Numerical investigation of the influence of interaction between wellbore flow and lateral reservoir flow on CO2 geological sequestration

Abstract

A wellbore and a combined reservoir system are essential for the management of subsurface fluid resources and the geological storage of CO2. But the interaction between wellbore and reservoir flow is often neglected in studies of the combined system. A 2D radial model, considering the interaction of wellbore and reservoir flow was developed to investigate its impact on CO2 geological sequestration. The mass, energy and momentum equations for the wellbore and reservoir were solved using T2Well/ECO2N. The gas flow rate of the reservoir and wellbore are predicted, and the impact of interaction between wellbore and reservoir flow on the CO2 plume distribution and evolution was investigated. Furthermore, the influence of the CO2 injection rate, reservoir properties and salinity on the distribution of wellbore and reservoir flow was also explored. Interaction between the wellbore and reservoir flows determines the distribution of the reservoir gas flow rate which combined with layer thickness and porosity controls the horizontal distribution and evolution of the CO2 plume. The CO2 wellhead injection rate and reservoir properties (including lateral transmissivity, permeability) are vital factors influencing wellbore and reservoir flows. However, reservoir salinity has little effect on the interaction between the wellbore flow and the reservoir flow, but increased reservoir salinity can accelerate the horizontal migration of CO2. The results of this study may help to change the widely held opinion that the distribution of the injected CO2 among the individual layers is simply proportional to their transmissivity, and thereby enhance our understanding of CO2 evolution beneath the surface and provide theoretical support for safe and potential geological storage of CO2.