Preparation of AM/PF Microspheres and Investigation of the Temperature Resistance Mechanism

To solve the problem of rapid decline in crude oil production, polymer microspheres have been applied for petroleum reservoir enhanced oil recovery. However, conventional polymer microspheres exhibit inadequate resistance to temperature in high-temperature reservoirs. Microspheres with enhanced temperature resistance were synthesized via water-soluble phenolic resin (PF) and acrylamide (AM) monomers, employing <i>N</i>,<i>N</i>-methylene bis acrylamide as a cross-linking agent, Span-80 as an emulsifier, and potassium persulfate as an initiator. The inverse suspension polymerization method was adopted. The effects of the cross-linking ratio and the monomer ratio on the particle size are investigated, and the swelling behavior of microsphere is studied. The temperature resistance of AM/PF microspheres is investigated by IR, microscopy, and scanning electron microscopy. Results demonstrate that PF incorporation significantly enhances the microsphere temperature resistance. AM/PF microspheres withstand 150 days at 140 °C, fulfilling deep profile control requirements in high-temperature reservoirs. For AM/PF microspheres, the temperature resistance duration decreases with an extended PF reaction time. AM/PF microspheres exhibit gradual swelling, requiring approximately 10 days to achieve a swelling ratio of 34.25 at 140 °C. The degradation process of microspheres at high temperatures is discussed according to the microstructure variations of the microspheres at 140 °C. Double-cross-linked AM/PF particles facilitate improved application of deep profile control and flooding technology by petroleum engineers.