Quantitative Assessment of Vertical and Horizontal Deformations Derived by 3D and 2D Decompositions of InSAR Line-of-Sight Measurements to Supplement Industry Surveillance Programs in the Tengiz Oilfield (Kazakhstan)

Emil Bayramov,Yermukhan Zhuniskenov,Manfred Buchroithner,Martin Kada

doi:10.3390/rs13132579

Emil Bayramov, Yermukhan Zhuniskenov + Show 2 more

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https://doi.org/10.3390/rs13132579

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Abstract

This research focused on the quantitative assessment of the surface deformation velocities and rates and their natural and man-made controlling factors at Tengiz Oilfield in Kazakhstan using the Small Baseline Subset remote sensing technique followed by 3D and 2D decompositions and cosine corrections to derive vertical and horizontal movements from line-of-sight (LOS) measurements. In the present research we applied time-series of Sentinel-1 satellite images acquired during 2018–2020. All ground deformation derivatives showed the continuous subsidence at the Tengiz oilfield with increasing velocity. 3D and 2D decompositions of LOS measurements to vertical movement showed that the Tengiz Oil Field 2018–2020 continuously subsided with the maximum annual vertical deformation velocity around 70 mm. Based on the LOS measurements, the maximum annual subsiding velocity was observed to be 60 mm. Cosine corrections of LOS measurements to vertical movement, however, revealed a maximum annual vertical deformation velocity of 77 mm. The vertical deformation confirmed typical patterns of subsidence caused by oil extraction. Detected east-west and north-south horizontal movements at the Tengiz field clearly indicated that the study area crossed by seismic faults is affected by natural tectonic processes. The overall RMSE of 3D decomposed vertical deformation in relationship to LOS measurements and cosine corrections were in the range of 10–13 mm and 6–8 mm, correspondingly. The results of the present research will support operators of oil and gas fields and also other types of infrastructure to evaluate the actual differences of InSAR ground deformation measurements against the required standards and the precision of measurements depending on the operational needs, timeframes and availability of radar imagery.

Highlights

Tengiz is an oilfield located in NW Kazakhstan’s low-lying wetlands along the northeast shores of the Caspian Sea
Our research focused on the quantitative assessment of the surface deformation velocities and rates and their natural and man-made controlling factors at the Tengiz oilfield using Small Baseline Subset (SBAS) remote sensing and geostatistical interpolation techniques followed by 3D and 2D decompositions and cosine corrections to derive vertical and horizontal movements from LOS measurements
The annual average vertical deformation velocity in the LOS was observed to be in the range of −56.86–25.49 mm/y over the Tengiz field during 2018–2020 (Figure 4a) for Ascending track 1 (Path: 57, Frame: 148, Absolute Orbit: 30579), −60.3–29.26 mm/y (Figure 4b) for Ascending track 2 (Path: 159, Frame: 149, Absolute Orbit: 35931) and

Summary

Introduction

Tengiz is an oilfield located in NW Kazakhstan’s low-lying wetlands along the northeast shores of the Caspian Sea. Proved that Tengiz Field has been for some time under the long-term influence of subsidence induced by oil and gas production. Interferometric Synthetic Aperture Radar (InSAR) technology was verified as a more effective technology for the ground deformation monitoring of large oil and gas fields and their infrastructure rather than traditional geodetic measurements of single points [3,4,5,6]. Grebby et al [1] and Orynbassarova [2] examined ground deformation characteristics caused by oil and gas exploitation in this area for the period of 2004–2009 and 2016– Monitoring of ground deformation processes at oil and gas fields has several business values for industry since it is one of the critical input parameters for geohazard risk assessment, induced seismicity, geomechanics surveillance programs (reservoir stress, volumetric strain, fault reactivations and dislocation), site safety for fault or landslide reactivation, well failures, environmental assessment, reservoir modelling, enhanced oil recovery (EOR), oil and gas production.

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