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Sustainability emphasizes the responsible use of finite resources on our planet, placing significant demands on the oil industry to use eco-friendly practices. One effective approach to reducing environmental impact is the use of green chemicals in upstream applications. The present work describes foaming properties investigation of a series of green in-house synthesized chitosan-based polymers (chitosan acetate S0 and hydrophobically modified reagents S1 and S2). These polymers were developed by grafting linear alkyl chains of varying lengths onto chitosan (–C5H11 to S1 and –C6H13 to S2), resulting in surface-active properties that enable them to reduce interfacial tension (IFT) and generate foams. The foaming properties of obtained polymers were investigated in order to study its applicability as agents for foam EOR.
To prove the interfacial activity of S-polymers, interfacial tension was measured at 25°C using n-decane as hydrocarbon phase through pendant drop method. The foaming properties of polymers were studied in bulk at ambient conditions, and in porous media under elevated pressure with three gases employed – air, N2 and CO2. All experiments were conducted in deionized water. First, the foaming ability of S0, S1 and S2 was tested in a home-made reactor that consists of a plastic transparent tube (100 cm height and 8 cm diameter) equipped with a 450-micron mesh on bottom for foam generation. Second, the foaming properties of polymers were tested in an HPHT microfluidic setup (80°C, 12 MPa). A borosilicate glass micromodel employed in this study contained random circular pore bodies connected with pore throats with the etching depth of 20 µm. The micromodel was fixed vertically in the holder, heated until target temperature (25 or 80°C) and filled with polymer solution with a gradual pressure increase. Foam was generated during simultaneous injection of aqueous phase and gas phase with equal injection rate of 50 µm. During the experiment, microfluidic system was pressurized with a high-pressure pump, and a heating jacket was used to maintain the temperature. A high-resolution camera was used to take time-lapse foam images. Images were analyzed with a customized code written on Python language (version 3.13.1).
It was found that after alkyl chains grafting chitosan-based polymers demonstrate interfacial properties. Thus, S1 and S2 reached IFT values of 34.76±0.28 mN/m and 28.10±0.23 mN/m in DI water, respectively. Preliminary testing of foaming properties at ambient pressure showed no foaming ability for S0, and a stable foam produced by S1 and S2 with air and nitrogen in neutral pH. Under high pressure, S2 demonstrated better foaming stability and longer half-life compared to S1. Same result was achieved in porous media regardless of gas type. Consequently, hydrophobically modified chitosans demonstrated strong foaming ability and can be further investigated as agents for gas/foam EOR.
| Country | Saudi Arabia |
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