The effect of sedimentary microfacies on wettability of tight sandstone in coal-bearing strata: a case from Ordos Basin, China

With the advancement of mining and exploration technology, tight sandstone gas reservoirs in coal-bearing strata have greatly attracted people's attention. As a surface property of tight sandstone, wettability is critical in gas recovering process. The sedimentary microfacies indirectly affect the sandstone wettability by controlling its composition and structure. It was found that in general, the sandstone samples deposited in sedimentary microfacies with a strong hydrodynamic force, such as subaqueous distributary channel, the barrier bar and sand flat are strongly-moderately water wet with higher gas content and higher expected gas recovery, while the sandstone samples deposited in sedimentary microfacies with weak hydrodynamic force or high interstitial contents are usually weakly water wet with lower gas content and lower expected gas recovery.