Seawater sulfate-removal nanofiltration membrane is intended for use in water-injection applications. The SWSR membrane removes sulfate to reduce scale and corrosion in the injection well that can reduce oil recovery and plug the well. The membrane offers good fouling resistance due to its three-layer design and smooth surface. The membrane can be retrofitted into existing systems or used in new systems. Also, it can be used in conjunction with the company’s existing reverse-osmosis membranes to provide water for low salinity flooding, polymer flooding and other EOR methods.