Comparative Analysis of CO2 Resistant Slurry Design and Conventional Oil Well Cement: The Inaugural Step towards Sustainable Energy Transition

Abstract With the growing urgency of global climate issues, reducing carbon dioxide emissions has become a crucial component of the sustainable energy transition. Innovative technologies are receiving increased focus, with Carbon Capture and Storage (CCS) emerging as a promising solution to mitigate the environmental impacts of fossil fuel consumption and industrial emissions. As nations strive to meet ambitious carbon reduction targets, the exploration of effective CCS applications becomes paramount. However, despite the potential of CCS, significant challenges persist in its widespread implementations due to limited information especially on long term wellbore integrity. This paper aims to offer insights and provide a comparative analysis on how cementing designs being the key to wellbore integrity and long-term zonal isolation will be affected when exposed to carbon dioxide (CO2). Extensive lab testing has been conducted comparing conventional API cement versus a CO2 resistant cement design that has been developed especially for wells with CO2 or CCS application for a period across one month. Both cementing designs were tested for mechanical properties, gas permeability, porosity, XRD and water analysis under non-CO2 exposure and CO2 exposure condition. Additional testing including thermogravimetric analysis (TGA), computed tomography (CT) scans and phenolphthalein testing were also performed on both the designs under CO2 exposure condition. To simulate the aging or extended exposure time of carbonic acid attack, acetic acid which is a stronger acid was chosen as the main acid catalyst to conduct solubility testing. Through the month-long period, extensive data sets were gathered through a series of lab testing, providing insightful comparison of a conventional API cement and CO2 resistant cement design after being exposed to CO2. Both qualitative and quantitative data has provided interesting evidence that the conventional API cement goes through a more severe carbonation (i.e., CO2 attack) as compared to a CO2 resistant cement design. Analysis on each of the testing and observations done through the suite of test that was conducted shall be presented in greater detail within this paper. As the energy industry navigates the imperative of reducing carbon footprints, the novel information presented in this paper aims to guide practitioners and researchers towards more effective and innovative cementing solutions. Ultimately, the incorporation of CO2 resistant cement slurry design signifies a pivotal step in fortifying wellbore integrity for CCS application.