Morris Hoagland explores the ways produced water can be reused in and outside the oilfield and the opportunities this creates.
Every year billions of barrels of Produced Water (PW) are generated from oil and gas production around the world. As fields age, they generate higher water to oil ratios. In some mature fields, 10 barrels of water are generated for every barrel of oil produced. This is not a problem offshore where oil can be recovered from the PW so that it can be discharged overboard. However, it is becoming a problem in some onshore fields.
There are two primary destinations for PW from onshore operations. Most of this water goes back into the producing formations via injection wells as part of IOR and EOR programs to get more production from ageing fields. Historically, excess PW not needed for sweeping producing formations has been disposed of in Class II Saltwater Disposal wells (SWD). With the emergence of fracturing technology, a great deal more PW is now going to SWD facilities. In recent years these higher disposal volumes have led to seismic events in several states. This has caused regulating agencies to cut back on permitted disposal volumes in Seismic Response Areas (SRA) and in some cases to shut down permitted disposal entirely. The result is operators are spending more to ship PW further and then paying higher prices for disposal volumes, especially at SWD facilities just outside of the SRAs.
This risk issue clouds planning for future development in some areas of Oklahoma and West Texas that have seen the most seismic activity. Reducing volumes to local SWD disposal facilities is only part of the scene. The longer-term risk is that a major earthquake could result in the regulators shutting down disposal in large areas. This could force operators to stop production in previously profitable fields. There are options to disposing of excess PW in SWDs. There is growing beneficial reuse of PW in oilfield operations and potential for beneficial reuse outside the oilfield.
Beneficial reuse of PW in the oilfield
The Marcellus was the first shale play where PW began to be reused in the oilfield at scale. This was driven by two factors. It was costing up to US$10/bbl to ship PW to out of state SWDs because Pennsylvania had only nine permitted SWDs. The operators put pressure on the fracking package chemistry providers to develop saltwater tolerant formulas. The goal was to allowed slightly treated PW to be reused for fracking instead of only using fresh water. The development of salt tolerant fracking chemistry was a game changer for managing PW in the Marcellus. Operators worked together to form consortiums for sharing water. This led to a new midstream water industry developing almost overnight to treat and move PW around the shale play.
It took close to a decade for this practice to expand at scale beyond the Marcellus. SWDs are abundant in the other shale plays around the USA and enough water was available to allow continued use of the lower cost fresh water chemical formulations for fracking. Some operators began working at small scale with testing PW as a portion of their frack water requirements. However, it was seismic activity in the Arbuckle formation in Oklahoma that captured the attention of regulators and the operators. Oklahoma regulators shut down some SWDs and limited disposal volumes in others. Then the Texas Railroad Commission initiated a program to monitor seismic activity focused on the Permian Basin. Ultimately this program led to SRAs and curtailment of volumes to some SWDs.
The industry began to recognise it may need other options beyond SWDs for excess PW. Similar to the experience in the Marcellus, a midstream PW management industry popped up quickly to respond to the operator’s need for PW treatment and logistics. Venture capital money flowed in. Pipelines, water storage lagoons, and treatment plants, quickly came online to manage PW at scale.
Collaborating with operators and service companies, the Produced Water Society developed a guideline for ‘Clean Brine’ to establish a uniform PW treatment target for reuse in fracking.
During the last five years PW reuse in the Permian has gone from virtually none to around 40%. The midstream water companies are behind this transition taking place so quickly. Their investment in pipelines, storage lagoons, and treatment facilities drastically reduced the cost of treating and moving PW around the basin. Five years ago, the cost for treating PW to the clean brine level was about US$0.50/bbl. The cost today is closer to US$0.15/bbl. The pipelines move water around at a fraction of the cost of trucking. In many places it is now less expensive to reuse PW than to dispose of it in SWDs.
| Table 1. Clean brine guidelines for reusing produced water | |
|---|---|
| Salinity | Reported |
| pH | 6.0 - 8.0 |
| Oxidation reduction potential (ORP) | >350 mV |
| Turbidity | <50 NTU |
| Oil | <30 ppm - no sheen |
| Hydrogen sulfide (H2S) | Non-detect |
| Particle size | Filter <25 micron |
Beneficial reuse outside the oilfield
Even if the operators were to use 100% of PW for fracking, that would only amount to reusing about 50% of what is generated in the Permian. Ultimately this high PW production leaves operations vulnerable to disruptions to the disposal option. As a result, there is a lot of interest in reusing PW outside the oilfield. New Mexico has taken the lead at looking into this option with the formation of the New Mexico Produced Water Research Consortium (NMPWRC). Texas and Colorado have also formed consortiums to work toward solutions to this growing problem.
