery (EOR) are channeled through the fracture zones and travel through highly permeable regions, failing to displace part of the oil, and decreasing oil recovery efficiency. To solve these problems, the conformance control technique is now widely used, as it allows the reservoir to be swept totally, similar to the ideal condition. In this context, polyacrylamide-based polymer gel systems can be used to block the high-permeability regions of the rock matrix, forming in situ hydrogels that block the rock pores, avoiding the channeling of the fluids, and increasing the oil production. These polyacrylamide-based hydrogels can be crosslinked by inorganic (metal ions) or organic substances, and various systems are used for conformance control. Due to the greater stability of the bond formed between the polymer and the organic crosslinker, these systems are now used in higher temperature reservoirs. In order to produce hydrogels with higher resistance to severe salinity and temperature conditions, nanoparticles are applied to form systems with good mechanical resistance, and high thermal stability. These have presented promising results for conformance control.
Due to the growing demand for oil and the large number of mature oil fields, Enhanced Oil Recovery (EOR) techniques are increasingly used to increase the oil recovery factor. Among the chemical methods, the use of polymers stands out to increase the viscosity of the injection fluid and harmonize the advance of this fluid in the reservoir to provide greater sweep efficiency. Synthetic polymers based on acrylamide are widely used for EOR, with Partially Hydrolyzed Polyacrylamide (PHPA) being used the most. However, this polymer has low stability under harsh reservoir conditions (High Temperature and Salinity – HTHS). In order to improve the sweep efficiency of polymeric fluids under these conditions, Hydrophobically Modified Associative Polymers (HMAPs) and Thermo-Viscosifying Polymers (TVPs) are being developed. HMAPs contain small amounts of hydrophobic groups in their water-soluble polymeric chains, and above the Critical Association Concentration (CAC), form hydrophobic microdomains that increase the viscosity of the polymer solution. TVPs contain blocks or thermosensitive grafts that self-assemble and form microdomains, substantially increasing the solution’s viscosity. The performance of these systems is strongly influenced by the chemical group inserted in their structures, polymer concentration, salinity and temperature, among other factors. Furthermore, the application of nanoparticles is being investigated to improve the performance of injection polymers applied in EOR. In general, these systems have excellent thermal stability and salinity tolerance along with high viscosity, and therefore increase the oil recovery factor. Thus, these systems can be considered promising agents for enhanced oil recovery applications under harsh conditions, such as high salinity and temperature. Moreover, stands out the use of genetic programming and artificial intelligence to estimate important parameters for reservoir engineering, process improvement, and optimize polymer flooding in enhanced oil recovery.
Polímeros reticuladospodem sofrer modificações tornando-os capazes de capturar substâncias presentes em um meio reacional líquido. Neste trabalho,realizou-se uma polimerização em suspensão com os monômeros acrilato de etila e divinilbenzeno, magnetizado pela incorporação de maghemita in situ. O reagente polimérico acil-hidrazida magnetizado foi obtido pela reação com hidrato de hidrazina. A caracterização foi realizada por técnicas de espectroscopia no infravermelho, fluorescência de raios x, ensaios de força magnética e microscopia eletrônica de varredura
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