This study contributes to the literature on oil extraction efficiency and sustainability in developing countries. It comprises three chapters addressing distinct facets of this topic. The first chapter investigates the challenges of natural resource depletion and sustainability, incorporating the concept of quality degradation and utilizing metrics such as Exergy Replacement Cost (ERC) and Energy Return on Investment (EROI). These indicators are computed based on data from private oil companies operating in Ecuador from 1972 to 2020. Our findings reveal a concerning trend: as EROI decreases, oil prices rise, signifying an escalating extraction cost and a growing energy input requirement. Most notably, our analysis indicates that post-2034, continued oil extraction in Ecuador may no longer be financially viable due to diminishing field quality, leading to energy costs exceeding energy gains.