## 1 Introduction  
The rapid escalation of anthropogenic CO\({}_{2}\) emissions, which reached 37.4 gigatons per year in 2023, has significantly contributed to global climate change [1]. This alarming rise in CO\({}_{2}\) emissions is predominantly fueled by the coal industry (41%), the oil industry (32%), and the gas industry (21%), with cement plants accounting for 4% and the remaining 2% from flaring and other miscellaneous sources. It was estimated that 44% of the emitted CO\({}_{2}\) remains in the atmosphere, and the remainder is absorbed by the oceans and the land ecosystem [2; 3; 4; 5; 6; 7]. The atmospheric concentration of CO\({}_{2}\) has consequently surged to approximately 424 ppm, a stark increase from the pre-industrial level of 278 ppm. This drastic rise in CO\({}_{2}\) levels has amplified global temperature anomalies, underscoring the urgency for effective mitigation strategies, such as CCS, to combat global warming. CCS has emerged as a viable solution, with over 43 operational CCS sites worldwide and projections indicating more than 290 projects in the United States by 2040 [1]. These sites are expected to store nearly 1 Gt CO\({}_{2}\) y\({}^{-1}\) in the subsurface [1]. However, the environmental challenges posed by orphaned and abandoned wells across the United States present significant risks to the integrity and success of CCS operations. The success of CCS depends on the ability to permanently store CO\({}_{2}\) in the subsurface and to monitor and minimize CO\({}_{2}\) leakage across decadal timescales. In this regard, the US has to contend with a unique challenge: CO\({}_{2}\) leakage pathways through the millions of abandoned and orphaned (A&O) oil and gas wells. Potential subsurface interaction between sequestration sites and A&O wells presents significant risks to the integrity and success of CCS operations. The location of the majority of these wells remains ambiguous, further complicating efforts to manage their impact. In the early days of the oil industry, the practice of plugging and abandonment was rudimentary at best [8]. When wells stop producing, operators often throw debris into the wellbore, with little consideration for proper sealing. Reports from the U.S. Environmental Protection Agency (EPA) in 1983 revealed that wells were merely plugged using wood, trees, or pieces of metal, and casing was often left or removed without proper sealing, particularly during World War II [9]. This lack of adequate cement barriers in many orphaned wells presents critical challenges to CO\({}_{2}\) storage efforts today, as these structures can serve as potential leakage pathways if CO\({}_{2}\) storage sites interact with them as shown in Figure 1.  
Many authors have examined the environmental impact caused by orphan and abandoned wells in the USA, such as methane emissions, contaminating drinking water, and deteriorating the ecosystem [10; 11; 12]. Also, these wells may undermine the ability to store the CO\({}_{2}\) underground by allowing leakage pathways of the stored CO\({}_{2}\) if they are not appropriately plugged or have well integrity problems. The number of orphan and abandonment wells is uncertain because it was poorly documented and reached more than 123,318 wells in April 2022 [13], but it is expected to be 3.9 million wells emitting around 3.2 Tg CH\({}_{4}\) yearly [14]. In the United States, there are approximately 4.7 million historic and active oil and gas wells, yet only one-third of these wells have been properly plugged [15]. It was estimated that over 4.6 million people live within 1 km of these wells, highlighting the public health risks associated with their proximity [16]. The United States Environmental Protection Agency (EPA) estimates that methane emissions from over 2 million inactive, unplugged wells, including documented orphan wells, amount to a CO\({}_{2}\) equivalent of 7 to 20 million metric tons annually, comparable to the emissions produced by 2 to 5 million cars.