On Water... Organic Contaminants
After a little hiatus, we are back with part two of our series on flowback water treatment issues and technology. After water, sand and dissolved solids the next are of interest to all are the free and dissolved hydrocarbons present in the flowback and producted water.
The driller actually adds very little of these compounds into the frac liquids going down the well. While no recipe is the same, the only real hydrocarbons used today tend to be the glycols used in descaling and some light petroleum distillates for viscosity enhancement. Together these would represent less than 0.1% of the frac liquid volume.
The flowback on the other hand has been known to contain "some" free and dissolved hydrocarbons, that come from the formation itself. Rationally, this makes sense as the frac fluids are held under very high pressure for long periods of time to fracture the well prior to flowback. This would give the compound present in the formation both time and energy to dissolve into the flowback water. Many of these are lighter than water therefore they rise up with flowback. There concentrations are very low in the flowback (normally), typically below 100 parts per million.
The good news is that regardless of concentration, these compounds can and are removed easily with a range of filtration and adsorption equipment readily available to any operator. Technologies such as oil absorbents and physical adsorbent media like activated carbon are inexpensive and provide for easy removal efficiency. These companies are already present in the shale and have off of the shelf technology that can be mobilized to a site in hours, not days or weeks. These technologies have been serving the chemical, manufacturing and related industries for years in this region and the infrastructure is already present to take advantage of these new markets.
This is a positive on two fronts. First, if the water is to be recycled in the fracking operation the removal of these compounds is important to ensure the highest water quality available for the next hydraulic fracture. In the event the this water is to be send off for disposal, the removal of all of the dissolved and free organics is particularly important as the water will be discharged eventually under very strict EPA regulations already in existence. (The National Pollution Discharge Elimination System - NPDES). Every state runs their own NPDES permitting system and any facility with a discharge permit must meet strict discharge guidelines.
As I mentioned in an earlier piece, none of the contaminants found in the flowback water are ones that the water treatment industry has never dealt with or managed. As the drilling continues, so will the continued growth of service firms to assist the drillers with their water management.
Views: 400
Comment
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Comment by Michael Havelka on August 1, 2010 at 5:59pm
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Brian... we agree. I have been pushing for well testing for my industrial clients (establish baseline in neighborhood wells) for at least two decades. That is really what is missing in most debates... a baseline. Thanks!
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Comment by Brian Oram, PG on July 31, 2010 at 1:30am
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Sorry - typo - I meant to say "that our area has shallow" natural gas
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I agree that our area has slow natural gas depositis that are from biogenic sources - not Marcellus. My recommendation is that pre-drilling testing be conducted and if the predrilling testing show methane at 2 mg/L - isotopic analysis be conducted - http://www.isotechlabs.com/applications/energy/
(not affiliated with the website cited)
Also - i did not mean to suggest those chemicals were added to the frac water - these were the organics I have seen in flow back water.
I think the other issue is that we need to start monitoring water level in the freshwater aquifer - in the immediate vicinity of the well. This monitoring would easily document that the well casing and cementing is maintaining a seal and recreating the confining layers and that the pressure created during the fracing is not being transmitted to the freshwater aquifer. Just my thoughts.
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(by refute I mean that they proved that the gas was biogenic, as it had occurred in that well for decades prior to Marcellus drilling).
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Daniel
We live in a very litigious society. Even if there was a mechanism to "certify" that they would be clean (and there isn't), there will still be lawsuits and negative press. Remember that piece in Gasland whereby the resident was lighting his tap was refuted BEFORE airing of the movie, yet not one major media source picked it up. Further, Penn State re-released their study on biogenic (naturally occurring) natural gas in water wells at the time of the Gasland release and again it is not reported.
The reality is that there is solid science behind all of this but unless you look for it you it is hard to find.
Mike
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Comment by daniel cohen on July 28, 2010 at 12:18pm -
Dear Mike & Brian,
If we can accept at face value all that you say about the safety precautions and treatment remedies in place, why wouldn't the oil/gas companies just state that they can certify those procedures and assure the landowners that all will be either O.K. or they (oil/gas companies) will make it O.K.?
Dan
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Brian
Yes, we do see hydrocarbons but not your entire list. Never have I seen acetone in over 60 sites. We do see some petroleum hydrocarbons (like some you mentioned). Since these are not injected via the fracturing process, these come from the hydrocarbon formation. Note that their exist a range of hydrocarbons in these formations, not just natural gas. (shale itself can be cooked to release a broad range of organics). These though are all easily treated both on-site and off with over 50 years of technology.
Thanks
Mike
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From the frac and flow back data I have seen it appears the water may contain benzene compounds, toluene compounds, acetone, naphthalene, and xylene compounds and all other appeared to be at trace levels. Am I on the wrong tracK?
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Comment by Frank Verret on July 1, 2010 at 10:12am
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Exactly what part of the formation does not favor this type of usage. It lies beneath a non permeable layer of bedrock. Injection (Disposal) wells are being used what is the difference.
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Frank... while I am not an expert on DOWS (Downhole Oil Water Separation), the key problem seems to be that the geology in the Marcellus regions does not favor injection wells, which is essentially what you are doing. The idea is a good one if the formation is specifically good for this technology but the geology of the Marcellus appears to be a rather poor place to implement DOWS. Just my opinion, the geologist are best to answer this question.
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