Management of Water for Unconventional Oil and Gas Operations Enhanced with the Expanded U.S.Geological Survey Produced Waters Geochemical Database

Abstract:

Increases in hydraulic fracturing practices for shale gas and tight oil reservoirs have dramatically increased petroleum production in the USA, but have also made the issue of water management from these operations a high priority. Hydraulic fracturing requires ~ 10,000 to 50,000 m³ of water per well for injection in addition to water used to drill the well. Initially much of the water used for hydraulic fracturing was fresh water, but attitudes and operations are changing in response to costs and concerns. Concerns about groundwater depletion and contamination have prompted operators to increase the amount of produced water that can be recycled for hydraulic fracturing and to find suitable locations for salt-water injection. Knowledge of the geochemistry of produced waters is valuable in determining the feasibility of produced water recycling. Water with low salinity can be reclaimed for use outside of the petroleum industry (e.g. irrigation, municipal uses, and industrial operations).

The updated and expanded USGS Produced Waters Database available at http://eerscmap.usgs.gov/pwapp/ will facilitate and enhance studies on management of water, including produced water, for unconventional oil and gas drilling and production. The USGS database contains > 160,000 samples. Expanding on the 2002 database, we have filled in state and regional gaps with information from conventional and unconventional wells and have increased the number of constituents to include minor and trace chemicals, isotopes, and time series data. We currently have produced water data from 5,200 tight gas wells, 4,500 coal-bed methane (CBM) wells, 3,500 shale gas wells, and 700 tight oil wells. These numbers will increase as we continue to receive positive responses from oil companies, state oil and gas commissions, and scientists wanting to contribute their data.

This database is an important resource for a wide range of interested parties. Scientists from universities, government agencies, public municipalities and citizens can determine the geochemical nature of deep groundwater supplies, contamination sources, and impacts of hydraulic fracturing. Energy companies can utilize the database for determining the suitability of water reuse and for identifying regions where non-potable hydraulic fracturing water may be obtainable.