This book presents the fundamentals of the reservoir and interfacial engineering. The book systematically starts with the basics of primary, secondary and tertiary (enhanced) oil recovery and emphasizes on the theory of microbial-enhanced oil recovery (MEOR) and its potential toward recovery of oil in place. Different approaches of MEOR such as in-situ, ex-situ, and integration of chemical- and microbial-enhanced oil recovery (EOR) are discussed in detail. This book highlights the link between the effectiveness of MEOR and the local reservoir conditions, crude oil characteristics, and indigenous microbial community. The latest implementations of MEOR across the globe are highlighted as case studies to outline the potential as well as the scope of MEOR. Given the topics covered, this book will be useful for professionals and researchers working in the areas of petroleum science and engineering, chemical engineering, biotechnology, bioengineering, and other related fields.