In the heart of China’s Xinjiang region, a groundbreaking technology is revolutionizing the way we monitor carbon dioxide (CO2) injection wells, a critical component in the global effort to mitigate climate change. Sen Chen, a leading researcher at the Engineering Technology Research Institute of Xinjiang Oilfield Company, has developed a novel approach using distributed optical fiber sensors to ensure the integrity of CO2 injection wells in real-time. This innovation, published in the journal Petroleum Exploration and Development, holds significant promise for enhancing the safety and efficiency of carbon capture, utilization, and storage (CCUS) projects worldwide.
CO2 injection wells are essential for both underground storage and enhanced oil recovery (EOR) processes. However, these wells face unique challenges, particularly corrosion from carbonic acid formed when CO2 dissolves in water. Traditional monitoring methods often fall short in detecting leaks and ensuring wellbore integrity. Chen’s research addresses these issues head-on by employing distributed optical fiber temperature sensing (DTS) and acoustic sensing (DAS) systems.
“The integrity of the wellbore is paramount for the safety and success of CO2 storage projects,” Chen explains. “Our technology provides a more accurate and reliable way to monitor these wells, ensuring that any leaks or issues are detected and addressed promptly.”
The distributed optical fiber sensors offer several advantages over conventional logging methods. They provide better performance indicators, higher temperature accuracy, and improved sensitivity and signal-to-noise ratio. This is particularly crucial in the complex conditions of CO2 injection wells. By analyzing variations in temperature and vibration caused by annulus pressure relief or gas injection, the system can differentiate between leakage signals and normal fluid flow signals.
One of the key innovations in Chen’s work is the use of a translation invariant wavelet algorithm for denoising DTS data. This method overcomes the limitations of traditional wavelet threshold algorithms, such as excessive smoothing and the pseudo-Gibbs phenomenon, ensuring more precise and reliable data.
The technology was put to the test in a field experiment involving a 1671-meter well. By installing 1631 meters of optical cable in the tubing, Chen and his team successfully identified the leakage position through gas injection and annulus pressure relief. The results demonstrated the accuracy and effectiveness of the distributed optical fiber sensing technology in real-time monitoring of gas injection string integrity.
The implications of this research are far-reaching. As the energy sector continues to explore CCUS as a viable solution for reducing carbon emissions, ensuring the safety and integrity of CO2 injection wells becomes increasingly important. Chen’s technology offers a robust and reliable solution, paving the way for more efficient and secure CO2 storage and EOR processes.
“This technology has the potential to significantly enhance the safety and efficiency of CO2 injection wells, making CCUS a more viable option for reducing carbon emissions,” Chen notes. “It’s a game-changer for the energy sector, offering a more accurate and reliable way to monitor these critical wells.”
As the world seeks sustainable energy solutions, innovations like Chen’s distributed optical fiber sensing technology will play a pivotal role in shaping the future of the energy sector. By ensuring the integrity of CO2 injection wells, this technology not only enhances safety but also contributes to the global effort to mitigate climate change. The research, published in Petroleum Exploration and Development, marks a significant step forward in the quest for more sustainable and efficient energy practices.
