The assessment of the external or macro-environment in which a company is operating plays an important role in its market research, when it is trying to find the most promising country to sell a new product. Nowadays, the increasing competition is forcing the companies to conduct rigorous market researches in multiple and different stages. In this paper, we focused on building an assessment framework, which will include factors affecting the market choice for an oil and gas treatment process. We have chosen as a case study, the Thiopaq O&G technology, which is a gas sweetening process. We conducted a literature review regarding the existing macro-environmental assessment frameworks in order to extract the most interesting factors for our case study and build a new framework upon them. Then we carried out a survey by sending a questionnaire to the employees working in the O&G industry in order to understand how they rank the identified factors, which are the Political, Economic, Environmental Laws and Competition. Moreover, we attached sub-criteria to each factor in order to have a better insight and be able to rate them from the most to least important. For the data analysis, we used the Best Worst Method (BWM) that is a Multi-Criteria Decision-Making (MCDM) method, so as to have valuable and reliable results. The result of the data analysis gave as the ranking of the sub-criteria according to their significance and then we used a likert-scale to decide which country is the most promising market to sell Thiopaq O&G. According to our respondents the most important factor is Economic while Competition is ranked last, but their sub-criteria showed an interesting variation. The developed framework is a valuable tool that can be used for other products in the O&G industry, while the sub-criteria can change according to the perceptions of the one who is constructing it. Thus, it is an addition to the existing literature related to the evaluation framework of the external environment.