Reuse of PW outside the oilfield requires removing the high salt content. The NMPWRC has been evaluating treatment technologies to desalinate PW to the point that it can be used in agriculture or industry. This brings up an important question: what is the treatment goal? As of this writing, there are no standards yet established for discharge of treated PW for agriculture or other beneficial reuse. Several states have been looking at this issue, but they will likely follow the lead of the EPA. The EPA is planning to publish the data they are working with to establish federal effluent guidelines for PW reuse for agriculture west of the 98th meridian. This will be an important leap forward. EPA discharge guidelines will allow the states to confidently issue permits for discharge.
The big barrier to use of treated PW outside the oilfield has always been cost. Only a few years back desalinating PW was projected to cost US$5-6/bbl. There was no economic incentive for operators to consider this option. More recent developments in desalinating technologies are suggesting costs of US$1-2/bbl at scale. With the cost of SWD increasing, the option of further treating for beneficial reuse becomes more attractive. The midstream companies are already collecting and pre-treating PW at scale. They are in the best position to add the technologies to further treat PW to meet the anticipated discharge guidelines.
Several types of desalinating technology are being evaluated by the NMPWRC. They are generally one of three approaches, thermal, membrane, or hybrid (membrane distillation). All of these technologies are proven in other industries. First, they must demonstrate they are effective on the challenging mix of chemistry in PWs. Then they need to be able to project low operating cost at scale. There was more discussion on these options at the Produced Water Society conference2 in Houston, on 10 - 13 February 2025.
This brings us to the next barrier for broad acceptance of PW reuse outside the oilfield. The development of the midstream water sector has already made reuse of PW in the oilfield lower cost than SWD disposal. This was the key to pushing PW reuse in fracking. However, the midstream water companies have their own SWD wells. So, desalination treatment will have to compete not with the cost the operators were paying for SWD disposal, but with the cost of disposal in the midstream companies own SWDs. There are two more factors that could help push the economics in favour of desalination, they are incentives and valuable mineral recovery.
What incentives could encourage the midstream companies to desalinate their clean brine? There are market and government incentives that could help move the dial, but both of them are small. Most of the oil produced in continental USA is in relatively arid regions. Providing fresh water from these operations does have some incremental market value, even for agricultural use. Then water going to improve public lands and range lands might garner tax incentives. While both of these incentives are small, the cost gap between desalination and SWD disposal is narrowing.
A potentially bigger economic mover is mineral recovery. PW has a broad range of minerals making up the Total Dissolved Solids (TDS) that may range 50 000 – 250 000 ppm. Most of this is sodium chloride. Many of the more valuable minerals are too dilute to be economically recovered. However, the desalination of PW generates a heavy brine by-product. This brine now has a concentration that makes mineral recovery potentially quite profitable when operated at large scale. Some of the minerals have significant market values. Examples of commodity prices are in Table 2.
| Table 2. Commodity prices for some PW minerals | |
|---|---|
| Minerals | Value |
| Bromine | US$4100/t |
| Calcium Chloride | US$900/t |
| Iodine | US$28 000/t |
| Lithium | US$10 000/t |
| Magnesium | US$2600/t |
The value of fresh water in arid regions and potential government incentives will narrow the cost gap between desalination versus SWD disposal. Then projects to recover valuable mineral resources from the concentrated brines could turn PW from a waste into a valuable resource. However, mineral recovery will only be feasible when operating at scale requiring large upfront capital investment.
Conclusion
Reuse of PW back into oilfield operations is already actively practiced in the Marcellus and Permian shale plays where the cost for reuse is often lower than the cost for SWD disposal. Even if all fracking projects eventually utilise only PW, there remains huge quantities in excess of that demand. Disposing of this excess PW is leading to seismic activity in several regions that has resulted in curtailment and sometimes shutdown of SWD facilities. This leads to higher cost for operators to move the PW beyond SRA boundaries. Continuing seismic activity could force operators to shut in wells producing high rates of PW.
A number of factors are converging that are creating an opportunity for beneficial reuse of PW outside the oilfield to gain traction. When operating at scale, the cost of desalination of oilfield brines has decreased substantially. The cost for pre-treating, transporting, and storing PW has gone down due to the emergence of the midstream water industry. State and federal regulators are finally beginning to address discharge guidelines. When operating at scale, mineral recovery from PW concentrated brines can be profitable. Over the next decade beneficial reuse of PW outside the oilfield will become an accepted practice.
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