CCUS is a technological option with the most significant GHG mitigation potential in the oil and gas industry (O&G). However, there is a need for a systematic assessment of several drivers to understand and determine their feasibility. First, CO2 capture represents the highest cost out of the process stages in the CCUS project, so an appropriate screening of technologies and CO2 sources must be involved in the analysis. Second, the infrastructure cost is based on source to sink distance and CO2 flow considered in the project. Third, the storage potential relies on CO2-EOR technology due to the current high cost of dedicated CO2 storage. So incremental oil revenues partially offset the high CO2 capture cost in a CCUS project. In addition, the three stages should be analyzed in a counter view compared to the regular value-chain in the oil and gas industry. This means that the upstream side in the CO2 value chain represents the downstream of the O&G chain. Therefore, the CCUS assessment might begin by identifying downstream potential in a CCUS project represented by the geological storage potential through CO2-EOR of nearby sedimentary formations to CO2 sources. Unlike emissions from fossil-fueled power plants, the carbon footprint of the O&G sector represents a complex mixture of stationary combustion and process emissions produced as a reaction byproduct of oil production and processing. As a result, a significant amount of data for oil fields and CO2 sources must be analyzed to carry out a source-sink matching and identify the appropriate capture technology to build a business case study.This paper presents a methodological approach for assessing CO2 sources and oil fields to identify and estimate a CCUS potential specifically its use for enhanced oil recovery (EOR) and geologic sequestration in a vertically integrated national oil company. The methodology includes several steps on the building process of CCUS options which start by mapping sedimentary formations and relevant CO2 sources using ArcGis software. This step allows, by running an algorithm, to perform a preliminary screening based on distance-approach criteria, crude oil and carbon dioxide properties and physicochemical interactions, and reservoir's physical properties. Then, optimization and calculation modules are used to assess business cases to estimate the CO2 storage potential, incremental oil reserves and performance economic parameters such as VPN, TIR, and CO2 avoided cost. Three in-house tools were developed to evaluate CO2-EOR potential cases: a) georeferential location between relevant sources and potential sinks, b) techno-economic performance by a CO2-EOR deterministic model, and c) carbon footprint for the incremental oil produced. All these tools combined were used for a quick screening and assessment of promising clusters to develop CCUS projects. These projects aim to maximize the CO2 storage potential through CO2 capture at the oil refinery and deployment of EOR process.Field data from oil basins, refinery process emissions and costs (class V) were used in this assessment. This analysis allowed us to identify four main zones in the country with a joint average recovery potential of around a billion oil barrels and the potential to avoid 7,65 MtCO2/year. considering a closed cycled approach. It is important to remark that the oil recovery potential will be particular for each source-sink case and will depend on the nature of the displacement process at reservoir conditions (miscible or immiscible). The most promising option of CCUS identified in this considers the production of blue hydrogen through the gasification of a heavy refinery residue, the use of CO2 for EOR injection in nearby fields with an associated production of 500 tH2/day, 19 MSTB of incremental oil and roughly 24 MtCO2 avoided at LCOH and avoidance costs of around USD 1,7/kgH2 and USD 200/tCO2, respectively. National regulations of federal tax benefits and carbon credits for CCUS projects were included in the analysis, which represent a significant impact on the economic performance of the project. This study showed competitive results for using CO2 for EOR and storage at current oil and carbon prices when integrated into a hydrogen production process. This assessment proves the viability of energy transition of the fossil industry, based on deep knowledge and experience in energy carriers as well as processes and infrastructure to move forward faster to reach climate change goals.