The transition to clean and sustainable energy is one of the top priorities in the modern world. Nowadays, the impacts of global warming are evident in almost every country across the globe, and world-leading companies are taking ambitious steps to curb climate change. One of the critical factors that trap heat in the atmosphere are greenhouse gases, where carbon dioxide (CO2) plays the dominant role. Significant amounts of CO2 are produced during the burning process of fossil fuels. Consequently, the primary CO2 emission cuts can be made in places where significant amounts of fossil fuels are burned. However, to be able to control and make improvements in CO2 emissions, the first step is to have reliable CO2 level measurements and estimations across various processes. Being Europe's leading independent natural gas and oil company with more than 120 years of experience as an operator, Wintershall Dea (WD) has ambitious sustainability goals towards decarbonization and is looking to use the best available technologies for the reduction of greenhouse gas emissions (GHG). The estimation/calculation of emissions being created by the company's activities is key in identifying solutions. As a part of this research, WD wants to analyze the company's carbon footprint in rigless intervention and well services activities for the existing operating assets. This research will be done in cooperation with the Global Well Construction team at Wintershall Dea in order to look for methods to accurately determine the amount of GHG emissions from the company's global rigless activities. This thesis aims to pioneer the work in seeking ways to define the amounts of GHG emissions precisely. The aim of this thesis is to understand how and where uncertainty does occur during the emission reporting for rigless well interventions. Followed by the development of a model which assesses the uncertainty and mitigates it for a better monitoring of greenhouse gas emissions. The created methodology can be used and implanted into the already established reporting process to report emissions more precisely.