This paper discusses technical drivers that influence the produced/flowback water management goals and decisions in unconventional hydrocarbon developments and then presents case studies and a decision tree chart for effective water treatment. Produced/flowback water quality in shale projects is influenced not only by the formation, but also by the fracturing fluid introduced to the formation during hydraulic stimulation. The water produced by shale wells can contain suspended solids, dissolved solids, organics including hydrocarbons and residual fracturing fluid chemicals, and bacteria. Furthermore the water composition can change rapidly during the short flowback period followed by gradual stabilization during the production phase. The clean-up treatment of water with complex and highly varying quality with an effective and robust treatment process presents specific challenges.
Conventional oilfield water treatment technologies may not be always effective in unconventional gas projects due to specific constituents in produced/flowback water such as residual polymers. This paper describes the functional water treatment steps, which target the most common removal of suspended solids and oil/condensate from flowback water/produced water for recycling or disposal operations. In addition pilot tests were run to validate and assess the performance of solids and oil/condensate removal processes. One key learning is that residual guar gum polymer in the water has a major impact on treatment effectiveness and thus the equipment selection process.