**Preface**

Natural gas hydrate and deep-water hydrocarbon have become hotspots of global oil and gas exploration in recent years. Natural gas hydrate is an efficient and clean energy source with huge resource potential, generally occurring within submarine sediments at a water depth of more than 300 meters, and also in permafrost areas. It is estimated that the global resource of natural gas hydrate could reach up to the equivalent of 20 trillion tons of oil. The natural gas hydrate resources in submarine sediments warrant more attention for their effective exploitation. The key issue is that conventional geological theories and understanding cannot be applied to natural gas hydrate and deep-water hydrocarbon exploration due to their complex exploration and development processes. Therefore, innovative theories and technologies are needed to achieve the commercial exploitation of natural gas hydrate and deep-water oil and gas under complex conditions. Various discoveries and new methods, comprehensive laboratory experiments and field investigations, theoretical and numerical simulations, and a more in-depth understanding of natural gas hydrate and deep-water hydrocarbon accumulation are partly covered by the research results in this book.

> **Tao Jiang, Ming Su, and Zenggui Kuang** *Editors*
