Water Sources and Disposal Related to Hydraulic Fracturing in Texas
Considerable controversy continues about hydraulic fracturing (HF) and its potential for contamination of shallow aquifers and impacting water resources. In this communication, we focus on the latter and use several plays in the state of Texas, including the oldest shale play in the world, the Barnett Shale, as examples for analyzing historical patterns of water use, consumption, reuse/recycling and disposal. Data were obtained from commercial and state databases, river authorities, groundwater conservation districts, and operators. For example, in the Barnett Shale, cumulative water use from ∼18,000 (mostly horizontal) wells since 1993 through 2012 totaled ∼170 thousand AF (∼210 Mm3) including 26 kAF (32 Mm3) in 2011. Increases in water use per well by 60% (from 3 to 5 Mgal/well; 0.011–0.019 Mm3) since the mid-2000s reflect the near-doubling of horizontal-well lengths (from ∼2000 to ∼3800 ft), offset by a reduction in water-use intensity by 40% (from ∼2000 to ∼1200 gal/ft; 2.3–1.4 m3/m). In the Barnett Shale, water sources include fresh surface water and groundwater in approximately equal amounts, whereas south and west Texas rely mostly on groundwater. In Texas, most of the water used for HF is consumed and relatively little reuse/recycling occurs. Most of the flowback / produced water is disposed through injection wells. The median Barnett horizontal well produces back >100% of the amount of water injected for fracturing, albeit of lesser quality, in the course of the few years following completion, an amount larger than other well-known shale gas plays. For example, Eagle Ford Shale wells return ∼40% of the amount injected. The communication will provide detailed material documenting these findings. Understanding the historical evolution of water use in the longest-producing shale plays should be valuable for assessing potential impacts of HF on water resources in other regions.
AAPG Datapages/Search and Discovery Article #90189 © 2014 AAPG Annual Convention and Exhibition, Houston, Texas, USA, April 6–9, 2014