This is a book on the basic concepts of well logging and Petrophysics. It explain the Exploration history of Pakistan hydrocarbon reservoirs. Although it is written for Graduate geologists, geophysicists, and engineers, it can be useful for student who want to get the related information of exploration activity in Pakistan. It does not claim to provide all information about well logs from all perspectives. Like the original report of the project, it remains focused on the interpretation of basic, or common open hole logging measurements. It also remains focused on the traditional interpretive goals of Formation porosity, Fluid saturation, and lithology. The idea for this work came from a discussion in ATC(Annual Technical Conference-2013)with Department of Geology,UOP Technical Staff, and myself. The book is part of the project in which I was involved titled as “Qualitative and Quantitative Petrophysical Analysis of Qadirpur-wells central Indus Basin Pakistan”. The goal of this book is to explain in plain language for the nonspecialist about well logs,Formation Evaluation and how log explain the story of a reservoir at depth.