Method of sulfate removal from seawater using high salinity produced water

A method of desulfating seawater, the method comprising:

• determining a concentration of sulfates in a sulfated seawater;
• determining a concentration of a precipitating agent in a produced water;
• adding an amount of the produced water to an amount of the sulfated seawater to form a first precipitating solution based on the determined concentration of sulfates in the sulfated seawater and the concentration of the precipitating agent in the produced water;
• agitating the first precipitating solution thereby forming a first precipitate;
• separating the first precipitate from the first precipitating solution to produce a desulfated seawater having a first concentration of sulfate ions;
• measuring the first sulfate ion concentration of the desulfated seawater;
• adding a precipitating agent to the desulfated seawater to form a second precipitating solution comprising a second precipitate, wherein the precipitating agent is a solubilized alkaline earth metal halide selected from the group consisting of barium halide, calcium halide, strontium halide, and combinations thereof;
• and
• separating the second precipitate from the second precipitating solution to produce a desulfated seawater having a second concentration of sulfate ions.