Reservoir Dynamics of Large-Scale Injection: Lessons Learned from the Permian Basin
Katie Smye
Center for Injection and Seismicity Research
The University of Texas at Austin
Injection for permanent disposal is the preferred strategy to handle the tens of millions of barrels of water produced daily from unconventional reservoirs in the Permian Basin region and in many other onshore basins in the U.S. This now decade-long experiment provides an unrivaled opportunity to integrate subsurface and surface data to understand the reservoir dynamics of large-scale injection and the mechanics of induced seismicity and other injection-related challenges.
Permian Basin injection can be understood to occur in five different geologic systems: in shallow and deep reservoirs of the Midland and Delaware Basins, and in the Central Basin Platform. Deep injection is into carbonate rocks above crystalline basement and is equivalent to injection in the Fort Worth Basin, TX, and in other areas of the U.S. midcontinent including Oklahoma and Kansas. Basement-rooted faults mapped with well logs, 3D and 2D seismic data, and earthquake sequences, extend upward into the deep injection strata in these basins. Pressure and stress perturbations associated with deep injection are the cause of historically high rates of seismicity in these regions that had relatively little natural seismicity. However, insights into the causes of this seismicity resulted in recent changes in operational practices in the Permian Basin and a 50% decrease in the rate of earthquakes of magnitude 3.0 and above over the last year.
Injection into shallow reservoirs in the Delaware and Midland Basins, and into the Central Basin Platform, is associated with seismicity to a much lesser degree. However, increasing shallow injection to take up the water diverted away from deep injection has resulted in dynamic changes to the reservoir with impacts including surface uplift, drilling challenges through newly overpressured strata, well control issues, and surface flows or blowouts from older vertical wellbores. Geologic characterization of the shallow injection strata using outcrop and geophysical data allows for modeling of pore pressure changes from injection, and we show that reservoir pressure has increased by up to 40% in places. Assessment of the capacity of these system to accommodate pressure increases from injection provides valuable insight into the strata and regions where injection can occur safely while minimizing risk to the surface environment.
Biography
Dr. Katie Smye is a research associate professor at the University of Texas at Austin. She is the Principal Investigator for the Center for Injection and Seismicity Research (CISR), an industrial associates program conducting research on water injection capacity challenges with a focus on the Permian Basin region. She is primarily known for leading integrated research efforts across a range of disciplines including analysis and mitigation of induced seismicity, reservoir response to large-scale injection, and resource assessment.
Katie has a PhD in earth sciences from the University of Cambridge and bachelors degrees in geology and chemistry from the University of Oklahoma. She has authored or co-authored more than 30 peer-reviewed scientific publications, serves as an Associate Editor of AAPG Bulletin, plays an active role in convening and chairing conference sessions on induced seismicity and related topics, and seeks to communicate science to the public through media interviews and speaking engagements.
