With the potential to become a sustainable clean energy source in the future, geothermal energy is usually produced from geothermal systems. To extract a considerable amount of heat from underground, deep wells are usually drilled to reach a high-temperature production zone. The temperature surrounding a deep geothermal well is usually much higher than that surrounding oil and gas wells. At such a high temperature, constituent polymers of seals used for zonal isolation in geothermal wells may undergo cracking, degradation, and decomposition. To address this challenge, this study aims to develop a novel nano-reinforcement approach to preparing thermally resistant polymer nanocomposites that are adequate for sealing deep geothermal wells. The surface properties of small-size lamellar graphite (SFG15) particles were treated to form a strong bond between graphite and the polymeric matrix. The X-ray photoelectron spectroscopy (XPS) analysis of treated graphite particles showed that carboxyl (-COOH) groups are formed on the surface of treated particles and their oxygen contents are considerable. The bonding of -COOH groups to the surface of graphite is stable at high temperatures. We prepared polymeric nanocomposites by adding various contents of surface-treated SFG15 particles to ethylene propylene diene monomer (EPDM). Scanning Electron Microscopy (SEM) images of EPDM-graphite nanocomposites revealed intercalation and uniform dispersion of treated graphite within the polymeric matrix. The addition of treated graphite to EPDM significantly improves its high-temperature mechanical resistance. As is shown by dynamic mechanical analysis of prepared nanocomposites, 9 wt% of treated graphite could improve the high-temperature storage/elastic modulus and loss/viscous modulus of EPDM rubber by around 200% and 140%, respectively. Considering the markedly improved mechanical resistance of developed nanocomposites at high temperatures, they are a promising candidate for the constituent polymer of seals applicable in geothermal wells.

Press the Back button in your browser, or search again.

Copyright 2024, Stanford Geothermal Program: Readers who download papers from this site should honor the copyright of the original authors and may not copy or distribute the work further without the permission of the original publisher.