Sustainable fracking: produced water recycling

produced water recyclingSustainable energy has always been a hot topic among environmental groups.  These days, hydraulic fracturing is receiving similar attention.  However, fracking is less of a hot topic than a hot debate. Unfortunately, a lot of activists seem more interested in demonization than innovation.  Let’s see if we can expand the discussion.  When we’re talking about sustainable energy, we mean energy that can be produced without exhausting some limited resource.  While we’re still a long way off from efficient sustainable energy, sustainable fracking is certainly a possibility in the meantime.

One of the major issues environmental groups have with fracking is the massive fresh water use.  Every year, hydraulic fracturing operations in the United States generate around 21 billion barrels, or 882 billion gallons, of produced water8.  Over twice that amount of produced water is generated worldwide8.

And in a lot of cases, this water goes back underground after use.  The most common method of produced water disposal is reinjection.  That is, produced water that is no longer potable is deposited back underground in a closed reservoir.   In other words, a limited resource is used up—the process is not sustainable.    As hydraulic fracturing expands in dry western states it is becoming increasingly important to look for innovative ways to stretch and preserve limited water resources.  An elegant solution to this problem is to recycle produced water for reuse in fracking operations.  In this sense, fracking can be done sustainably through the recycling of a finite resource.

How do we recycle produced water?

When water returns to the surface after fracturing operations, it contains all manner of new solutes that were not there before.  Underground, water may pick up minerals, salts, oil and gas compounds, and even microorganisms.  In order to successfully fracture a well, engineers must have very precise control of the properties of fracking fluid, meaning they must also have close control of the composition of the fluid.  Accordingly, produced water requires varying levels of cleaning and treatment before it can be reused.  In a sense, for water associated with fracking operations, the slate must be “wiped clean” before the next chapter can begin.

produced water treatment stagesWhile processes for treatment vary and are often proprietary, they are certainly available.  However, this necessary step is the main obstacle to widespread recycling of flowback water.  Treatment processes involve multiple stages of treatment and filtering and are often cost prohibitive in comparison to reinjection.  To further complicate matters, produced water composition varies with well location and even with fracturing stage, meaning treatment processes must be adjusted to fit.

Is sustainable fracking happening? Why and why not?

Recycling produced water for fracking is definitely a technological capability.  However, the incidence of this practice varies greatly from region to region.  Prevalence of sustainable fracking is dependent on what may be seen as negative and positive motivators.  Positive motivation is provided by economic advantages of recycling in areas where cheap disposal is not accessible or where water price is exhorbitant. Negative motivation comes in the form of governmental regulation or restriction of standard disposal methods.  Let’s look at two regions where these factors have combined to produce very different effects.

Texas

Texas has long been a hub of oil and gas production and was one of the first areas in the nation to begin producing unconventional shale gas reserves using hydraulic fracturing.  A state with this history, combined with the scarcity of water in the region, could be expected to be at the forefront of produced water recycling technology.  So is this the case? Yes and no.

Texas is a leader in flowback recycling in that it is a center of innovation and development for new techniques and systems.  In particular, a partnership between Texas A&M University and the Texas Water Resources Institute has produced promising results.  The collaboration involved the formation of a multidisciplinary team led by the Department of Petroleum Engineering with the goal of developing

technologies to treat produced water and make it safe for use in agriculture and wildlife habitat restoration3.

And there is a growing awareness that water cleaned to these standards could in fact be reused in the fracturing process.

reverse osmosis for produced water recyclingSpecifically, the Texas A&M team is focused on developing a mobile, low cost desalination unit using reverse osmosis technology3.  Among the different contaminants that can be found in produced water, high levels of salt are by far the most common and prevalent.  To this end, the major challenge in treating produced water is desalination.  Reverse osmosis involves pumping water past a semipermeable membrane at high pressures.  Sufficient pressure causes water to flow through the membrane, leaving behind the salt and producing a pure stream.  A challenge to creating a commercial unit is the inability to create a standardized system and offer standardized price projections.  The amount of pressure needed—and thereby the operating costs—depend directly on the salinity of the water, a quality which will vary from well to well5.

omni water solutions produced water recycling system

Omni Water Solutions’ mobile produced water treatment system.

Nevertheless, a Texas start-up called Omni Water Solutions is overcoming this challenge.  The company has created a mobile, produced water treatment unit utilizing what’s being marketed as OctozoneTM technology.  OctozoneTM is a proprietary system that uses sensors and computer programming to automatically determine unique inflow water content and adjust treatment accordingly4.

Surprisingly, produced water recycling is still a rarity in Texas.  In fact, according to a 2012 study by the Texas Water Development Board, only 2% of water in the Permian Basin and 5% of water in the Barnett Shale was recycled7.  Financial considerations provide a clue as to the cause of the discrepancy between innovation and use.

‘Recycling for us — it varies from area to area, again — is 50 to 75 percent more expensive than the alternatives,’ said Jay Ewing, a Barnett Shale-based representative of drilling company Devon Energy.2

This is due to the fact that Texas geology provides numerous cheap and local disposal well locations2.  Furthermore, Texas fracking regulations do not significantly restrict reinjection within the state.  In this way, sustainable fracking is uncommon in Texas as companies lack both negative and positive motivations.

Pennsylvania

In comparison to Texas, hydraulic fracturing in Pennsylvania is relatively new.  That is, use of the technology has seen exponential growth in the state in the past few years following the discovery of Marcellus Shale gas reserves.  Interestingly, Pennsylvania has far surpassed Texas in use of produced water recycling techniques.

In Pennsylvania, the prevalence of sustainable fracking can be attributed mainly to negative motivation.  Unlike in Texas, Pennsylvania geology makes for a lack of viable locations for reinjection.  As a result, prior to 2011, most produced water generated in the state was treated in public water plants before being discharged into local bodies of water6.  However, in response to concerns voiced by citizens and environmental groups, in the spring of 2011, the Pennsylvania Department of Environmental Protection (DEP) issued an order to 15 public water treatment plants, forbidding them from accepting produced water for treatment6.  The ban on in-state treatment with available infrastructure immediately caused disposal costs to spike as companies were forced to contend with expensive transport and out-of-state treatment options.

 produced water treatment system in pennsylvaniaIn response, companies were pressured to give recycling serious consideration.  The company Range Resources led the way in conversion to recycled fracking fluid6.  Range was exploring reuse of flowback water as early as 2009, when it experimented with a mixture of flowback and fresh water6.  However, in the subsequent several years, Range converted to almost 96% reuse of its produced water6.  Since then, other Pennsylvania producers have followed suit and the Marcellus Shale has become “a proving ground” for sustainable fracking techniques6.

 

 

References:

1)       (2008). Challenges in reusing produced water. Society of Petroleum Engineers,

2)      Galbraith, K. (2013, March 19). In texas, recycling oilfield water has far to go. Texas Tribune

3)       Morales, G., & Barrufet, M. (n.d.). Desalination of produced water using reverse osmosis. Informally published manuscript, Department of Petroleum Engineering, Texas A&M University,

4)      Omni Water Solutions. (2013). Mobile water treatment solutions.

5)       Pankratz, T. Texas Water Development Board, (n.d.).Desalination technology trends

6)       Rassenfoss, S. (2011). from flowback to fracturing: water recycling grows in the marcellus shale. Journal of Petroleum Technology, 48-51.

7)       Texas Water Development Board, (2012). Oil and gas water use in texas: Update to the 2011 mining water use report

8)       US Department of Energy, National Energy Technology Laboratory. (2013). Produced water management information system: Introduction to produced water

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