Conducting safe and effective waste disposal and sequestration processes relies on an accurate determination of the reservoir extent and the prevailing boundary conditions. Due to the limitations surrounding the acquisition and analysis of the reservoir geometry, waste disposal, cuttings re-injection, and CO2 sequestration studies are based on simplifying assumptions regarding the lateral and vertical fluid flow boundary conditions. These assumptions can jeopardize the study’s outcomes, especially for green fields. Common boundary conditions considered are limited to either open (steady-state) or closed (semi-steady state) lateral boundaries, alongside a complete or partially sealing caprock. This study uses pressure transient analysis to provide a quantitative tool to assess a wider variety of fluid flow boundary conditions. We show that a short drawdown followed by a pro-longed buildup test can identify the fluid flow boundary condition, including closed, open, semi-open, and infinite systems. The significant difference in CO2 storage capacity and the different geomechanical risks associated with various fluid flow boundary conditions suggest that the presented methodology should be considered prior to fluid injection scenarios.
Geologic sequestration is an increasingly important strategy to dispose of drilling fluids, saltwater, and hazardous waste and to reduce the CO2 concentration in the atmosphere (Mortezaei et al., 2021). The most viable CO2 sequestration targets include deep saline aquifers and mature hydrocarbon fields (Garcia et al., 2010; Sarhosis et al., 2018; Bachu, 2003; Holloway, 2001; Holloway and Savage, 1993; Klara et al., 2003). The fluid flow boundary conditions of the target storage medium need to be known to predict the target formation’s storage capacity, the spreading of the injected plume, and the geomechanical risks associated with the pore pressure increase. The current practices commonly consider an assortment of simplified boundary conditions that include open and closed boundaries when it comes to sequestration.