"Big Data is the oil of the new economy" is the most famous citation during the three last years. It has even been adopted by the World Economic Forum in 2011. Upstream is no stranger to Big Data. Understanding and leveraging data in the upstream segment enables firms to remain competitive throughout planning, exploration, delineation, and field development. Oil & Gas Companies conduct advanced geophysics modeling and simulation to support operations where Seismic generate significant data during exploration phases. They closely monitor the performance of their operational assets. To do this, they use thousands sensors in subsurface wells and surface facilities to provide continuous and real-time monitoring of assets and environmental conditions. Unfortunately, this information comes in various and complex forms, making it a challenge to collect, interpret, and leverage. Big Data technologies integrate common and disparate data sets to deliver the right information at the right time to the correct decision-maker. These capabilities help firms act on large volumes of data, optimizing all phases of exploration, development and production. Big Data ensure safer, more responsible operations. The aim of this paper is to explain how to use Big Data technologies to optimize operations. How can Big Data help experts to decision-making leading the desired outcomes?