The inconsistency of arguments regarding the value of diversification strategies means that there is a lack of a unified methodological approach and a method for evaluating the impact on efficiency and competitive ability of companies. Research shows that diversification was crucially important for oil and gas companies during the economic shocks of 1998, 2009, and 2015. Nowadays, oil and gas companies apply the strategy of green diversification to solve climate change problems and adapt to energy transition trends. The goals of 14 global oil and gas companies with regard to carbon neutrality were analyzed in this study. This research expands the theoretical studies of diversification processes and outcomes in the oil and gas industry and contributes to the discussion of the feasibility of companies implementing renewable energy projects. The factors that prompt oil and gas companies to adopt green diversification were formulated, and their key strategic priorities were determined depending on the volume of proven resources. The research suggests that global shocks in the international energy market and a reduction in the significance of oil and gas resources in the overall power balance stimulate companies to diversify their asset portfolios, but such strategy does not protect against negative impacts. In addition, important issues were identified for further analysis.