Abstract
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 R2≥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 R2 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.
Highlights
Tengiz oilfield is located at the coast of the Caspian Sea with low-lying wetlands
The present research compared the vertical displacements derived from the Sentinel-1 and COSMO-SkyMed radar images collected during 2018–2020 for the Tengiz oilfield
The vertical displacement velocities derived from the Sentinel-1 and COSMO-SkyMed images showed a good statistical relationship with R2 equal to 0.93, P-value < 0.05 and RMSE equal to ±2.86 for the Profile one and R2 equal to 0.73, P-value < 0.05 and RMSE equal to ±3.68 for Profile 2
Summary
Tengiz oilfield is located at the coast of the Caspian Sea with low-lying wetlands. The recent successful studies by (Bayramov et al, 2021, Grebby et al, 2019 and Orynbassarova 2019) proved that the Tengiz oilfield was under the impact of ground deformation processes induced by the petroleum and gas operational activities.Tengiz Oilfield Remote SurveillanceNowadays, industry significantly benefits from the ground deformation mapping as one of the important advancements for the surveillance programs of onshore oil and gas reservoirs. The recent successful studies by (Bayramov et al, 2021, Grebby et al, 2019 and Orynbassarova 2019) proved that the Tengiz oilfield was under the impact of ground deformation processes induced by the petroleum and gas operational activities. It is well known that the interferometric technologies were verified as effective for the measurement of the sensor-to-target line of sight projection of the ground deformation mapping of large onshore reservoirs rather than traditional in-situ measurements using geodetic tools (Zhou et al, 2006; Mirzaii et al, 2019; Bayramov et al, 2020a; Bayramov et al, 2020b; Bayramov et al, 2020c). Besides the Tengiz oilfield, other successful ground deformation studies which proved the effectiveness and quality of interferometric technologies had been performed for the Karazhanbas oilfield, the Karaganda Coal Basin and other petroleum and mining sites in Kazakhstan (Junisbekova et al, 2016; Mozer et al, 2017; Togaibekov 2020). In-situ geodetic measurements don’t provide the broad coverage of vertical displacements (Shi et al, 2019)
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