Thursday, May 7, 2009

Shale Gas and Water : The Wrong Perceptions

The United States has abundant natural gas resources. The Energy Information Administration estimates that the U.S. has more than 1,744 trillion cubic feet (tcf) of technically recoverable natural gas, including 211 tcf of proved reserves (the discovered, economically recoverable fraction of the original gas-in-place). Technically recoverable unconventional gas (shale gas, tight sands, and coalbed methane) accounts for 60% of the onshore recoverable resource. At the U.S. production rates for 2007, about 19.3 tcf, the current recoverable resource estimate provides enough natural gas to supply the U.S. for the next 90 years. Separate estimates of the shale gas resource extend this supply to 116 years.

There is a coomon perception that shale gas development used a lots of water and may impact the drinking water quality due to hydraulic fracturing. The quantity of water needed to drill and fracture a horizontal shale gas well commonly ranges from about 2 million to 4 million gallons, depending on geologic formation. These volumes may seem very large, but they are small by comparison to some other uses of water, such agriculture, electric power generation, and municipalities, and generally represent a small percentage of the total water resource use in each shale gas area. Calculations indicate that water use for shale gas development will range from less than 0.1% to 0.8% of total water use by basin.

In some shale gas areas, the water needs may challenge supplies and infrastructure. As operators look to develop new shale gas plays, communication with local water planning agencies, state agencies, and regional water basin commissions can help operators and communities to coexist and effectively manage local water resources. A successful technique would be identification of supplies that do not interfere with the community needs. Similarly the concerns for fracturing fluid contaminating water may be low since fracturing fluid is 95% water and 5% chemicals. And the service companies doing a hydraulic fracturing job ensure through state of the art monitoring systems that fracturing fluid does not leak into fresh water aquifers.

The long-term sustainability of shale gas operations in a given region depends on several factors such as:
> Working closely with the local, state, and federal
regulatory environment
> Coping with the stress placed on the local fresh water supplies
> Effective and economical wastewater management plans

Thus, state regulation for the environmental practices related to shale gas development, usually with federal guidance, can effectively address the regional and state-specific character of the activities in comparison to single federal regulations.

Till now not a single case of water aquifer contamination or excessive use of water straining public supply of water has been observed or reported. Therefore before we make an issue out of everything we need to think that Shale Gas is the future of Gas supply and we need to encourage it.



contango said...

I think that the Shale gas recourses have great potential for the US and the technology being developed will unlock even more unconventional resources abroad. Statoil recently bought into Chesapeake’s Marcellus play in a possible attempt to use the knowledge gains on some of their North Sea plays.

As for as the concern for contaminating drinking water is concerned, I agree that this is generally not an issue since most of the new plays are well below the water table. For example, the fracturing in Haynesville wells takes place below 10,000 feet and Barnett is around 8,500 feet. There are also potential benefits of CO2 injection that could decrease the carbon footprint of these wells.

John D. said...

I now work for a company involved in the Haynesville and Barnett Shale plays and I concur. It is quite a marvel however seeing Schlumberger and Haliburton Frac Trucks Pressurize all that water up to 18,000 PSI ans shove it down hole.