Multi-Temporal SAR Interferometry for Vertical Displacement Monitoring from Space of Tengiz Oil Reservoir Using SENTINEL-1 and COSMO-SKYMED Satellite Missions

This study focused on the quantitative assessment of the vertical displacement velocities retrieved using Sentinel-1 and Cosmo-SkyMed synthetic aperture radar images for the Tengiz oilfield. Tengiz oilfield was selected as a study area because of its historically reported continuous subsidence and limited up-to-date studies during recent years. The small baseline subset time-series technique was used for the interferometric processing of radar images acquired for the period of 2018-2020. The geospatial and statistical analyses allowed to determine the existing hotspots of the subsidence processes induced by oil extraction in the study area. Ground deformation measurements derived from the Sentinel-1 and COSMO-SkyMed satellite missions showed that the Tengiz oilfield continuously subsided during 2018-2020 with the maximum annual vertical displacement velocity around -77.4 mm/y and -71.5 mm/y, respectively. The vertical displacement velocities derived from the Sentinel-1 and the COSMO-SkyMed images showed a good statistical relationship with R(2 >=)0.73 and RMSE <= 3.68 mm. The cumulative vertical displacement derived from both satellites for the most subsiding location also showed a good statistical relationship with R-2 equal to 0.97 and RMSE = +/- 4.69. The observed relative differences of measurements by both satellites were acceptable to determine the ongoing vertical surface displacement processes in the study area. These studies demonstrated a practical novelty for the petroleum industry in terms of the comparative assessment of surface displacement measurements using time-series of medium-resolution Sentinel-1 and high-resolution COSMO-SkyMed radar images.

Automated summary

This study quantitatively assessed the vertical displacement velocities in Tengiz oilfield using Sentinel-1 and Cosmo-SkyMed synthetic aperture radar images. The study found that the oilfield experienced continuous subsidence during 2018-2020, and identified hotspots of subsidence induced by oil extraction. The results showed that the measurements derived from the Sentinel-1 and COSMO-SkyMed images had a good statistical relationship and could effectively determine the vertical surface displacement processes in the study area.