Simulation of the Near Field Physiochemical Impact of CO2 Leakage into Shallow Water in the North Sea

Abstract

This study involves developing a small scale two-fluid numerical model to simulate CO2 bubble leakage from potential storage sites, and to predict the plume dynamics and dissolution of the bubbles dispersed from the sediments into the water column and beyond with the resultant seawater pH change. Calibrating results to lab and in-situ experimental data, the model is applied for simulations of potential sub-seabed reservoir leakages in locations within the North Sea's shallow waters where carbon storage is being considered. The model consists of a sub-model that predicts the initial bubble size forming on the water basin and further sub models for mass and momentum exchange to the seawater. It is found that it is unlikely that bubbles smaller than 30mm diameter will reach the water surface and atmosphere when leaked from depths greater than 20m, and will fully dissolve in the waters creating pH changes of various concentrations dependent on the plume dynamics and ocean currents at the leakage sites.