Novel Sensing

EESA researchers have shown that existing, unused telecommunication cables–known as ‘dark fiber’ networks–can be repurposed as arrays to acquire seismic data at unprecedented spatial and temporal resolutions along distances of several tens of kilometers. Distributed Acoustic Sensing (DAS) systems on dark fiber networks have been successfully deployed by EESA in a variety of applications, such as acquisition of ambient seismic noise for shear-wave velocity imaging and detection of both teleseismic and regional earthquakes. They have even transferred these technologies to the ocean floor, where dark fiber networks abound. These demonstrations showcase the tremendous potential of this new technology in seismological investigations with applications that range from earthquake detection to geotechnical characterization, reservoir imaging, groundwater monitoring, and subsurface process characterization, among many others.

Example project: Imperial Valley

EESA researchers are developing distributed fiber optic sensing (DFOS) technologies for energy, environmental, and civil infrastructure sensing and monitoring. Utilizing Brillouin, Rayleigh, and Raman backscattering signals associated with temperature and strain changes, DFOS provides unprecedented data density and spatial coverage uniquely suited for large infrastructure operation, security, and emergency management applications. Examples of ongoing research include offshore wind-turbine monitoring and impacts on large marine mammals such as humpback and gray whales; underground natural gas storage safety monitoring, and pipeline safety monitoring.

CASSM was developed to provide real-time, continuous data on reservoir dynamics and to enable detection of reservoir trends that would otherwise go unrecorded by intermittent monitoring. CASSM is a combination of experimental methodology, surveying geometry, and instrumentation developed and built at the GMF. For it to be successful, the CASSM approach required a seismic source which could be deployed on the outside of standard production tubing within the tight quarters of an underground observation well. At GMF, researchers designed a hollow tube source from piezoelectric material with an offset center that slides onto the production tubing and can be clamped in place in the borehole for the duration of the seismic monitoring.

The Unmanned Aerial Vehicle (UAV)-mounted passive ElectroMagnetic (EM) platform under development, including sensor hardware and software with data treatment of time-lapse 3D images, will be used for Radio-MagnetoTelluric (RMT) or far-field controlled source EM surveys. The platform includes a lightweight and cost-effective EM sensor with a fast and integrated signal acquisition and treatment algorithm and an orientation and positioning system. The system will be pulled by a ground- or aerial-based vehicle with a user-friendly interface for data collection and processing tasks.

The Distributed Temperature Profiling (DTP) system involves a network of vertically resolved temperature probes (more than 10 sensors/probe) with an accompanying data acquisition system to autonomously sense temperature at numerous depths and locations. The DTP system has an extraordinarily low production and assembly cost. It uses automated data acquisition, management, and transfer through a miniaturized logger with integrated Bluetooth; enables data visualization through an app, storage, and web interface; and leverages and provides open source software and hardware to encourage community-based development and deployment. The current DTP system, based on our early system prototype, is produced in large batches (hundreds of units) and  deployed across field sites linked to various projects including NGEE-Arctic, Watershed Function SFA, and other projects where improving the quantification of hydro-thermal regimes is critical. This development represents a new paradigm in improving spatial coverage and resolution in identification of thermal regimes in the subsurface and in estimation of snow thickness and diffusivity, fraction of soil components, and heat and water fluxes.

TERI is a minimally invasive method that measures active roots and plant root traits such as total root mass and root distribution. These properties, which govern water and nutrient uptake and influence plant productivity, have been notoriously difficult to measure with existing invasive and labor-intensive methods. Using the plant as an efficient conductor, TERI measures electrical response at the ground surface as low voltage current is injected directly into the plant, providing information about plant roots and their traits. TERI can accelerate root-focused cultivar development by screening for selected root traits for the correlation between TERI electrical signals and total root mass and active root-water uptake zone measurements.

Plants as Sensors (YouTube video)

EESA scientists have developed a prototype of the SMART (Sensor at Multi-scales with Autonomous Remote Telemetry) Soils testbed. The SMART Soils testbed establishes a core capability for controlled soil ecosystem studies at mesoscales, integrating novel sensing approaches across scales with advanced data capabilities, and linking lab and field experiments. This mesoscale-fabricated ecosystem is designed to support multiple DOE-BER objectives by enabling interrogation of biological-environmental interactions across molecular to field-relevant scales under controlled conditions. With the capacity to control and manipulate hydro-biogeochemical conditions, the SMART Soils testbed provides a model system to deconvolve complex and interdependent variables that are challenging to decipher at field scales. The lab-field connectivity of the testbed provides the capacity for interactive control and feedback between parallel experiments at both scales. Developing capabilities are described here.