Spatial and temporal relationship between InSAR-derived subsidence and idle well fluid elevations in the Kern Front and Kern Oil Fields David de Guzman [1], David Shimabukuro [1], Michael J Stephens [2], Steven Skinner [1] [1] Department of Geology, State University, Sacramento, CA [2] U.S. Geological Survey, Sacramento, CA

USGS disclaimer: the information in this poster is preliminary, is subject to revision, and has not received final approval by the USGS Sentinel-1A/B Data: Results: Introduction: Kern Front (a) (b) ▪ Land subsidence occurs in areas of oil and gas production ▪ Previous studies have mapped the spatial extent of displacement ▪ Subsidence is caused by fluid extraction without complete replacement ▪ The relationship between subsidence and

fluid pressures has not been fully explored Note: Uncertainty in elevations caused by vertical datum ambiguity is less Figure 4: Sentinel-1A/B mission SAR images used for InSAR and Small Baseline Subset (SBAS) analysis. 45 than 1 meter. Figure 1: Interferometric Synthetic (Xu et al., 2001) SAR acquisitions between June 12, 2015 and April 16, 2020 were used to create 269 interferograms. (a) Aperture Radar (InSAR) observed Figure 7: Idle well fluid heights (2010 - 2016) mapped over InSAR derived Spatial and temporal relations between SAR data is seen with baseline distances of earlier data restricted to subsidence in the Lost Hills and deformation rates for (a) the and (b) the Kern River Oil 100 meters and pairs separated by no more than 300 days. Grey dots not connected by lines are SAR data Belridge Oil Fields between 11/5/95 Field. The lower fluid elevations are offset to the west of deformation in the that were not used. Dots connected by lines are SAR data pairs that were used in the analysis. All SAR and 2/17/96 (Xu et al. 2001). Kern Front Oil Field while they are co-located in the images used for analysis were aligned to a master image (red). There was high temporal density for coverage except between February 2017 and October 2017. (b) Temporal coverage of the stacked Analysis: Study Area: interferograms. Kern Front Kern River InSAR Deformation: Idle Oil Well Data:

Figure 8: Idle well fluid elevations (m) plotted against deformation rates (mm/year) in the (a) Kern Front Oil Field and (b) Kern River Oil Field. Least squares regressions Figure 2: Map of the study area located in the Figure 3: The relationship between the show a weak relationship in the Kern Front with an R-squared value of 0.058. The southern of California with volume of water produced, oil Kern River, however, shows much stronger relationship between idle well fluid oil fields outlined. Study locations include the produced, and water or steam injected heights and deformation rates with an R-squared value of 0.373. Kern Front and Kern River Oil Fields. between 1977 and 2016 for (a) Kern Front and between 1988 and 2018 for Figure 5: Line-of-sight deformation rates of the Kern Figure 6: Idle oil well fluid elevations (1988 -2016) Preliminary results: (b) Kern River (CalGEM, 2020a). River and Kern Front Oil Field derived from 269 mapped in the Kern Front and Kern River Oil Fields. Study Approach: stacked interferograms spanning June 12, 2015 to Higher fluid elevations can be seen in the ▪ Kern River deformation rates and idle oil well fluid elevation correlate for the April 16, 2020. Deformation contours are in 10 northeastern side of Kern River while the lowest period studied ▪ Use interferometric Synthetic Aperture Radar (InSAR) to map spatial mm/year increments. The Kern Front Oil Fields has fluid elevations are found in the central and western ▪ This relationship is not present in Kern Front. It is not clear why this is the case. patterns of deformation in oil fields LOS subsidence rates up to 50 mm/year on its eastern part of the Kern Front Oil Field. (CalGEM 2020b) ▪ Next steps are to compare spatial pattern of fluid balance (volume of injection – ▪ Observe spatial distribution of idle oil well fluid elevation data side, while Kern River Oil Field has LOS subsidence of volume of production) with InSAR-derived deformation and idle well fluid ▪ Compare InSAR-observed deformation with fluid elevations over similar time up to 20 mm/year in its southwest region. elevations. frames References: Xu, H., Dvorkin, J., & Nur, A. (2001). Linking oil production to surface subsidence from satellite radar interferometry. Geophysical research letters, 28(7), 1307-1310. This work was funded by the California State Water Resources Control Boards’ oil and gas Regional California Department of Conservation, (2020a). Oil and gas online data: Geologic Energy Management Division, accessed January 8, 2020, at: Monitoring Program through a cooperative agreement between the U.S. Geological Survey and California https://www.conservation.ca.gov/calgem/Online_Data/Pages/Index.aspx. State University-Sacramento. California Department of Conservation, (2020b). Idle oil well fluid elevations : Geologic Energy Management Division, https://www.conservation.ca.gov/calgem/idle_well