March 2018

Water Management

Recycling produced water cuts disposal costs
Mark Patton / Hydrozonix

Welcome to the inaugural water management column. “Water, water everywhere / Nor any drop to drink.”

Maybe I’m dating myself, but this excerpt from “The Rime of the Ancient Mariner,” for those of you that remember reading it, reminds me of the produced water management challenges facing many of the shale plays across the U.S. Pit after pit, thousands of barrels of produced water are being aggregated for reuse as a completion fluid, all across the shale landscape. Nowhere are these pits more plentiful than in the Permian basin. A few years ago, a 100,000-bbl pit for produced water was considered large, and there were only a handful, but today, 1-MMbbl pits exist, and many 100,000-to-750,000-bbl pits have spread across the Permian basin. This month, we discuss many of the produced water challenges and trends over the coming months. So let’s dive in, but don’t drink any.

The Permian—the produced water mecca. Nowhere is produced water so plentiful. Although the eight-to-one ratio of produced water to oil has declined to about four-to-one, the volume of produced water is still plentiful. With well completions growing from a rate of more than 800 per month in late 2017, and water production seeing a normal decline per well, we see these trends offsetting each other. 

Thus, we see average produced water production in the Permian basin normalizing around 350 MMbbl per month for the remainder of 2018. Even with 173 new disposal wells installed during 2017, there will be some disposal-challenged areas in the Permian. This is where recycling produced water comes to the rescue. Adding new disposal wells isn’t a quick process. The average time from permit filing to first injection is about 400 days. Recycling can bridge that gap, but it also can relieve some of the pressure to disposal-challenged areas. These trends will be updated in future columns.

Recycling has become easy. A few years ago, it was common to see people pay $0.50 to $0.75/bbl to remove dissolved solids (TDS) and generate tons of sludge to produce a nice clean brine. But today, that’s just too expensive. Completion fluids have become more forgiving, gel fracs have been replaced by slickwater, and you can just leave the TDS in
the water. 

Today, operators can just optimize gathering systems to deal with solids and oil, while improving bacteria, iron and sulfide control with an oxidizer. This can lower costs ranging from $0.10 to $0.15/bbl, to less than $0.05/bbl, while improving water quality. Pit treatments for produced water pits have been replaced by aeration systems for further cost reductions. But be warned: not all aeration systems are the same, and many applications have failed. You must size your aeration system properly to match the oxygen demand of your produced water, but more on that in a later column. And finally, there’s the on-the-fly treatment…

On-the-fly. On-the-fly is a term that refers to on-demand treatment at or near the frac site. Once you’ve delivered a recycled fluid to the produced water pit and the aeration program is maintaining the water quality, there are still upsets and contaminated tanks that necessitate a final polish to recycled produced water. A few years ago, this was the heavy lifting and costed between $0.20 and $0.30/bbl, but today, this is a polishing step at $0.10/bbl. On-the-fly treatment is typically done with an oxidizer, sometimes with a preservative, a fancy way to say you’re adding a non-oxidizing biocide because you worried your oxidizer is going to oxidize your friction reducer, and you want more long-term disinfection. There are many ways to manage compatibility of an oxidizer with a completion fluid, which also will be covered in future columns.

The rise of midstream. Midstream doesn’t just refer to oil and gas anymore. Produced water is going midstream in a big way. Gathering systems and disposal wells are being acquired and consolidated while everybody races to build their large distribution networks for produced water disposal combined with recycling capacity and brackish water distribution. We’ll speak with the major players in this race to acquire and build produced and fresh/brackish water infrastructure. The goal is bigger and better, but who will become the king of the Permian? We will keep you updated on this midstream race.

Induced seismicity. This is not everybody’s favorite subject. Fear over the impact of produced water disposal in injection wells, impacting seismicity and inducing earthquakes, has limited injection in areas of Oklahoma and Ohio. It’s a trend that may grow, but also driving the necessity to recycle and look at alternatives like evaporation. We will track this trend while we provide updates on some alternatives.

The produced water holy grail. Turning produced water into discharge-quality or drinking water for less than $0.50/bbl is the produced water holy grail. Places like the Eagle Ford and Powder River basin can be easier with their lower TDS, in this regard. We will track the progress of some of the different desalination technologies as they move to try to make this possible. We will review the many drivers of this trend and
its progress.

Whose water is it anyway? As produced water moves from waste to resource, landowners are starting to reconsider their position: maybe that water is owned by me, and maybe payment should be made for reuse. This is likely to be the next big challenge for produced water.

Water, water everywhere. Produced water is one of those exciting fields that will continue to evolve. Will we really see shale plays turn into water plays with an oil and gas byproduct? Hang on and let’s dive in. wo-box_blue.gif

About the Authors
Mark Patton
Mark Patton is president of Hydrozonix and has more than 30 years of experience developing water and waste treatment systems for the oil and gas industry. This includes design, permitting and operation of commercial and private treatment systems, both nationally and internationally. He has seven produced water patents and two patents pending. He earned his B.S. in chemical engineering from the University of Southern California (USC) in 1985.
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