| Title | Polymer-Treated Graphite Nanocomposite for Sealing Applications in Geothermal |
|---|---|
| Authors | Sai LIU, Arash DAHI TALEGHANI |
| Year | 2024 |
| Conference | Stanford Geothermal Workshop |
| Keywords | Polymeric nanocomposite, graphite, surface treatment, geothermal, zonal isolation |
| Abstract | 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. |