Produced water must be treated to
reduce contaminants before it can be
used in the process again. Imperial says
the main parameters that must be
controlled to avoid scaling and corrosion
in the steam generators are hardness,
alkalinity, silica, iron, oil and turbidity.
“Softened produced water is also used to
provide pump seal water, chemical
dilution and other utility water
requirements.”
The initial step in the treatment process
runs water through hot lime softeners,
which use lime, soda ash and caustic to
reduce iron, calcium and magnesium
hardness, as well as bicarbonate
alkalinity by precipitation. A coagulant-aid
polymer is added to assist in solids
removal, and steam is used to raise the
temperature in the reaction zone to the
105 degrees Celsius required for the
process. At the same time, oxygen is
removed, which is corrosive when
dissolved in water.
“The water comes out at about 25 to 30
parts per million hardness. We have to
get it down to half a part per million,”
Brown says.
The water then goes through a filtering
process, and the final step takes the
produced water through a resin-softening
process provided by weak acid cation
Unlike with SAGD, production is intermittent at CSS developments. Steam is allowed to soak the bitumen exchangers. Brown explains that
for a period of months before it is produced operators keep a close eye on the
SOURCE: Canadian Association of Petroleum Producers process.
Super pads with dozens of wells are used to increase production while limiting surface disturbance
PHOTO BY Joey Podlubny
