Land Subsidence Monitoring in Azar Oil Field Based on Time Series Analysis

The Azar area is located in the east of Mehran in Ilam, Iran, is an arid region where oil extraction started form 2014. The subsidence is mainly observed in the vicinity of the oilfield. In this study we has measured the land subsidence in Azar oil field through a time series analysis. time-series interferometric synthetic aperture radar (T-InSAR) has emerged as a powerful technique to measure various surface deformation phenomena of the earth. The main step in all T-InSAR algorithms is the phase unwrapping step to resolve the inherent cycle ambiguities of interferometric phases and to estimate absolute deformation between pixels/points.T-InSAR was done to investigate what the corresponding subsidence source is. The Stanford Method for Persistent Scatterers (StaMPS) package was employed to process Envisat ASAR images collected between 2003 and 2009, as well as Sentinel-1A images collected between 2014 and 2018. The subsidence to have occurred with a mean rate up to 6 mm/year between 2014 and 2018, but no subsidence took place between 2003 and 2009 in the radar line of sight direction. Due to the high depth of oil wells (4,300 kilometres) we expect that the induced cover the large area and has a small magnitude.

The results of the study confirm pattern of subsidence induced by oil extraction. The results of this study also reveal that the factors leading to land subsidence include oil extraction, heavy rainfall, and poor soil condition. The analysis also show that oil extraction plays a key role in land subsidence in Azar oil field. Also the result of the InSAR cumulative map shows seasonal displacements on territory oilfield.