The U.S. Department of Energy’s NETL and its partner organizations successfully developed and demonstrated a suite of embedded sensor technologies enabled with sensing materials for subsurface wellbore integrity monitoring — technology that can help realize effective geologic carbon storage, hydrogen storage and geothermal projects and reduce the wellbore integrity risks.

In response to needs identified within the Subsurface Science, Technology, Engineering, and Research and Development (SubTER) crosscut initiative, the team performed an integrated research and development effort to create a suite of complementary, multi-functional embedded sensor technologies for real-time subsurface monitoring of wellbore integrity, with emphasis on pH and corrosion monitoring of cement and casing steels. Cement and casing steel are the wellbore structural components.

With NETL leading project, several partner organizations lent their expertise in developing the sensors since the work began in April 2018—Illinois State Geological Survey, Intelligent Optical Systems, University of California at Los Angeles, University of Pittsburgh and Carnegie Mellon University.

“This collaboration spanning academia, industry and the public sector to create such a versatile technology with so many applications are a shining example of what the Lab is all about,” said Ruishu Wright, research scientist and the lead principal investigator at NETL. “The efforts span fundamental studies and characterization at the laboratory scale and sensor validation in the field tests. This project has generated seven filed and issued patents, 22 published journal papers, 13 presentations and 27 conference papers, representing the breadth of knowledge gained during the work.”

Wellbore integrity is critical for success in geologic carbon storage, subsurface natural gas and hydrogen storage and enhanced geothermal systems to achieve the goals of safe and clean energy, environmental remediation and decarbonization. Wellbore integrity is the primary risk factor for these subsurface applications. Real-time and predictive monitoring of cement and casing steel can reduce the risks and support broad applications in subsurface.

In this project, thin film sensing layer and integration with sensor devices were pursued in parallel with device development and design efforts to enable the successful chemical sensing of three classes of devices, including optical fiber-based sensors (OFS), wireless surface acoustic wave sensors and wireless silicon integrated circuit sensors.

Development and demonstration of embedding sensors within representative wellbore materials was performed in this project, including the integration of OFS and wireless sensor devices into wellbore cement, as well as additive manufacturing-based techniques for embedding of OFS into representative casing steel. The team performed detailed characterization of sensor-infused wellbore materials to quantify and minimize impacts of embedding sensors into cement and casing steel.

NETL is a U.S. Department of Energy national laboratory that drives innovation and delivers technological solutions for an environmentally sustainable and prosperous energy future. By leveraging its world-class talent and research facilities, NETL is ensuring affordable, abundant and reliable energy that drives a robust economy and national security, while developing technologies to manage carbon across the full life cycle, enabling environmental sustainability for all Americans.