Lessons Learned from Brazilian Technical Evolution: CO₂ WAG EOR that has Delivered 50Mt of CO₂ Storage

As the world faces the pressing need to reduce greenhouse gas emissions, balancing energy security with environmental responsibility has become a central challenge. During this transitional phase, oil and gas companies are under increasing pressure to adopt cleaner technologies that can curb emissions without compromising supply. In this context, Carbon Capture Utilization and Storage (CCUS) has emerged as a promising approach to reduce CO₂ emissions from traditional energy systems, and Enhanced Oil Recovery (EOR) techniques like water-alternating-gas (WAG) injection has played a crucial role in this scenario, improving oil production efficiency and supporting carbon sequestration.

The Brazilian Pre-salt fields have advanced this EOR method over the years by integrating WAG injection with Carbon Capture and Storage (CCS) strategies by reinjecting CO₂, which contributes to emissions reduction and facilitates geological CO₂ trapping. The pre-salt area represents around 80% of total oil and gas production in Brazil ( ANP, 2024 ), and more than 50 million tons of CO₂ have already been injected into pre-salt reservoirs through CO₂-EOR ( Petrobras, 2024 ). This paper discusses how CO₂-WAG injection strategies in Brazilian Fields has aligned EOR and CCS goals, reducing the environmental impact and the energy cost of oil and gas production.