Abstract: There are abundance of conventional and unconventional hydrocarbon resources in the Earth, in which the tight oil and gas are considered to be the major types of unconventional hydrocarbon resources in replacing the conventional oil and gas in the next few decades. The characteristics of tight reservoir include high resource quantity, wide distribution area, strong diagenesis, low unit production and high heterogeneity. Therefore, “sweet spots” reservoirs with favorable physical properties are good exploration targets for achieving higher oil and gas production in tight reservoirs. The origin of “sweet spots” reservoirs could be two types: the abnormally high porosity zone or fracture development zone. Recently, much attention has been paid to the tight reservoir researches on reservoir classification, geological characterization, forming mechanism and “sweet spots” prediction, among where genetic mechanism and precise prediction of “sweet spots” have become the focus of scientific investigation. For this reason, reservoir microscopic pore throat structural representation and fracture identification and characterization are the present core issues and future main directions in the tight reservoir exploration and development.

Key words: tight reservoirs, sweet spots, forming mechanism, characteristics of microscopic pore throat structure, identification of the reservoir fractures