Semianalytical solution for CO2 leakage through an abandoned well

Area of Science:

• Geological Engineering
• Environmental Science
• Earth Science

Background:

• Geological storage of carbon dioxide (CO2) is a key strategy for mitigating anthropogenic emissions.
• Existing oil and gas wells in mature sedimentary basins pose potential leakage pathways for injected CO2.
• Accurate modeling of CO2 leakage is essential for ensuring the long-term security of geological storage.

Purpose of the Study:

• To develop a semianalytical solution for predicting CO2 leakage rates and plume behavior.
• To analyze CO2 leakage through abandoned wells in deep geological formations.
• To provide an efficient tool for assessing the integrity of carbon capture and storage (CCS) sites.

Main Methods:

• Development of a novel semianalytical solution framework for CO2 injection and leakage modeling.
• Simulation of supercritical CO2 injection into a brine-saturated deep aquifer.
• Prediction of CO2 plume extent, leakage rates through abandoned wells, and plume migration in overlying aquifers.
• Validation of the semianalytical solution against a numerical multiphase flow simulator.

Main Results:

• The semianalytical solution accurately predicts CO2 plume extent and leakage rates, showing excellent agreement with numerical simulations.
• Calculations highlight the influence of outer boundary conditions, fluid property contrasts (density, viscosity), and local upconing.
• The model demonstrates the importance of considering well integrity in assessing the risks of CO2 geological storage.

Conclusions:

• The developed semianalytical solution offers a simple and efficient method for estimating CO2 leakage.
• This tool is valuable for risk assessment in geological CO2 storage projects involving injection and leaky wells.
• The findings underscore the need for careful site characterization and monitoring to prevent CO2 release.