DEFORMATION IN DEEPWATER FOLD AND THRUST BELTS AND ITS BEARING ON HYDTOCARBON ACCUMULATION

Deepwater fold and thrust belts are important targets of oil and gas exploration in the world, and the structural deformation and its geological characteristics are the main concerns of oil and gas geologists. Based on seismic interpretation and comprehensive analysis, as well as the characteristics of sedimentation, we made the research on structural style and deformation of deepwater fold and thrust belts and their bearing on petroleum accumulation. There are four kinds of structural styles in the deepwater fold and thrust belts in both the active and passive continental margins, namely, the active continental margin type under subduction, the mudstone detachment,the salt detachment and the gravitational collapse types of deepwater fold and thrust belt under passive continental margins. There are different driving mechanisms, structural characteristics and evolutionary histories, leading to various hydrocarbon accumulation modes. Thrust, imbricate and associated folds dipping landward are well developed in the deepwater fold and thrust belt in the active continental margin, where effective source rocks and reservoirs are lack. The deepwater fold and thrust belt in passive continental margin is further divided into the extensional, transitional and compressional zones, with relevant structures. Besides, there are a large number of oil and gas discoveries in the mudstone detachment and salt detachment deepwater fold and thrust belts under passive continental margins.