Abstract: After 40 years’ operations, the North Jiangsu Basin has been moderately or highly explored. During the 12th Five-Year Plan, a series of exploration results were achieved within the North Jiangsu Basin by strengthening the studies and evaluations on “three new domains” ( new zones, new strata and new types). Larege-scale reserves were discovered in low-permeability deep zones and multiple types of subtle oil reservoirs (e.g. sublacustrine fan, beach bar, and submarine fan glutenites) within the Huazhuang area of Gaoyou sag and the new Qinying area and Funing Formation of Jinhu sag. These discoveries provide a firm resource basis for the stable development of oilfields. Some new geological understandings were obtained in aspects of the formation mechanisms of transtensional faults at slopes, the development mechanisms of high-quality deep reservoirs and the sedimentary modes of various sand bodies of the Dainan Formation in the deep areas of the sags, providing the theoretical basis for exploration planning and the important guidance for practical explorations and incremental discoveries. Moreover, three technologies that were geologically suitable for the North Jiangsu Basin were developed and improved, including seismic data processing and interpretation of igneous rock areas, identification and description of concealed faults, and identification and prediction of various sand bodies in deep areas of sags. They provide grand support for increasing reserves and stabilizing production.

Key words: North Jiangsu Basin, exploration results, geological understanding, exploration technologies, the 12_{th Five-Year Plan}