Clay Science in Drilling and Drilling Fluids starts from the fundamentals of clay science and drilling and then comprehensively presents the advances of clay science related to drilling, drilling fluids, and clay products. The topics combine to present the whole picture of fundamental research and industrial applications of clays and clay minerals in drilling operations, which is of general interest to researchers and engineers working in related fields. This book covers the different levels of clay science in drilling and drilling fluids, i.e., from fundamentals to the latest research results, applications, and commercial products. Oil and gas are the primary sources of energy in human society and the foundation of the petrochemical industry. However, extracting these resources present a number of drilling challenges, including high temperature and high pressure (HTHP), offshore drilling, high angle drilling, and even horizontal drilling, among others. As a result, it is crucial to develop advanced drilling and drilling fluid technologies that speak to these challenges.