Water Management: It’s time to look to our future

(Dedicated to John Patton, 12/5/57 – 11/4/22) 

The recent passing of my brother has given me much time to reflect on my future and although a period of much grief, I would be doing my brother a great injustice if I didn’t find some benefit from this period of reflection. As the last remaining sibling in my family, I think it’s’ important to ponder my future but also our future as a community and an industry. 

Background. We generate more produced water than we can consume, with the vast majority going into disposal/injection wells. We are seeing increases in earthquakes from these injection practices, which is impacting permitted capacity. We recycle but can recycle more. The Permian basin, where most of this water is generated, includes drought-stricken areas covering a significant portion of the basin.  

So, let’s just look at some practical solutions. We can increase recycling from 30%-35% today to 100%, but this will need the cooperation of legislation and landowner support and potentially a royalty format to supplant water revenue for landowners, to give them the financial incentive to allow more recycling on their land. But even that only accounts for 25%-30% of the total produced water generated. What about the remaining 70%-75%? We need an alternative outside of disposal wells. 

Artificial groundwater recharge history. I’ve brought up the topic of groundwater recharge before, but let’s take a deeper dive. In simple terms, groundwater recharge is the hydrologic process of surface water percolating down to groundwater, to replenish it. In the early 1900s, drainage wells were used to collect stormwater to prevent flooding in some areas, but also to drain wetlands to expand agricultural lands. These drainage wells typically tied to existing aquifers and replenished groundwater.  

Although you may not support the practice of draining wetlands, the point is that we have been practicing artificial recharge for some time. This practice of man-made recharge, as opposed to the natural process, is referred to as artificial recharge. Over time, and with the development of our cities and infrastructure, we have paved over areas that once allowed surface water to percolate down to groundwater. Additionally, our growing populations have required us to draw water from groundwater sources faster than they can be naturally replenished.  

By the 1930s, stormwater collection basins became more common, but after WWII there was a significant increase in studies and projects, including an increased interest from the U.S. Geological Survey (USGS). In the 1950s and 1960s, interest had expanded to more studies and projects, ranging from moving water from Northern California to Southern California (to replenish groundwater), to moving water from the Mississippi to the Southern High Plains of Texas for groundwater recharge. Although many of these projects never progressed, some did. In 1967, USGS had a budget specifically for groundwater recharge. In the 1980s, we began to see studies and projects for municipal wastewater used for groundwater recharge. 

Not just percolation. As I mentioned, the natural process involves percolating surface water naturally downwards to groundwater. Early infiltration pits, surface spreading, and trenches were used to capture surface waters, especially stormwater to facilitate groundwater recharge. Sometimes, the geology doesn’t support the percolation or, over time, you see clogging from sediment reducing or eliminating the infiltration you need to percolate to groundwater.  

Because of these concerns, injection wells have been used like the drainage wells we mentioned in the early 1900s, except they’re more like permitted UIC wells. The disadvantage of these types of wells is you eliminate the effect of filtering and adsorbing supplied by the natural geology sitting between the surface and the groundwater, which we’ll loosely refer to as the vadose zone. This natural treatment is referred to as soil aquifer treatment (SAT). The downside of good SAT is a lower recharge rate. So, when you’re eliminating SAT and doing direct discharge using wells, the local agencies will require better-quality water. 

Groundwater recharge today. Today groundwater recharge is being conducted around the world. Sources from groundwater recharge projects include drinking water from public water treatment plants, untreated groundwater, and surface waters—including stormwater, treated wastewaters from different processes and industries, and recycled and reclaimed water. Included in treated wastewaters is treated municipal wastewater. This started as a program referred to as from “Toilet to Tap” and would be used directly as a drinking water source. Yet, there was great public opposition, which should have been expected when calling it “toilet to tap.” Today, that same water is used in groundwater recharge without the opposition. The water was always being treated to drinking water standards, but public perception stopped it. 

Our future. I mention public perception, because it has prevented many applications using produced water, even though the vast majority of the contaminants are the natural minerals dissolved from their geologic formation. Although the focus for produced water reuse outside of the oil field has been agricultural application, matching an agricultural application with a produced water source isn’t always that easy to do. You also have the seasonal nature of many agricultural applications.  

The other option discussed is direct discharge, but in this case, we are essentially wasting the water like we would in a disposal well. But Artificial Groundwater Recharge can be done year-round, can be scaled large enough to take a significant stress from disposal wells and more importantly, produced water is generated in many areas that are already suffering from depleted groundwater. Groundwater recharge deserves to be at the top of our re-use list. And in honor of my brother, I will advocate this every way possible. I’ve said this many times before, but if we can be an energy supplier and, additionally, a net water supplier, how much more value have we created? And beyond that, it’s the right thing to do. 

Technology status. Produced water would require desalination, but it would also require desalination for all the other reuse applications we have discussed, except that groundwater recharge allows the scale to reduce the cost of desalination. And cost has really been the primary obstacle, not technology. We are, ourselves, working on a patent-pending ultrasonic desalination technology that will reduce the cost and become a pre-treatment for conventional reverse osmosis, allowing produced water to meet drinking water standards.  

The challenge is not technology, it will be legislative and public perception and, frankly, much more controversial and contaminated water has gone the path of groundwater recharge. I will keep you updated on my mission to move groundwater recharge to the top of our list for produced water management. 

About the Authors

Mark Patton

Hydrozonix

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.