Monitoring of natural gas storage in salt cavities using SAR interferometry
Abstract
Even with a low storage capacity, natural gas storage reservoirs in salt cavities allow a high distribution flow rate in case of potential peak consumption. Ground surface above the reservoirs might undergo subsidence due to salt creep decreasing the storage capacity at depth. Local authorities impose monitoring of the surface displacements by geodetic measurements using primarily leveling method. Development of remote sensing methods such as radar interferometry offers possibilities to make regular and frequent repetition of measurements of induced surface movements above the reservoirs.
We present here a study of a natural gas reservoir belonging to Storengy (affiliate Engie, gas provider in France) and settled into deep cavities at 1500 m underneath the towns of Tersanne and Hauterives (France), whose exploitation started in 1970 and 2012, respectively. The surface monitoring with SAR interferometry techniques is carried out using the approaches of permanent scatterers and small-baselines subsets. The dataset encompasses C-band SAR images archives acquired by the ERS, Envisat and Sentinel-1 ESA satellites for the 1992-2018 period. In this agricultural region, the tracking of displacements is possible on well platforms above each cavity and on man-made installations above the whole operation. Our results show a slow subsidence signal (mean 4 mm/yr in line of sight) at Tersanne. Between 1992 and 2010, the mean LOS velocity of the subsidence decreases from 4.9 to 4.0 mm/yr. We show that transient surface movements are correlated over time with volume losses at depth. We include uncertainty estimates based on two analysis: the coherence value (which provides an uncertainty for each pixel) and the standard deviation of neighboring pixels phase values (that indicates if the movements of the adjacent pixels are coherent). On each well platform, we observe that these estimates are correlated by a ratio 2 (mean 2.3 and 4.6 mm, respectively). Our results highlight the performance of InSAR for monitoring natural gas reservoir-induced surface deformation by precisely determining spatial boundaries of the surface affected by slow-rate movements and following transient displacements with a time resolution not reachable with leveling surveys.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.G21C0567H
- Keywords:
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- 1299 General or miscellaneous;
- GEODESY AND GRAVITYDE: 4331 Disaster relief;
- NATURAL HAZARDSDE: 4335 Disaster management;
- NATURAL HAZARDSDE: 4343 Preparedness and planning;
- NATURAL HAZARDS