Effect of pore-throat structure on gas-water seepage behaviour in a tight sandstone gas reservoir

•Considering its physical properties and characteristics, pore-throat structure coefficient is defined.•Pore-throat structures are divided into three types based on pore-throat structure coefficients and mercury injection curves.•Movable fluid distribution and relative permeability characteristics are quantified for different pore-throat structures.•As pore-throat structure becomes worse, its critical movable throat radius and cumulative porosity contribution decrease.•With a deteriorated pore-throat structure, water locking saturation and damage coefficient increase.