Water management

We thought the oil price war between Russia and Saudi Arabia was our biggest problem, as we witnessed oil prices drop, then COVID-19 concerns began to spread and, ultimately, we lived through a historic crash in oil demand. Even OPEC + and their production cuts came too little, too late, and oil price continued to tank. It was a “Perfect Storm” that will change the way we operate for months to possibly years.

We have talked about the role of sustainability in oilfield water management and how recycling of produced water was gaining traction. We predicted that 2020 would be a big year for recycling moving the unconventional oil and gas sector in a more sustainable direction. Recycling of produced water was primarily providing minimal treatment to reuse produced water as a completion fluid, and reduce the need for fresh or even brackish water. In order to recycle in this manner, we need wells to be completed, but in this low-oil-price environment, well completions are slowing to a crawl and in some areas have stopped altogether. Obviously, produced water recycling will not grow in 2020, and we may see some in that business fold. So how does that change oilfield produced water management?

The simple answer is that this water will go to a disposal well. But it’s really not that simple. Some operators have developed significant recycling capacity to avoid having to develop more disposal well capacity; those operators will not have enough disposal well capacity and will have to look at third-party disposal wells at a much higher cost.

On the surface, you may say that the biggest beneficiaries of the low-oil-price crisis that the oilfield water management industry is facing are the Water Midstream or commercial disposal well operators. Yet, as we continue to navigate the world of oil oversupply, we are seeing the newest threat, the shutting-in of wells. No more oil, no more water. Shut-ins will happen—how much and how long is still in question. Will shut-ins be prevalent enough that they will impact the Water Midstream or commercial disposal operators? Hard to say today, but I do expect it will impact some of them. The latest projections show a drop in produced water volumes for 2020, something we haven’t seen in years. So, where does this leave the idea of water management?

Surface evaporation. One current strategy that is growing is that of evaporation. What this typically means for most people is surface evaporation using misting nozzles or spray nozzles. This is a common practice in many industries, but we see a common problem repeating itself here. “If it works in other industries, we can use it in the oil field.” Produced water typically has very high salinity and instead of water evaporating into the air, we are leaving a salt plume across large areas, but there are some solutions to minimize this. You can measure wind speed and automate a pump to cycle up or down, based on wind speed. This will minimize what people refer to as carry-over or overspray. The problem is that high wind is typically a friend to evaporation, and limiting spraying will only decrease the efficiency of the evaporation. Some operators have decided that the risk of overspray and the idea of remediating large areas of land for salt isn’t worth the risk.

Thermal evaporation is quite different; this involves heating water above its boiling point, to allow it to evaporate but leave the salt behind. You see, the boiling point of salt is 2,669^oF, as compared to 212^oF for water. Salty water, of course, boils at a slightly higher temperature, but nowhere near the boiling point of salt. This boiling point difference allows thermal evaporation to solve the salt problem, but you will still have tons of salt to get rid of. The other issue is that thermal evaporation requires energy to boil water, which means thermal evaporation is more costly than surface evaporation. We’ve solved this problem by using a newly patented system that uses flare gas, but instead of just evaporating the produced water, it is used to scrub the flare gas emissions in a wet scrubber, while it evaporates. Using flare gas means, in most cases, the energy to boil water is essentially free.

Pit management. The reason that evaporation is even being considered is that some operators are using their pits to store water. This increase in pit storage is a result of some operators not having additional disposal capacity available for the extra produced water that traditionally went into their recycling programs. Others are storing in anticipation of starting completions when the market is right and don’t want to wait the additional time to fill their pits again. Regardless of the reason, storing water in pits brings with it new challenges. The most important challenge being bacteria growth and generation of hydrogen sulfide—a deadly gas. In some cases, aeration can prevent this, but many aeration systems in the oil field aren’t properly sized, and longer storage times can challenge these systems. In some cases, there isn’t any aeration at all. This creates an opportunity for the water management companies. Portable aeration or rental aeration systems are being deployed, to add aeration or supplement existing aeration. This, combined with routine sampling, can help avoid the problems associated with storing produced water and at a much lower cost than pit treatments.

We are facing a challenging time in the oil field today, but with every change, there is also opportunity. I have always been proud of the resilience of the oil field and the companies that work in it. And it’s time for us to show that resilience and pivot toward the services needed. Oilfield water management in the short term will be about disposal, evaporation and pit management. So, let’s get at it.

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.