Multi-scale characterization of pores in shale by nitrogen adsorption and high pressure mercury methods

High pressure mercury and nitrogen adsorption had been conducted on outcrop and core samples for studying the pore structure characteristics about shale in eastern uplift of Liaohe depression. The results showed that: The pores mainly are nano-scale and irregular in size and arrangement. The nitrogen adsorption curves about shale are type II, and the adsorption loop can be divided into 3 types: type P1 represents the pores dominated by airtight pores with one end closed; type P2 demonstrates the pores dominated by ink-bottle pores and airtight pores with one end closed; type P3 represents the pores dominated by open pores and airtight pores with one end closed. The distribution of pores has two peaks that the pores' average diameter is 4nm and 6μm respectively. The mesoporous and macroporous pore volume accounted for 85% of all, and they provide the main place for free gas. The surface area of mesopore and micropore accounted for 97.86% of all, and they enhance the adsorption capacity of shale.