The steps that lead to the production of oil and gas are diverse, complex and costly. They are diverse, because the detection of oil and gas involves input from many specialties, ranging from geology to reservoir engineering. They are complex, as shown by the development of the job of the petroleum architect, who coordinates all the operations. They are costly, as the investments for exploration and production represent more than half of all investments in the oil and gas sector. Moreover, exploration is a risky activity, both from the technical and financial viewpoint : only one well in five produces marketable oil. Meanwhile, the areas for exploration and production are spread throughout the world. This book provides a complete overview of the stakes and challenges invoived in oil and gas exploration and production. Following a historical review and a survey of the markets, the technical phases are covered, as are the evaluation of reserves, the estimation of investments and costs, the decision-making and control processes, and the accounting, legal and contractual environment for these activities. The book concludes with a discussion of the rote of safety, and of environmental and ethical issues. This work, which is designed for readers concerned with the various aspects of the oil and gas upstream sector, is accessible to all.