Compatibility of water treatment agents and produced water from oilfield

Aimed at corrosion inhibition and sterilization requirements from conventional produced water (CPW) and polymer-containing produced water (PCPW) in Shengli oilfield, functional agents screening was conducted through agent performance, suspended solids content (SSC), turbidity and filtration time. The interaction between polymer in PCPW and functional agent was discussed based on molecular structure and zeta potential of the functional agents. Results show that SSC of PCPW were significantly increased with addition of diquaternary ammonium salt, polyorganoguanidine and 9-octadecenoic acid imidazoline respectively, while slightly increased with addition of quaternary phosphonate and 9-octadecanoic acid epoxy imidazoline, respectively. Poor water-soluble aggregates were formed between anionic polymer and cationic agent with long chain alkyl groups through electrical attraction coming up with turbidity increased. Retention of aggregates and smaller suspended solid particles on filter membrane generated an increase on SSC, a prolonged filtration time and a darker color of filter membrane. "Deterioration" of water quality will happen with addition of such cationic agents with long chain alkyl groups. For the first time, the influence of polymer on selection of functional agents is figure out, and SSC should be taken into consideration besides functional performance when screening of water treatment agents. Also, the types of functional agents applicable to different produced water are proposed.