Quantifying Oil and Gas Industry Related Geohazard Using Radar Interferometry and Hydro-geomechanical Modeling

The Permian Basin, containing a large amount of oil and gas, has been intensively developed for hydrocarbon production. However, the hazards related to the oil and gas industry including surface deformation and the underlying mechanisms in this region have not been well known. My PhD study aims to monitor the geohazards in the Permian Basin and better comprehend the subsurface mechanisms with the aid of high-resolution and high-accuracy Interferometric Synthetic Aperture Radar (InSAR) images. Generally, as the pore pressure is influenced by wastewater injection/hydrocarbon production, the pressure changes can propagate to other surrounding underground and overlying rock/soil layers, resulting in surface deformation. The distribution and temporal development of the surface deformation can be obtained from InSAR processing and analysis. To reveal the underground geo-mechanical process responsible for the development of the surface deformation, numerical modeling based on poroelasticity is then applied to estimate the effective parameters (i.e., parameters inferred from the simulation) including depth and volume. This method is applied to three cases in West Texas. At a site in Reeves county, InSAR detects surface uplift up to 17 cm near a wastewater disposal well from 2007 to 2011. Results from both elastic and poroelastic models indicate that the effective injection depth is much shallower than reported. The most reasonable explanation is that the well was experiencing leakage due to casing failures and/or sealing problem(s). At a site in Winkler county, surface uplift and the follow-on recovery detected by InSAR from 2015 to 2020 can be attributed to nearby wastewater disposal. Bayesian inversion with the poroelastic models provides estimates of the local hydro-geomechanical parameters. The posterior distribution of subsurface effective volumes reveals under-reported volumes in the well near the deformation center. We also investigate a case of aseismic slip related to oil and gas activities. The combination of InSAR observation and poroelastic finite element models in three cases shows the capability to investigate the ongoing geohazards related to fluid injection and hydrocarbon production in the Permian Basin. This kind of study will be helpful to the decision-making of federal/local authorities to avoid future geohazards related to oil and gas activities

Surface Deformation and Seismicity Linked to Fluid Injection in the Raton Basin

It is suggested that deep fluid injection may cause surface uplift and subsidence in oil and gas producing regions in addition to seismicity. This study uses the Raton Basin as an example to investigate the hydromechanical processes of surface uplift and subsidence following fluid injection and relate them to the region's seismic history. The Raton Basin, in southern central Colorado and northern central New Mexico, has experienced wastewater injection related to coalbed methane and gas production starting in 1994 and increased seismicity since 2001. In this study, we estimate the extent and magnitude of total vertical deformation in the Raton Basin from 1994 to 2020, and short-term deformation between the years 2017 to 2020 following a sharp decline in injection rates. Most modeled uplift between 1994 and 2020 occurred near the southern wells, where the greatest cumulative volume of wastewater was injected. However, modeled subsidence occurred around the southern and eastern wells between 2017 and 2020, after the rate of injection decreased. This shows that while the magnitude of uplift corresponds to cumulative injection volume and maximum rate in the long-term, short-term incremental deformation (uplift or subsidence) is controlled by changes in the rate of injection. The increased number of yearly earthquake events follow periods of modeled rapid uplifting throughout the basin, suggesting that surface deformation is caused by the same injection induced pore pressure perturbations that initiate seismicity.</p

SBAS Analysis of Induced Ground Surface Deformation from Wastewater Injection in East Central Oklahoma, USA

The state of Oklahoma has experienced a dramatic increase in the amount of measurable seismic activities over the last decade. The needs of a petroleum-driven world have led to increased production utilizing various technologies to reach energy reserves locked in tight formations and stimulate end-of-life wells, creating significant amounts of undesirable wastewater ultimately injected underground for disposal. Using Phased Array L-band Synthetic Aperture Radar (PALSAR) data, we performed a differential Synthetic Aperture Radar Interferometry (InSAR) technique referred to as the Small BAseline Subset (SBAS)-based analysis over east central Oklahoma to identify ground surface deformation with respect to the location of wastewater injection wells for the period of December 2006 to January 2011. Our results show broad spatial correlation between SBAS-derived deformation and the locations of injection wells. We also observed significant uplift over Cushing, Oklahoma, the largest above ground crude oil storage facility in the world, and a key hub of the Keystone Pipeline. This finding has significant implications for the oil and gas industry due to its close proximity to the zones of increased seismicity attributed to wastewater injection. Results southeast of Drumright, Oklahoma represent an excellent example of the potential of InSAR, identifying a fault bordered by an area of subduction to the west and uplift to the east. This differentiated movement along the fault may help explain the lack of any seismic activity in this area, despite the large number of wells and high volume of fluid injected

Mechanisms and Mitigation of Injection-Induced Earthquakes

Injection-induced seismicity caused by wastewater injection is a continuing problem for the central and eastern United States. Mitigation of induced earthquakes often focuses on operational parameters like injection rate. While pore pressure increase has been the main mechanism invoked in injection-induced seismicity, other mechanisms like Coulomb static stress transfer may play a role. In this dissertation, I examine the mechanisms of injection –induced earthquakes in relation to mitigation.I investigate the role of aggregate injection rate, the combined injection rate of multiple wells, by modeling pore pressure increase caused by 22 wastewater disposal wells injecting into the same disposal zone within 30 km of seismicity in Greeley, Colorado. I find that the wells 15 – 30 km from the seismicity contribute approximately 44% of pore pressure increase at the location of the earthquakes. Therefore, aggregate injection rate and well spacing is important when planning mitigation strategies. I also derive a simple relation between pore pressure change and surface deformation that can be used to constrain hydraulic parameters of confined aquifers to a first-order. This relation can estimate expected surface deformation associated with pore pressure model results, which can then be compared to observed surface deformation using geodetic techniques. I validate this relation by constraining the storativity of an aquifer in Texas that experienced uplift associated with wastewater disposal.Finally, I investigate the role of small magnitude earthquakes in induced seismicity. I use generic models to test if small magnitude earthquakes can cumulatively transfer, through earthquake interactions, stress of a magnitude comparable to pore pressure increase from wastewater injection. I find that the stress caused by earthquake interactions (Coulomb static stress transfer) is comparable in magnitude to pore pressure increase. However, the area influenced by the increased stress is much smaller than in pore pressure diffusion. This means that earthquake interactions may induce more earthquakes though over a smaller area than pore pressure increase. If earthquake interactions induce additional events, reduction in injection rate or even shutting down a well may not mitigate seismicity. Therefore, earthquake interactions should be taken into account when planning mitigation, especially the timing of mitigation measures

ALOS-2/PALSAR-2 Calibration, Validation, Science and Applications

Twelve edited original papers on the latest and state-of-art results of topics ranging from calibration, validation, and science to a wide range of applications using ALOS-2/PALSAR-2. We hope you will find them useful for your future research