Nano-hydrocarbon and the accumulation in coexisting source and reservoir

By comparison of the types, geological characteristics and exploration technologies of conventional and unconventional hydrocarbon, this paper proposes the concept of “nano-hydrocarbon” and regard nano-hydrocarbon as the development direction of oil and gas industry in the future. Nano-hydrocarbon refers to the research and production, by nano-technology, of oil and gas accumulated in the reservoir system of nano-sized pore-throats. It is mainly distributed in source rocks and the neighbouring tight reservoirs and includes shale oil, shale gas, coal-bed methane, tight sandstone oil and gas, tight limestone oil and so on, with nano-sized diameter of pore-throats in reservoirs. Oil, gas and water in nano-sized pore-throats exhibit poor percolation and phase separation, and are mainly driven by ultra-pressure, thus existing pervasively and continuously in the coexisting tight source and reservoir rocks. China's petroliferous basins develop multiple series such as coexisting tight source and reservoir, carbonate fractures and cavities, volcanic fractures and cavities, and metamorphic rock fractures. Among the series, the first type is located in the center or on the slopes of the basins, where nano-hydrocarbons are accumulated extensively within or near sources and are dominant potential sources. With accumulations within coexisting source and reservoir in the Ordos Basin and Sichuan Basin as examples, the method of “two lines and one area” to prospect continuous-type hydrocarbon accumulation is proposed, i.e. the top and bottom boundaries of a set of coexisting source and reservoir and the boundaries of hydrocarbon accumulation as lines, and “sweet spot” distributing core area as the main exploration target.