Low salinity water production in crude oil processing

A system comprising:

• a side-stream branching from an oil phase stream discharged from a crude oil separator in a gas-oil separation plant, wherein the side-stream contains water and oil;
• a coalescer configured to receive the side-stream and apply an electric field across the side-stream to coalesce aqueous droplets present in the side-stream to form an aqueous phase separate from an oil phase;
• a separator configured to receive the side-stream from the coalescer and separate the aqueous phase from the oil phase;
• a heat exchanger configured to receive and evaporate at least a portion of the aqueous phase from the separator;
• a knockout drum configured to receive the aqueous phase from the heat exchanger and separate the aqueous phase into a wastewater phase and a vapor phase;
• a condenser configured to receive and cool the vapor phase to condense at least a portion of the vapor phase into a wash water;
• and
• a desalter configured to receive and mix at least a portion of the oil phase stream discharged from the crude oil separator and the wash water.

A method comprising:

• separating, in a first crude oil separator in a gas-oil separation plant, a crude oil stream into a first gas stream, a first oil stream, and a first aqueous stream, wherein the first oil stream contains water and oil;
• splitting the first oil stream into a first portion and a second portion;
• coalescing aqueous droplets present in the first portion to form an aqueous phase separate from an oil phase;
• evaporating at least a portion of the aqueous phase to form a wastewater stream and a water vapor stream;
• condensing the water vapor stream to produce a wash water stream;
• mixing the oil phase with the second portion to form a rejoined oil phase;
• separating, in a second crude oil separator in the gas-oil separation plant, the rejoined oil phase into a second gas stream, a second oil stream, and a second aqueous stream;
• flowing at least a portion of the second oil stream to a desalter in the gas-oil separation plant;
• and
• flowing the wash water stream to the desalter.