Pore structure and wetting alteration combine to produce the low salinity effect on oil production

Low salinity water flooding is a promising enhanced oil recovery technique that has been observed, in experiments over range of scales, to increase production by up 14% some systems. However, there still no way reliably predicting which systems will respond favourably the technique. This shortcoming partly because relative lack pore scale observations low flooding. led poor understanding how mechanisms on micrometres lead changes fluid distribution centimetres reservoir scales. In this work, we use X-ray micro-CT scanning image unsteady state tertiary Berea, Castlegate, and Bunter sandstone micro-cores. We observe saturations characterise wetting samples using imagery fluid–solid fractional occupancy analysis. Berea sample, observed an additional 3 percentage points during flooding, with large volumes displaced from small pores but also re-trapping mobilised pores. sandstone, 4 point significant displacement retrapping Castlegate just 1 relatively mobilisation. wettability alteration towards more water-wet conditions sandstones, sample. hypothesise structure, specifically topology impacted recovery. find connectivity largest each sample strongly correlated work first systematic comparison response across multiple samples. Moreover, it gives insights into role geometry mobilisation