Monitoring and control of unit operations for generating steam from produced water

A process for treating produced water comprising the steps of:

• a) providing a process train comprising an oil-water separation unit, a first water treatment unit, a second water treatment unit and a steam generating unit;
• b) providing a by-pass line around the second water treatment unit in the process train;
• c) flowing produced water through the process train;
• d) diverting a portion of the produced water through the by-pass line;
• and,
• e) mixing produced water diverted through the bypass line with produced water flowing from the second water treatment unit to the steam generating unit,
• wherein
• the produced water includes a contaminant at a concentration,
• the steam generating unit has a specified maximum concentration of the contaminant,
• the produced water diverted through the bypass line has a concentration of the contaminant greater than the specified maximum concentration, and
• wherein the portion of the produced water diverted through the by-pass line is such that, upon mixing the produced water diverted through the bypass line with the produced water flowing from the second water treatment unit to the steam generating unit, the concentration of the contaminant in the mixture of produced water is between 75% and 100% of the specified maximum concentration of the contaminant for the steam generating unit.

An apparatus for treating produced water that includes a contaminant at a concentration, the apparatus comprising:

• a) a process train comprising an oil-water separation unit, a first water treatment unit, a second water treatment unit and a steam generating unit connected in series;
• b) a bypass line connecting a part of the process train on an outlet side of the first water treatment unit to a part of the process train downstream of the second water treatment unit and upstream of the steam generating unit, wherein all of the water flowing to the steam generating unit flows from the part of the process train on the outlet side of the first water treatment unit through either the bypass line or the second water treatment unit;
• c) a valve operable to adjust a flow in the bypass line relative to a flow through the second water treatment unit;
• d) one or more sensors adapted to determine the concentration of the contaminant in the produced water at one or more locations in the process train;
• and
• e) a valve controller connected to the valve wherein the valve controller is configured to operate the valve so as to maintain a generally constant concentration of the contaminant in produced water entering the steam generating unit.