critical pressure calculation

June 12, 2023


Dr. Hostetler will present “A Computational Modeling Approach to Critical Pressure Calculations for Class VI Area of Review Delineation” [Thursday, September 14, 10:30 – Noon, Session Class VI UIC] at the Groundwater Protection Council 2023 Annual Forum in Tampa.

Presentation Category:  Carbon Capture and Underground Storage

Subsurface pressure increases as supercritical carbon dioxide is injected into a deep saline reservoir beneath a confining zone.  If the pressure buildup is great enough, brine could be lifted upward from the injection zone through an inadequately plugged or abandoned well that penetrates the confining zone.  This could result in the endangerment of an underground source of drinking water (USDW).  A Class VI Injection Permit requires a delineation of the Area of Review (AoR). The AoR is the superposition of the area of the buoyant supercritical plume itself, together with the area over which the pressure front is large enough to potentially endanger a USDW through some conduit.  The USEPA Class VI Guidance offers several approaches to calculating critical pressure.  Some of these methods are based on concepts of changes in potential energy in artificial penetration and are very easy to implement.  Unfortunately, they are simplified models and are also very conservative.  The USEPA Guidance also allows for the computation of the critical pressure by computational modeling.  We present a computational modeling approach that is more mechanistic, explicitly addresses uncertainty, can be updated as additional testing and monitoring data become available, and provides a more authentic representation of the critical pressure and hence, the AoR.

Dr. Hostetler has nearly four decades of experience as a geochemist and hydrogeologist. His expertise focuses on subsurface multiphase flow modeling, groundwater flow and transport modeling, and reactive solute transport modeling.  Dr. Hostetler is an SCS Engineer’s Deep Well Initiative and Class VI Permit Team member.  Charles Hostetler has a BS in Geosciences and a Ph.D. in Planetary Sciences from the University of Arizona.


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Posted by Diane Samuels at 12:03 pm