InSAR observation and poroelastic finite element modeling of injection-induced ground deformation in West Texas

Abstract:

Wastewater disposal into injection wells is the most common way to manage the produced water in hydrocarbon production. The wastewater should be deposited into deep geologic structures, but the increased pore pressure can propagate to overlying layers and then induce surface deformation. Interferometric Synthetic Aperture Radar (InSAR), an effective tool to map ground deformation with up to millimeter level precision and meter level resolution, is used to monitor the small-sized and small-magnitude injection-induced ground uplift in West Texas. Sentinel-1A/B imagery from late 2014 to early 2020 is processed to track the time-series deformation. Considering the low coherence and atmosphere artifacts, Persistent scatterer InSAR (PSInSAR) methods is applied to generate time-series surface deformation. To comprehend the underlying geomechanical process of the injection-induced ground uplift, a three-dimensional poroelastic finite element model considering rock parameters of underground layers is conducted using Defmod, a finite element code for modeling crustal deformation. The precise hydraulic properties of the formations, as key properties in the underlying fluid diffusion, can be solved by jointly inverting InSAR-derived time series deformation and injection records (injected volume and depth provided by Railroad Commission of Texas). If the inversion results cannot fit the InSAR observation, the effective injected volume and depth can be added into model parameters to be solved along with hydromechanical parameters to reconduct the inversion. These analyses can possibly help to reveal undesired aspects like inaccurate volume report and wastewater leakage.