Review of wellbore flow modelling in CO2-bearing geothermal reservoirs

Abstract Geothermal energy is a reliable, environmentally friendly resource efficiently transformed to other energy forms without any storage. Therefore, it has taken the attention of many investors in recent years. The investments in developing new technological materials, tools, fluids and methods to obtain fluid and heat transfer from a geothermal reservoir open the way to increase the efficiency of the entire geothermal power generation cycle in the medium and long terms. The effectiveness of a geothermal production system is directly related to the sustainability of the reservoir and production wells. At this point, the presence of CO2 is crucial for the life of a geothermal well as it provides extra pressure and a lifting mechanism to geothermal fluids along the wellbore. Studies that compare the effect of CO2 in a geothermal reservoir are available in the literature. However, a comprehensive review study investigating the impact of water and CO2 interactions under dynamic wellbore flow conditions is missing. This study aims to be a reference guide to geothermal industry experts by performing a comprehensive literature review of studies about wellbore dynamics involving geothermal fluids' physical and thermodynamic behaviour during production and injection in the presence of CO2 along the wellbore. In this study, a detailed literature review about the theory, methodology, advantages and drawbacks, and the challenges of using CO2 in a geothermal system and the effects of having CO2/geothermal water interaction in the wellbore is given.