Micro-nano pore throat structure and occurrence characteristics of tight sandstone gas: a case study in the Ordos Basin, China

To characterise the pore structure, pore throat size and movable fluid occurrence state, a case study was conducted on the Sulige tight sandstone gas field in Ordos Basin. The experiments contented mercury intrusion capillary pressure, nuclear magnetic resonance (NMR), centrifugal test and routine core analysis. The relationship between microscopic pore structure and macroscopic performance was established. The micropores in Sulige tight sandstone gas field is the dominant factor affecting the microscopic pore throat structure characteristics. The transport ability in pore throat is mainly affected by the size of throat and the pore-throat ratio. Due to the frequent alternation of larger pores and smaller pores, the fluid seepage resistance increases greatly, which is attributed to poorer percolation capacity of tight sandstone gas reservoir. The results are also of great significance for the quantitative characterisation of pore structure characteristics and for industry petroleum exploration of tight sandstone gas reservoirs. [Received: June 15, 2018; Accepted: March 29, 2019]