Treating Eagle Ford Shale Frac Water Viable Solution?

One of the biggest concerns that many South Texas residents have about the Eagle Ford shale oil and gas boom is the long term effect on water aquifers such as the Carrizo Wilcox. These water “sands” are not so much in danger from hydraulic fracturing, as some environmentalists would lead you to believe, but rather may suffer from depletion due to the amount of water used to frac new wells. How much that depletion amount ends up being is something that has bothered me for a while now.  Chesapeake Energy reports that a typical Eagle Ford shale well requires approximately 6 million gallons of water to drill and complete. With potential spacings as small as 80 acres to the well, and tens of thousands of wells to be drilled across the play, some fear a substantial drop in Carrizo Wilcox aquifer  levels. Another wild card that could come into play is that once all these new water wells are drilled, and oil and gas drilling is mostly over with, will ranchers sell their water rights and allow the wells to be connected up to pipelines, sending Carrizo Wilcox water to cities such as San Antonio?

All Doom And Gloom Or Just A Need To Proceed With Caution?

I’m beginning to come around and accept the fact that the Eagle Ford shale can be developed responsibly, with a minimal amount of impact on the Carrizo Wilcox. I’d still like to see more studies done, but here’s how it looks so far.   If you take six million gallons, which is about how much water that is used to frac a well, multiplied by 8 wells to the square mile,  you arrive at a one – time water use of about 48 million gallons, or 147 acre feet.   (An acre foot, or 325,851 gallons equals the amount of water which will fill a one acre area, one foot deep). Using a little “roughneck math”, on the 640 acre lease (one square mile), on which 8 wells would be drilled and fracked, there would be somewhere around 208,544,640 gallons of water available in a couple feet of the Carrizo aquifer, which is indeed quite thick. See Carrizo Wilcox thickness map below:

(The amount of water held in a vertical section of any aquifer depends on the porosity and uniformity of the formation).   Only 147 acre feet of water would be used for oil and gas drilling on the whole 640 acre section, that’s assuming it will all come from the Carrizo Wilcox, which is not going to be the case. Surface water, from large “tanks” or stock ponds will also be used as frac water, once a normal rainfall pattern returns to South Texas.

Darrel Brownlow, a geologist and former member of the Evergreen Water District, offered a presentation to McMullen County residents recently. Brownlow estimated that there will be between 20,000 and 25,000 wells drilled in the Eagle Ford shale in next 20 years, resulting in water usage of up to 300,000-365,000 ac/ft. That breaks down into 15,000 ac/ft per year or roughly 1,250 ac/ft per the 12 counties that pull water from the Carrizo Aquifer. (That’s assuming it all comes from groundwater sources and not surface sources such as ponds and that no water is recycled.)

A slide in Brownlow’s presentation noted that the 1,250 ac/ft per county includes the drilling and subsequent fracking of “roughly 80 to 100 wells per year per county.”
Brownlow stated that 1,250 ac/ft of water is about the same amount of water that it would take to farm  625 acres of corn.

I love to see detailed information such what Mr. Brownlow presented but would also like to see more studies  to confirm these numbers. For example, I’m skeptical about the amount of wells drilled per county that he offers, I think it will end up being a lot more than that. There have been over 200 permits issued for LaSalle county alone from Jan to Sept 2011.  For more reading, you can find the Carrizo – Wilcox Aquifer report here:  TCEQ Report

Is Recycling Frac Water The Answer?

Recycling frac water in the Eagle Ford shale is one way to reduce the impact on the Carrizo aquifer. There are a number of companies specializing in cleaning up used frac water, removing all chemicals, etc., from it so it can be used again for any number of purposes. This is a great technology and has been used with success in the Barnett and Marcellus shales. Companies are already setting up facilities in some areas of the Eagle Ford shale to clean used frac water. One reason that recycling frac water may not catch on as much in the Eagle Ford shale as it has in other shale plays, is due to the fact that there is favorable geology in much of the region for disposal wells to be used. Disposal wells are utilized to inject used frac and other produced water deep underground into non-productive zones far below  fresh water aquifers. The cost to treat frac water and return it to municipal water or agricultural water standards runs somewhere between $1.50 to $2.00 a barrel. (Correct me if I’m wrong and your company has developed a cheaper method).  In the end, any contaminants removed from it still must be disposed of, in disposal wells, etc.  If an oil company can frac a well with pond water or from the Carrizo aquifer for a few cents per barrel, then inject it into a disposal well for around 50 cents a barrel (add in trucking costs of about $1.00 a barrel), then the economics are simply not that favorable for treating and reusing frac water in those areas of South Texas where disposal wells can be drilled. (On a related note, it has been reported that cities such as Carrizo Springs are selling treated sewage plant water to oil companies for fifty cents a barrel).

In Texas, haulage and disposal costs average $1.47 per barrel. In the more populated East, the costs range from $1.68 to $2.10 per barrel. Source: U.S. Dept of Energy. 5/31/11

Even if treatment costs were on par with disposal costs, and used frac water was treated at a facility somewhere in the area, it still has to be trucked there, stored and then somehow transported to the next well for reuse, however far away that might be.  Six million gallons equals about 142,857 barrels, or about 1,098 vacuum truck loads just to frac one well.  I may be wrong on this one, but  the consensus I’ve been getting from  drilling consultants that I’ve spoken to is that it’s not yet economical in much of the Eagle Ford shale area to treat and reuse frac water. (At least not in those areas where the geology exists to drill disposal wells and obtain well water from the Carrizo aquifer.) This is  a subject I’m very interested in, so feel free to e-mail me if you have more insight on the economics of disposal vs. treatment in the Eagle Ford play.

It’s Not Eagle Ford Shale Drilling That Will Deplete The Carrizo

Here’s what I believe is going to be  the greater threat to the Carrizo Wilcox aquifer  in the Eagle Ford shale play area. It’s not the amount of water that is going to be used by oil and gas companies to frac wells but rather  how all of the newly drilled water wells will be used by landowners after oil drilling is over with. Landowners often end up keeping and using water wells that oil companies drill on their land. In many areas of South Texas, where the Carrizo Wilcox aquifer lies at a depth of several thousand feet, only wealthy ranchers could previously afford to  drill Carrizo wells (which could cost as much as $50,000 or more each). The game changer now is that even small landowners with a few hundred acres could possibly end up with a “free” Carrizo water well worth thousands of dollars, courtesy of the oil company. Let’s just imagine that  one new Carrizo Wilcox water well is drilled for every 2 or 3 square miles of the Eagle Ford shale play. Will the rancher or farmer then decide to put in some kind of crop, and put a high volume pump on the well and use that water for years thereafter, or will they decide to sell their water rights to a municipality such as San Antonio who offers them a deal they can’t refuse? It’s going to be interesting to see how the future “water wars” play out.

Article by Nolan Hart