Human induced surface deformation in Oklahoma - An International Collaboration (Part 2)

By Alessandro Novellino; Remote Sensing Geoscientist within the Earth and Planetary Observation and Monitoring team at the British Geological Survey

Read part 1 of Alessandro's blog here

Outside the University of Buffalo campus
Last week, thanks to the GERC’s Early Career Researchers Development Fund, I had the opportunity to work at the University of Buffalo, characterising the subsurface pore-pressure changes for the Woods County area (Oklahoma, USA). The latter represents a unique laboratory where wastewater injection, hydraulic fracturing and gas extraction activities have been taking place simultaneously for almost a decade. The analysis extends the previous study carried out on the superficial ground deformation characteristics and the patterns derived from Interferometric Synthetic Aperture Radar (InSAR); the results of which have been submitted to Geophysical Research Letters and are currently under review. The work is led by S. Grebby (University of Nottingham) and is co-authored by myself and other colleagues from Geomatic Ventures Limited (A. Sowter and D. Gee) and Virginia Tech (E. Gilliland and N. Ripepi).

With the essential support of E. Chaussard, assistant professor of Geophysics at the Department of Geology, I spent five days focussing on building a well-constrained 3D multiphase flow model for water, oil and gas. The model accounts for the oil and gas operational data, geological and hydrogeological data obtained from the US Geological Survey (USGS), Oklahoma Geological Survey, Oklahoma Corporate Commission, Oklahoma Corporate Board and published academic contributions.

The model employs the USGS numerical code MODFLOW and its related sub-packages as a basis for estimating the pore-pressure changes which occurred in the area during 2015-2017 as a result of subsurface processes. It is critical to understanding these changes. In comparison to previous works, we have the ability to compare and validate the modelled pore-pressure changes and conduct basin-wide characterization using space-derived ground deformation measurements obtained from InSAR.
Indeed, the main goals of the second part of the Oklahoma study are to:
  • Support and quantitatively integrate the main findings of previous research, stating that local human activities are the likely reason for the observed pore-pressure stresses and, ultimately, of the recent earthquake activity in the area.
  • Indicate whether or not the poro-elastic stresses can play a significant role in superficial ground motion and, if so, whether the main stresses are due to injection of pressurized liquid for stimulate gas production, gas extraction or wastewater disposal.

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