Horizontal drilling and slickwater hydrofracturing have enabled shale gas to become a significant contributor to the United States’ energy supply. Hydrofracturing typically requires 2MM – 6.5MM gallons of water per shale gas well. About 15-25% of this water returns to the surface as “flowback” within 30 days after hydrofracturing. “Produced water” continues to
flow at a much reduced rate, e.g. 2-10 bbl/day, for the life of the well. In addition to high salinity and hardness levels (Mg, Ca, Sr, Ba), produced water may also contain significant levels of naturally occurring radioactive materials (NORM), particularly radium. In Texas, increasing amounts of produced water is being re-used for hydrofracturing, whereas for disposal by deep-well injection (UIC). In Pennsylvania, up to 95% of the flowback and produced water is reused in subsequent hydrofracturing operations. This paper provides an overview of the potential demand for pruduced water in the Permian Basin and the opportunities for re-use for hydrofracturing or other uses. Currently, a growing volume of high-TDS produced water is being deep-well injected, increasing the risk of induced seismic activity such as that documented in Oklahoma. This paper examines the economics and risks of disposal vs re-use of water and/or salt recovery, including an overview of recent technological develoments, incluidng cost-effective softening technologies, primarily for barium and radium removal, that enable thermal recovery
of distilled water and a salable salt product from produced water.

Primary Author/Presenter:
Richard Bost
12M Associates, LLC
Waller, Texas