Uncertainty Is on My Side: Two Views of Field Development and Performance Evaluation David Echeverria Ciaurri IBM Research Uncertainty is often seen as an undesired complication in life. We usually believe that uncertainty makes things harder. We do not stop for a second and realize that certainty is really a ridiculous condition and that uncertainty comes hand in hand with a myriad of opportunities. In the presence of uncertainty, strategies that leverage formal decision-making methodologies frequently beat approaches that rely heavily on gut feeling, experience and heuristics. In this talk I will describe two industrial research projects performed at IBM where uncertainty is a key component. In the first project, we aimed at developing a tool for rapid evaluation of oil fields under uncertainty, which can be used to support decision-making in field acquisition. The second project deals with the construction of field development plans based on decision trees, taking into account the acquisition of new information in the future by means of appraisal wells.