Robust In-Situ Strain Measurements to Monitor CO2 Storage
The goal of this project was to develop and demonstrate robust instrumentation to monitor the in-situ strain tensor in order to improve the reliability and security of CO2 storage in geologic formations. We met the original goals of the project and the major overarching accomplishment is the advancement of strain tensor monitoring from an intriguing concept to a commercially available technology with a solid foundation of novel instruments supported by theoretical analyses and validation experiments. The main accomplishments of the project are summarized below. We designed, built and evaluated nine new optical fiber strainmeters and tiltmeters using Michelson interferometers to measure deformation with ultra-high resolution at both shallow and deep point locations in the subsurface. These are the robust strainmeters that motivated the title of the project. We designed, built and evaluated a novel method of measuring distributed strain in optical fibers with nanostrain resolution, and cm-scale location, and sampling into the seismic band. The new method is called Coherence-length-gated Microwave Photonics Interfereometry (CMPI). CMPI technology has advantages over existing commercial DAS and DSS methods. We developed and demonstrated capabilities to deploy instruments in the field and used them to measure strain caused by ambient signals like barometric pressure and tides, as well as induced signals like surface loading and pore pressure changes from pumping tests. We deployed a working strainmeter at 1,700 ft depth, slightly above an active reservoir. This is to our knowledge the greatest depth a strainmeter has been deployed and the techniques we used can readily be extended to greater depths. Optical fiber borehole tensor strainmeter techology was advanced from a TRL 4 at the start, to a TRL of 7 at the conclusion of the project. The project included advances in simulations and theoretical analyses. We developed and demonstrated a computational workflow that uses machine learning to reduce the computational requirements and make it practical to use Bayesian inversion to solve large numerical poroelastic analyses needed to interpret strain tensor field data. We evaluated the strain tensor fields and time series that would be caused by leaks of CO2 or other fluids from reservoirs. These simulations demonstrated that signals from leaks could be measured with instruments developed for the project, opening a potentially new method for ensuring storage security. We showed that strains in caprock can be used to estimate pressure in a reservoir. This avoids the need to drill monitoring wells into the reservoir, and it expands the capabilities of monitoring in the caprock. The project includes a derivation and application of a novel analytical solution to the strains in the vicinity of a pressurized poroelastic inclusion. This solution explains field data measured during injeciton tests at the North Avant Field, and it will simplify future interpretation of strain tensor data. The project included a broad range of experiments, and of the most significant is the characterization of the strain tensor at an array three strainmeters during six injection tests at the North Avant Field, Oklahoma. This demonstrated repeatability of the strain signal measured by the new instruments developed for the project, and it showed similarities between the strain signal at shallow depths and pressure in the underlying reservoir. We also demonstrated that useful strain data can be measured at reservoir depths. This confirms that strain tensor data can be measured throughout the caprock over a reservoir. The project demonstrated the feasibility of using the strain tensor and distributed strain measured in caprock during a variety of different well tests where the pumping rate was constant, sinusoidal and positive, or a periodic square wave with zero net rate. This further strengthens the validity of using strain data to characterize reservoirs and aquifers. We also demonstrated that strain caused be fluctuations of air pressure and water pressure in the vadose zone can be measured and interpreted, suggesting that high resolution distributed strain measurements hold promise for monitoring the vadose zone. The project partially supported nine graduate students in the Environmental Engineering, Hydrogeology, Electrical Engineering programs at Clemson University. The research was described in nine journal papers, 23 talks and conference abstracts. Additional journal papers are in preparation. A new company called Tensora was started to provide strainmeter technology for commercial applications.
- Research Organization:
- Clemson Univ., SC (United States)
- Sponsoring Organization:
- USDOE Office of Fossil Energy and Carbon Management (FECM)
- Contributing Organization:
- Grand Resources Inc.
- DOE Contract Number:
- FE0028292
- OSTI ID:
- 1997547
- Report Number(s):
- DOE-Clemson-28292; TRN: US2404820
- Resource Relation:
- Related Information: All raw data from this project (DE-FE0028292) and incoming data from ongoing research are publicly available through the Seismological Facility for the Advancement of Geoscience's Data Management Center (SAGE DMC). All data managed by Clemson University are aggregated through the International Federation of Digital Seismograph Networks (FDSN) Network Code 2J, which can be found through the following listing:DeWolf, S. and Murdoch, L. C. (2016). Clemson University Subsurface Deformation Monitoring Network, International Federation of Digital Seismograph Networks, Dataset/Seismic Network, http://www.fdsn.org/networks/detail/2J_2016/, DOI: 10.7914/SN/2J\_2016.Metadata (StationXML) and waveforms (miniSEED) can be found via the SAGE MetaData Aggregator at:http://ds.iris.edu/mda/2J/The Gladwin Tensor Strainmeter deployed in AVN2 is operated and maintained by the EarthScope Consortium (formerly UNAVCO), whose data are also made publicly available under the FDSN Network Code PB. Metadata (StationXML) and waveforms (miniSEED) can be found via the SAGE MetaData Aggregator at:http://ds.iris.edu/mda/PB/AVN2/PROCESSED DATAProcessed strain along with monitoring well pressures and injection pressure and rate data from the suite of 2022 injection tests can be found at the National Energy Technology Laboratory’s Energy Data Exchange (EDX) at:Lawrence C. Murdoch and Scott DeWolf, 9A Injection: July 26 thru November 21, 2022, 2023-08-21, https://edx.netl.doe.gov/dataset/9a-injection-july-26-thru-november-21-2022, DOI: 10.18141/1995730
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
42 ENGINEERING
58 GEOSCIENCES
54 ENVIRONMENTAL SCIENCES
01 COAL, LIGNITE, AND PEAT
02 PETROLEUM
03 NATURAL GAS
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
97 MATHEMATICS AND COMPUTING
Carbon Storage
Sequestration
Geomechanics
Strain
Strainmeter
Optical Fiber
Leak Detection
Reservoir Characterization
Monitoring
Carbon Management