A review of cement testing apparatus and methods under CO2 environment and their impact on well integrity prediction – Where do we stand?

In 1997 at Kyoto, Japan, world leaders agreed to reduce the carbon emission by innovating existing and implementing new technologies. During a conference meeting in Paris 2015, there was an eye opener to the way we see Carbon dioxide (CO2) emission. Up to date, new technologies have been developed to capture carbon dioxide and store them in underground formations such as aquifers or depleted gas or oil reservoirs. CO2 can also be re-injected into the reservoir for enhanced oil or gas recovery, but also possess a high wellbore density which requires much detail attention on long term wellbore integrity. It implies a new risk management challenge for drilling engineers: ensuring long-term well integrity, as the well system is susceptible to corrosion and leakage, especially on the cement side. As cement serves a physical barrier allowing seal fluid flow into unintended zones from the wellbore. The sealing effectiveness of cement reliant on insitu environment conditions and cement chemical compositions, inducing the time dependent stress geometry in the vicinity of the wellbores. Extensive experimental studies on oil well cement degradation behavior in the presence of CO2 or CO2-brine (saturated formation water) had been conducted by many researchers for many years. Having an upright understanding of CO2 on the cement integrity lifecycle is essential to expand the applications of CO2 sequestration or CO2 EOR activities. As new cementing products are continuously released on the market, their applicability requires intensive testing with respect to well integrity to avoid any potential CO2 leakage pathways. The testing cement recipes are based on a precise and repeatable mimicking of downhole conditions. A comprehensive literature review has shown that different testing methods are used worldwide with different results on the behavior of oil well cement in the presence of CO2 environment. Our study is trying to close the gap of unknown testing conditions and will provide a detailed documentation of the experimental setups worlwide. This paper presented a critical review of selected testing facilities, experimental methodologies and apparatus for different cement samplings as subjected to CO2 in recent years. Additionally, the long-term cement performance and its impact on well integrity was discussed. • The experimental studies of CO2 on cement integrity lifecycle are reviewed in this study. • Experimental testing facilities for different cement samplings as subjected to CO2 are surveyed. • Experimental methodologies and apparatus for cement integrity analysis under CO2 reservoir conditions are reviewed. • The long-term cement performance and its impact on well integrity under the impact of CO2 was discussed. [ABSTRACT FROM AUTHOR]