This book is a compilation of selected papers from the 5th International Petroleum and Petrochemical Technology Conference (IPPTC 2021). The work focuses on petroleum & petrochemical technologies and practical challenges in the field. It creates a platform to bridge the knowledge gap between China and the world. The conference not only provides a platform to exchanges experience but also promotes the development of scientific research in petroleum & petrochemical technologies. The book will benefit a broad readership, including industry experts, researchers, educators, senior engineers and managers.