J. Jain, D. McIntyre, C.L. Goueguel
National Energy Technology Laboratory,
Keywords: CO2 sequestration, laser, monitoring
Summary:The U.S. Department of Energy’s carbon capture and sequestration (CCS) program goals to reduce emissions of carbon dioxide (CO2) from anthropogenic sources will require great cost and effort. To ensure the success of the program it is important that the carbon dioxide that is injected underground for storage remains there (99% permanence over 1000 years). A number of carbon dioxide monitoring techniques have been employed since the inception of the CCS program. The methods range from the injection of tracers, micro-seismic monitoring techniques, satellite imaging, aerial monitoring with gas sensors, and various optical techniques. In spite of significant advancement in technology, the quantification of CO2 remains a challenge. In addition, there is a need for real-time and long-term monitoring techniques that can also address the leak detection threshold. Therefore, the current technology gap warrants development of new monitoring techniques that are affordable, robust, and easily distributable and deployable in many different locations of a carbon storage site to detect the CO2 leakage. The monitoring of carbon sequestration poses numerous challenges to the sensor community. The sub-surface environment is notoriously harsh, with large potential mechanical, thermal, and chemical stresses, making long-term stability and survival a challenge to any potential in situ monitoring method. Despite its comparative novelty, laser induced breakdown spectroscopy (LIBS) has been demonstrated as a promising technology for chemical monitoring of harsh environments and hard to reach places. LIBS has a real-time monitoring capability and can be used for the elemental and isotopic analysis of solid, liquid, and gas samples. The flexibility of the probe design and the use of fiber-optics has made LIBS particularly suited for remote measurements. This presentation will focus on developing LIBS instruments for downhole high-pressure, high-temperature brine experiments, where CO2 leakage could result in changes in the trace mineral composition of an aquifer. The requirements for downhole instrumentation— compact, robust, and simple—are similar to those in other areas, such as space-based science and sub-sea exploration. The progress in fabricating a compact, robust, and simple LIBS sensor and distribution of many laser spark sources across a wide area for widespread subsurface leak detection will be discussed.