歧口凹陷是渤海湾盆地中典型的箕状凹陷，它经历了多期构造演化和多旋回沉积，形成了多种油气成藏组合。中央隆起带油气沿大断裂以垂向运移为主，形成了深、中、浅多层系复式聚集的构造油气藏；凹陷及斜坡区断裂不发育，油气以横向运移为主，形成了大面积叠合连片分布的地层岩性油气藏。两者共同构成了断陷湖盆复式叠合油气成藏、满凹含油的格局。同时，在优质烃源岩分布层段、主砂体带、正向构造背景区以及裂缝、异常高压及特殊岩类储层（碳酸盐岩、火成岩）发育区等优势相区，油气富集、高产，是油气勘探的重点地区。

Qikou Sag, as a typical dustpan-shaped sag in Bohai BayBasin, experienced multi-stage structural evolution and multi-cycle deposition. As a result, various types of hydrocarbon reservoirs were generated in this area. In the central uplift belt, the oil and gas migrated vertically along the major fracture and induced the composite reservoirs form with different depths （low-medium-deep）. Otherwise, in the sag and slope where the fractures were not developed, the oil and gas mainlymigrated horizontally in the source rock strata and formed the stratigraphic lithologic reservoirs which distributed in a large area. Thus complicated superimposed reservoirs and full-sag oil bearing pattern in the rifted lake basin formed after all. Meanwhile, those advantageous phase regions, such as the formation with high quality source rocks, the major sand body belts, the regions with positive structure setting, the reservoirs with abnormal high pressure and special lithology （carbonate rock, igneous rock）, will become the important exploration target for oil and gas enrichment.