This book is written by Dr. Saeid Pourmorad, Prof. Khan M. G. Mostofa, Prof. Si-Liang Li, Prof. Cong-Qiang Liu (From Tianjin University of China) and Ms. Zinab Moein (From Chamran University of Iran), divided into two main sections: geology and Mud engineering. In the geology section, an attempt has been made to ignore the basic topics of geology as much as possible, and to focus more on operational issues and to examine all the cases that a geologist needs in oil and gas fields.In this section, in addition to all the instructions and methods of studying sediment samples, it has two other important features. One of these features is the introduction of 4 new Key beds in the cap rock of oil fields, which have been approved in southwestern Iran and many of the problems caused by the previous Key beds have been resolved. Another feature of this section is the complete training of geological studies with the help of Log Plot software.In the second part of the book, in a completely practical way, which is the result of years of personal experience of the author, he has trained all the requirements of Mud engineers and Mud logging engineers in oil and gas fields.