American Oil and Gas Reporter - June 2019 - 55

SpecialReport: Water Management
water reuse specification, the operator can standardize a system
around those needs and reduce cost by not overtreating or
overdesigning a system.
In simple terms, bacteria and iron control will be needed. If
sulfides are present, then that should be included as part of the
program. Total dissolved solids (TDS) is controlled by blending
and is less important in slickwater systems. Total suspended
solids (TSS) and oil content can be managed using the operator's
own traditional tank batteries and gun barrel systems, so there
be no need to move beyond those systems. Smaller pits or weirtype tanks can be used to settle solids.
Customization is often a result of poor planning. Proactive
management should allow standardization and prevent too much
customization. That being said, things change. Operators have
to be prepared to change their systems as water quality changes.
Some of this can be handled in a standardized operation, but
sometimes there are unexpected events that require a custom
solution. For example, we have had to employ customization
when we have seen spikes in water quality. The best way to
handle this is to allow for expansion to aeration of treatment
systems to address the spikes.

What contaminants present the biggest challenge for
operators? Bacteria? Iron? Sulfide? Boron? TSS/TDS?
How can different technologies be leveraged to address them?
PATTON: With the prevalence of slickwater systems, TDS
and boron become nonissues, and bacteria and iron become the
most important, but not necessarily challenging. Sulfides can
be less prevalent, but are the most challenging. In lower concentrations (<10 parts per million), a standard oxidation approach
works best. In higher concentrations, air stripping can be the
most cost-effective. There also are hybrid solutions that use
both oxidation and stripping. The challenge is to find the sweet
spot between these approaches to keep costs low.
TSS and turbidity can be challenging based on the goal, but
we have found TSS and turbidity to be mostly misunderstood.
Most TSS can be settled and turbidity is really unnecessary. We
have done plenty of core flow and proppant conductivity tests,
and although they support lower turbidity and TSS, most people
forget that there will be dust loading after treatment-especially
in West Texas-and proppant fines when the proppant is added.
These sources of TSS and turbidity create a very high baseline
and make using aggressive TSS and turbidity goals overkill. We
have seen systems that have been in place for longer than a year
using only gravity settling for TSS control and they are creating
a perfectly suitable recycled produced water at rates up to
40,000 bbl/d.
In terms of specific technologies, we recommend aeration in
the storage phase. We also like using aeration as a pretreatment

step if there is an available location. This is the best way to
reduce overall cost. We also like to utilize our fully automated
ozone systems. They reduce the cost of oxidation, and as a
liquid chemical alternative, there is no liquid chemical storage
required, which reduces cost and improves safety.
As the scale of operations has increased, storage requirements
and the demand for higher blends of produced oxidant for onthe-fly systems also have increased. High oxidizer concentrations
can create compatibility problems with friction reducers and
gels. With the addition of aeration and pretreatment systems,
oxidant demand for on-the-fly systems has decreased, making
it easier to employ without compatibility problems.

What is the best way for operators to select technologies
and best practice for their projects? What are your
thoughts on alternative sources such as natural brine reservoirs
and municipal wastewaters? How do the economics of treating
and recycling produced water compare with these alternative
supply sources?
PATTON: The first step is to develop a realistic specification
for the produced water stream. Then, the use of full-scale pilots
always helps verify field performance. Last, a good water
quality test program is needed to validate results.
Natural brines have become a great alternative to freshwater,
and we are finding that most operators are replacing freshwater
with more brackish sources. Most of the larger municipal wastewater sources in the Permian have been contracted, but there
are still some smaller municipalities that can be contracted
with, but many of these discussions are already ongoing.
However, as operators develop more produced water
recycling programs, it likely will reduce the demand for
alternate sources, making it difficult to consider significant
long-term investments in them knowing they ultimately may
get replaced by treated produced water. But with water
recycling slowly transitioning into full-scale operations,
alternate sources are still needed to bridge the development to
more recycling.
The cost of recycling using a typical service company
model ranges between $0.20 and $0.30/bbl. A companyowned model, where the operator buys the equipment and
we use our own automated ozone systems, has developed
programs at a cost below $0.10/bbl. We have more than
600,000 bbl/d of installed capacity in the Permian today, and
our experience shows that the savings from minimizing
hauling and disposal offsets treatment costs, and then some.
In fact, it reduces the overall cost. Operators not only are recycling produced water at a lower cost than disposal, but
they also are eliminating the need for that equivalent volume
in freshwater or brackish water.

JUNE 2019 55

American Oil and Gas Reporter - June 2019

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