Produced water treatment and reuse in hydraulic fracturing: Using
laboratory research to select and implement technology at field-scale
Abstract
Reusing produced water for hydraulic fracturing simultaneously satisfies
challenges of fresh water sourcing and the design/operation of an
extensive disposal well infrastructure. This presentation provides an
overview of a reuse program from concept through implementation
including qualification of advanced water recycling technologies. We
target the most prolific unconventional reservoir play in the United
States – the Permian Basin. Sourcing water for full-field development
therein represents a significant problem since it is in short supply in
(semi)arid regions of West Texas and Southeastern New Mexico. We report
results from a synergistic industry-academia collaboration wherein
desalination pretreatment was first evaluated at lab scale to (i)
systematically evaluate partial softening (i.e. “floc-and-drop”)
versus neutral pH oxidation for iron removal (ii) investigate
synergistic effects of FeCl3 and polymer addition to
destabilize colloids (including particulate iron) and induce high-rate
sedimentation and (iii) develop and implement robust techniques using
video and image analysis to characterize process performance and floc
properties (e.g. morphology, size, and settling velocity). Jar tests and
associated measurements were completed in the range 4 - 44 ºC covering
the range of temperatures measured in the Permian. FeCl3
in conjunction with an anionic polymer dramatically improved colloid
destabilization and floc growth via enmeshment of primary colloids by
amorphous iron precipitates and inter-particle bridging by the adsorbed
polymer. Larger, stronger, and denser flocs thus formed settled
extremely rapidly without breakage (i.e. high rate sedimentation).
Bench-scale results were integrated in the design and testing a 5,000
BPD pilot scale high-rate clarifier. Pilot scale results show that the
neutral pH method of clean-brine generation produced 5-10 times less
sludge while achieving 15-20% higher throughput over the alternative
floc-and-drop method. Both bench- and pilot-scale findings were
incorporated in design and operation of a 50,000 BPD full-scale reuse
facility in the Permian Basin. This presentation will share lessons
learned from operating a large-scale reuse facility and how academic
research can inform and be motivated by industrial practices (and vice
versa).