Water is the most common and heavily used fluid in the petroleum industry. It is produced along with oil and gas from nearly every well. Fresh water is used as a base fluid in drilling, completion, and production operations. Produced water is handled in three primary ways: injected in salt water disposal wells, for pressure maintenance in secondary or tertiary recovery projects, or as a recycled base fluid in hydraulic fracturing.
In unconventional oil and gas operations hydraulic fracturing is the biggest user of fresh water. The focus of this paper is the procurement, conditioning, transportation, storage, reuse and disposal of water for hydraulic fracturing in Newfield's MidContinent operations.
Newfield's two primary fresh water sources are subsurface aquifers and surface water. The transportation of either fresh water or recycled (produced) water can be done by either pipeline or truck. Where possible it is preferable to transport the water through pipelines. For the transportation of smaller volumes of water 3" or 4" poly pipe is used or the water is trucked. Large volumes of fresh water are generally moved through 10" aluminum irrigation line, although polyvinyl chloride (PVC), lay flat hose, and high density polyethylene (HDPE) are also used. For the transportation of recycled or produced water HDPE has been the choice for most operators.
Newfield's preference for storing fresh water is unlined ponds because they can then be used by a landowner for long term water supply on his or her property. Lined pits are used where the soil conditions will not prevent water from leaking out. Fresh water can also be stored in frac tanks (500 bbl), modular tanks (up to 60,000 bbl), or portadams (sized as required). Recycled or produced water is stored in permitted lined pits, frac tanks, modular tanks, or portadams.
After fracturing a well, the produced water used can be recovered, stored, and reused. If the produced water cannot be reused it will be disposed via deep well injection (most common disposal method) or evaporation (limited use). The amount of produced water recovered after stimulation is dependent on the formation characteristics. Usually from 20 to 80% of the water used during the fracturing operation is recovered within the first 60 days of production and can be reused. Depending on the quality of the produced water recovered, it may require some type of treatment prior to reuse. Newfield began recycling water in its Wheeler County, Texas operations during 2005 because it made economic sense and the company is committed to responsible environmental stewardship.