seawater injection plants

Hi All I am ​​interesting to ​​know the ​​industry ​​practice for ​​treatment of ​​seawater used ​​for oil well ​​injection. ​​ Can anyone ​​share with me ​​the criteria ​​for technology ​​selection and ​​challenges ​​associated with ​​it. Best Regards Anvar Mansuri