Influences of Low Salinity Waterflooding on Oil Recovery and Wettability of the Medium and Low Permeability Sandstone
Low salinity waterflooding is a cutting-edge improved water flooding technology with the advantages of low cost and environmental friendliness. The physical properties of medium and low permeability reservoirs in Daqing Oilfield are poor, and the effect of chemical flooding is not ideal. However, low salinity waterflooding has a good application prospect in medium and low permeability reservoirs. In this paper, five medium and low permeability cores from Daqing Oilfield were selected, and salt water with salinity of 1000 mg·L-1 to 10000 mg·L-1 was used to conduct core displacement experiments and contact angle tests. The results showed that when the salinity of injected water decreased from 10000 mg·L-1 to 5000 mg·L-1, oil recovery increased, the isopermeability point shifted to the right, oil saturation decreased, and the reservoir became water wet; when the salinity of injected water decreased from 5000 mg·L-1 to 1000 mg·L-1, the recovery factor decreased, the isopermeability point shifted to the left, and the displacement pressure increased, causing clay swelling, increasing oil saturation, and the reservoir became neutral wetting. Therefore, using low salinity waterflooding to develop medium and low permeability reservoirs in Daqing Oilfield is feasible, which can improve crude oil recovery and injection capacity, and the mineralization threshold is 5000 mg·L-1.
Low salinity waterfloodingMedium and low permeability reservoirsOil displacement efficiencyRelative permeabilityWettability
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