Abstract:

An experimental study of oil migration and accumulation in low-permeability sandstone is performed through injecting fluid into core samples from low-permeability sandstone under computer-controlled pressures.The preliminary results indicate that(1) oil migration in low permeability beds presents the features of non-Darcy flow and most of the flow curves take the concave upward shape and some of them are modified Darcy flow curves;(2) the core permeability has a strong impact upon the locations of flow curves,curvatures and variation range of the non-linear parts,and the intercepts of the linear portions on the pressure gradient axis;(3) the oil saturation in low-permeability cores increases in three stages,including rapid,slow and stable growth,with the final oil saturation mainly ranging from 35% to 60%;and(4) the relationship between oil saturation and porosity or permeability in low permeability cores is not simple linear relationship,but a positive correlation exists between the injection pressure and the oil saturation.

Key words: non-Darcy flow, simulated experiment, oil migration, low-permeability sandstone