The World Oil Industry (WOI) developed through two types of economic organization, built up around vertically integrated and internationalized enterprises: the US model, based on private international firms, and the model centered on setting up State-run enterprises, initially in the United Kingdom, Argentina and Mexico. However, from the first oil crisis (1973) onwards, the World Oil Industry has gradually been unbundled through nationalization and the loss of control over the reserves by the oil majors. With this new configuration of the industry, from the 1980s onwards, the strategies of the major international oil companies focused on developing the spot market, while lowering investment and operating costs, introducing correlated diversification strategies, and enhancing industrial concentration through mergers and acquisitions and/or cooperation agreements between companies. The core purpose of these strategic shifts is to obtain control over new oilfield areas. The restructuring processes of national oil industries all over the world—particularly in South America—constituted an important drive aligned with these new guidelines, headed up by the global oil operators. This paper analyzes the changes in the South American oil sector during the 1990s, analyzing aspects involved in awarding mineral rights in the upstream segment. Despite similar policies, market deregulation processes follow different patterns. However, the most significant aspect is an increase in the presence of international private capital in the dynamics of this sector, mainly in regional energy integration processes.