Abstract:

Based on the connotation of unconventional oil and gas, this paper analyzes the geological conditions of tight sandstone oil and gas and shale oil and gas reservoir, demonstrates huge potential for unconventional oil and gas resources, and discusses the strategic direction of unconventional hydrocarbon resources in China. The unconventional hydrocarbon reservoirs are continuous hydrocarbon accumulation consisting of selfgeneration and selfpreservation nanoporecrack system. Tight sandstone oil and gas and shale oil and gas reservoirs break the concept of reservoir trap distribution. Meanwhile, there is no significant “reservoir” boundary. The main characteristics of tight sandstone oil and gas are as follows. (1) Tight sandstone oil and gas are usually found in wide and slow tectonics which coexists with a widely distributed effective source rock. (2) Source rocks and reservoirs develop in the form of interactive multiple layers. (3) Hydrocarbon has short migration which is mainly dominated by nonDarcy flow. Shale oil and gas reservoir is a typical selfpreservation reservoir, but the concept of traps has been diluted. The shale oil and gas reservoirs have following characteristics: (1) shale oil and gas reservoir is mainly formed in the depression or slope of a basin. Therefore, shale has a large and continuous distribution area. (2) The organic matter has high TOC contents and high maturity. (3) The reservoir develops millimetercentimeter laminae, nanoporecrack system which has great brittleness coefficient and high formation pressure. The organicrich source rocks occurred from the Sinian to the Tertiary, deposited in terrestrial facies, marine facies, and terrestrialmarine facies. In a word, unconventional oil and gas resource has huge potential. Conventional and unconventional oil and gas coexist in a sequential distribution of time and space, forming a conventionalunconventional “sequentialaccumulation” system. “Sequentialexploitation” of conventional and unconventional oil and gas breakouts the traditional idea of hydrocarbon exploration, promoting the geological theories of hydrocarbon exploration from the “hot point”, “belt”, “two dimension” to “three dimension” and breaking the thinking of “rich first”.

Key words: unconventional petroleum and gas, strategic thinking, geological condition, potential