Pore structure and fractal characteristics of a tight gas sandstone: A case study of Sulige area in the Ordos Basin, China:

To understand the pore structure and fractal characteristics of tight gas reservoirs, thin sections, nuclear magnetic resonance, rate-controlled mercury injection, microcomputed tomography scanning, and field emission scanning electron microscopy investigations under laboratory conditions were conducted on a suite of core samples from the Middle Permian Shihezi Formation of Sulige area in the Ordos Basin, China. The investigated tight gas sandstones comprise three types of pores, i.e. residual intergranular pore, secondary dissolution pore, and micropore. The pore–throat size distribution is extremely wide and multiscale (10 nm–400 μm) co-existing in tight gas reservoirs. The submicron- and micron-scale pore–throats with radius above 0.05 μm, which are characterized by combining rate-controlled mercury injection with nuclear magnetic resonance, are considered to be the effective pores and throats that dominated the reservoirs flow capacity. Tight gas sandstones have stage fractal characteristics, and the ...