In order to prioritize exploration activities, oil and gas companies need to follow a framework. This important procedural envelope is critical to the success of any oil and gas venture. Decision makers need to consider a multitude of variables before they decide whether or not to pursue any petroleum project. Before a decision to drill a well can be made, some important questions need to be answered; some of these questions revolve around the need for assurance that a well will bring wealth to the organization or parties that drill it. A decision maker therefore has to start by asking whether a venture is worth pursuing from an economic perspective. The answer to this question forms the heart of petroleum investment; and supporting this process by building petroleum economic models is what this book is all about. This book offers a basic understanding of the methods required to build economic models for valuing upstream petroleum projects. The book offers an overview of the fundamentals of some of the major petroleum contracts, simple commercial concepts and how to use them for creating valuation models.