This open access book focuses on the geological conditions associated with oil and gas exploration and complex in China's deep marine strata. The petroleum industry is faced with the challenges of limited knowledge of deep petroleum systems, reduced signal-to-noise ratio of deep reservoir targets, and increased engineering risks associated with drilling and completion of ultra-deep wells. This book tackles these challenges with the introduction and investigation of a variety of geological processes from basin evolution, source rock and reservoir deposition, petroleum generation, migration, accumulation, and redistribution in the three ancient cratons in China. It addresses these geological processes in both sedimentary facies and strike-slip fault controlled reservoirs, including theoretical, experimental, and simulation approaches. In addition, it discusses new advances in the geophysics, drilling, and completion engineering specifically related to the deep marine strata. This book will be very useful for petroleum geologists, geophysicists, engineers, technicians, academics, and students who need to study the petroleum geology and exploration methods.