Influence of particle size on gas-adsorption experiments of shales: An example from a Longmaxi Shale sample from the Sichuan Basin, China

•Low-pressure CO2 and N2 gas adsorption experiments were performed on shale samples with particle sizes from 4 to 0.058mm.•The influence of particle size on low-pressure CO2 and N2 gas adsorption experiments of shales was analyzed.•A particle size of 0.113mm (130 mesh) is optimum for shale samples used in low-pressure CO2 and N2 adsorption experiments.