With an average life span of 30-40 years, the cement around geothermal production wells eventually cracks over time. Because wells with cracked cement are vulnerable to leakage, reduced strength, and corrosion, it's important to repair them in a timely fashion. However, repairs can easily top $1.5 million.
Researchers at the U.S. Energy Department's Pacific Northwest National Laboratory (PNNL) developed cement that can heal itself when cracks occur. Using self-healing cement for geothermal wells would save geothermal plants millions of dollars and would reduce the amount of downtime necessary for repairs.
PNNL chemist Carlos Fernandez and his team discovered that by adding polymers they could create self-healing cement. Found in the human body and plant structures, these large, chain-like molecules work to hold substances together.
The team discovered by mixing in 5-20% of man-made polymers into typical cement before it is poured and cured, the cement can repair itself when cracks occur. PNNL’s research team has successfully proven this cement can repair itself in a few days, and they predict it has the potential to heal itself in a matter of hours. They also project that the cement will have the ability for continuous self-healing, meaning it can repair itself many times over and maintain the rheological and mechanical properties necessary for geothermal wells.