At present, one of the main problems existing in deep oil and gas reservoirs is of high heterogeneity, so shielding temporarily plugging technology is indispensable to protect the permeability. From this point of view, the appropriate plugging agent is the critical material which requires to possess the functions of both temporary plugging and easily plug removal for oil wells through the degradable process as well as environment friendly. In this work, degradable copolyester nanocomposites which were served as the temporary plugging agent were successfully synthesized with lactic acid, terephthalic acid, ethylene glycol monomers and nano SiO2 by the polymerization method, including the synthesis process of the carboxyl terminated l-lactic acid prepolymer (PLLA) and the polymerization process of bis-(2-hydroxyethyl terephthalate) (BHET) with PLLA in the presence of nano SiO2. Notably, the results indicated that the degradable nanocomposites were prepared during polymerization, accompanied with a homogeneous dispersion of nano SiO2 in the matrix, as demonstrated by FTIR and TEM. With the addition of nano SiO2, the molecular weight of the polymer from viscosity measurements was increased effectively. The thermal properties and mechanical properties were enhanced owing to better filler dispersion in the polymer. Furthermore, the degradation of the prepared composites in reservoir simulation environments was also evaluated by weight loss and SEM. The results exhibited that nanocomposites could be efficiently degraded in comparison with pure matrix. In particular, pilot test of the temporary plugging agent was carried out, which showed that their plugging rate was 82.25% and 35.78%, respectively before and after the degradation at designed time. The findings indicate that the degradable copolyester nanocomposites apply to protect oil and gas formation, which make them become the candidate materials to enhance oil recovery in eco-friendly petroleum engineering. Keywords: Degradable; Nanocomposite; Environment friendly; Temporarily plugging; petroleum engineering Founding The authors acknowledge financial support from the National Major Project (Grant: 2011ZX05009-005), National Natural Science Foundation of China (Grant: No. 51274223, Major Program, Grant: No.51490650), Innovation Fund of China National Petroleum Corporation (2014D-5006-0214), Science Foundation of China University of Petroleum, Beijing (No. KYJJ2012-06-30).

Synthesis and characterization of degradable nanocomposites based on poly(ethylene terephthalate)-poly(lactic acid) and functionalized SiO2

251st National Meeting (2016)

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