Abstract: With the enhanced geological knowledge,Yanchang Petroleum Group has clarified that the north Shaanxi slope of Ordos Basin has favorable geological conditions for the formation of unconventional natural gas;tight sandstone gas and shale gas are the most practical exploration and development fields.In terms of geological exploration concept,it has been determined that the provenance of the southern Ordos Basin made a great contribution to the development of Paleozoic sand bodies;frequent transgression and regression is the most favorable factor for promoting the development of high-quality reservoirs.The accumulation mode of "mature hydrocarbon kitchen migration for reservoir control" was created to predict the spatial distribution of tight sandstone gas reservoirs.This study focuses on the gas occurrence capacity of sandy laminae developed in terrestrial shale,aiming to find the occurrence space of free gas.The assemblage of multi-disciplines including geochemistry,reservoir,logging and seismology was used for seismic prediction in the sweet-spot of shale gas reservoirs.Meanwhile,the large-scale exploitation of tight sandstone gas and shale gas is guaranteed by applying horizontal-well drilling and completion technologies for terrestrial shale gas,drilling fluid system with reservoir protection function for tight sandstone gas reservoirs,VES-CO₂ foam fracturing technology,liquid CO₂/slick water mixing fracturing technology and other development technologies.Guided by the integrated exploration and development mode,the geological reserves of Mesozoic shale gas reserves and Paleozoic tight sandstone gas were proven to be 677×10⁸m³ and 3000×10⁸m³ respectively,and current natural gas production capacity has reached 6×10⁸m³/a,basically changing the situation of oil development in the south while natural gas production in the north.