SAN ANTONIO – Water, water everywhere, but there had better be some left to drink. Water is an issue in drought-plagued South Texas, where oil and gas operators have been competing with agricultural and urban interests for fresh-water sources to use in oil and gas extraction.

With high-stakes, drought-induced political consequences on the line, the oil and gas industry is looking to reduce demand on fresh-water resources by seeking lower-quality water from deep-lying aquifers and recycling flowback and produced water from fracture stimulation.

“Severe drought conditions in South Texas and overpopulation are putting a lot of strain on freshwater resources,” Dennis Naeger, water management marketing director for Tetra Technologies Inc., told attendees at the Hart DUG Eagle Ford conference in San Antonio. “We have to find alternative water sources – brackish water, non-potable water, municipal effluent water, flowback and produced water. That’s how we reduce demand for fresh water resources.”

Tetra Technologies is a diversified oil and gas services company that provides turnkey services on water for oil and gas activity, compression-based production enhancement services, production testing services and well completion fluids and services. The company, based in The Woodlands, operates both onshore and offshore.

“Doing slickwater fracs using fresh water only, that’s fairly easy,” Naeger said. “It is conventional technology for the most part. Transfer, storage – the means to do that – is very simple.” The issue gets more complex when reusing produced water, flowback water, or highly contaminated water sources. Beyond the treatment issues, handling and storing water, blending it, and transferring it to the next well site creates challenges.

According to Naeger, that extra complexity means oil and gas operators should be proactive in developing a water management strategy, including an assessment of how a company is managing its water, an investigation of what alternative supplies are available, and a review of blending targets in oil and gas drilling. Naeger said the process should include a full review of all issues involved and identification of potential risks. Once a company defines its strategy, the next step is looking at the technologies and services to meet blending targets and manage risk – and cost.

“Preserving Texas water supplies requires better technology and operational excellence because of the increased risks to the environment of doing this,” Naeger said. Evidence of the growing focus on the use of alternative sources is found in the fact that the fastest growing division at Tetra Technologies is water management services. “We are investing more capital in water services than any other division,” he said.

Integrating water re-use or incorporating lower-quality water into the oil and gas drilling process involves multiple steps, and each has its own technology and best practices. Blending those steps into the best workable solution for a specific program is the challenge.

Solutions typically represent different points along a spectrum. For example, operators can employ ready-built above-ground storage impoundments holding 10,000 to 500,000 barrels. These containers are portable and can be moved and reassembled on new sites. But alternatives include excavating pits with proper linings.

Similarly, transferring water can involve temporary flowlines, poly pipe, jointed and fitted pipe, or flexible hoses. The latter is of interest when transferring highly contaminated produced water in order to avoid leaks and damage to the surface environment or fresh water sources.

Perhaps the most complex aspect is commingling water of varying qualities from flowback or produced water and producing a homogenous frac fluid. It is better to provide blended and treated waters ready to go rather than treating the water once it is in the working tanks.

“The water needs to be blended,” Naeger said. “It doesn’t need to be injected into a manifold and into the working tanks and treated there because you need to provide a homogenous consistent frac fluid. This optimizes your treatment (and) optimizes the overall frac fluid quality going into the blender, and that makes for a better completion.”

Tetra markets a blending manifold that is placed between the water source and the working tanks. The trailer-mounted unit is easy to deploy and can also mix in additives such as biocides that assist the water-treatment process. Additionally, the unit can provide real-time measurements on water quality, enabling additives to be injected on the fly and providing clean, scale-free frac fluid. The blending manifold replaces the older and less efficient system of sending water samples to a lab and waiting a week or two for results.

“It’s not business as usual,” Naeger said. “Developing a water-management strategy to incorporate water reuse and alternative water supplies requires operational excellence and better technology.”

Biocides and Scale Inhibitors

The oil and gas industry is getting pro-active on water re-use issues, according to Michael West, business development manager for BWA Water Additives, and that has elevated the sector into the spotlight for water-treatment services. Previously, water-treatment services and chemical additives were focused on manufacturing and industrial uses or in desalinization efforts in places like the Middle East.

“What I have seen in the last couple years is this paradigm shift where E&P companies are putting in water-management groups,” West said. “We never saw that before. They always relied on the service companies to manage their water for them. We saw it first in the Barnett, then in the Marcellus, where they had such severe EPA regulations that we had to look at how to reuse water.”

Consequently, the oil and gas industry is rapidly changing its approach to water use.

“Water impoundment pits -- we didn’t see those a few years ago because we weren’t using the water for fracing,” West said. “We were actually disposing all the water that was produced in disposal wells.”

However new solutions like impoundment pits create issues in regard to water treatment.

BWA Water Additives is a privately held specialty chemical supplier of water additives that operates in 90 countries. The roots of the business stretch back 40 years to a handful of chemical companies. Today, BWA specializes in oxidizing biocides for industrial cooling water and the paper industry as well as polymers and non-oxidizing biocides for industrial cooling water and desalination. The company has moved into the oil and gas business. West spoke at the DUG Eagle Ford conference in San Antonio.

In oil and gas, water additives are used as microbiocides and antiscalants during fracture stimulation, cement squeezing, and oil and gas production. Microbiological growth impacts surface water impoundments or pits in the form of algae. Hydraulic fracturing operations test the limits of biocides because of high temperatures and pressures, while biofilm is an issue in pipelines. Scale impacts production, and pipelines and can have deleterious affects on valves and other well site equipment.

The industry has been able to use both oxidizers and non-oxidizers to date as microbiocides. Each has advantages and disadvantages. Both can provide fast kill, but each can be corrosive and both display varying degrees of stability. Cost is an issue as well in determining whether to use oxidizers or non-oxidizers. BWA recently began marketing Tributyl Tetradecyl Phosphonium Chloride, or TTPC, in the oil patch.

“This is the first new biocidal additive approved by the EPA in the last 10 years,” West said. “It’s not an ordinary biocide. We’ve used it for a long time in the cooling water industry. It has corrosion inhibition properties. It is synergistic with the oxidizing biocides we normally use in the cooling industry. It is safe for handling and is not a skin sensitizer. Those attributes have been very well received by the oil industry.”

TTPC is an ampipathic molecule that disrupts the bacteria cell membrane. TTPC controls algae in significantly lower doses than competing glutaraldehydes, West said, and TTPC can achieve a complete kill as a biocide in hydraulic fracturing in one hour at dosages that are 75% less than glutaraldehydes, which normally require four hours to be effective.

Industry interest in water additives also includes scale inhibition technologies.

“What we’ve seen happening over the past two to four years is higher TDS (total dissolved solids) in frac water re-use,” West said. “(We’ve seen) higher well temperatures, complex water systems that include elevated levels of iron and calcium. If you have seen any waters from the Bakken, they are pumping liquid salt out of the well and they are needing to get something downhole near a well bore that they can treat these incredibly complex systems.”

The challenge for the industry is choosing which scale inhibitor to use. Scale buildup changes as pressure changes. Scale is harder to treat. Solutions include a threshold scale inhibitor and crystal growth modifier.

“In a threshold inhibitor, you are disrupting the cluster before it can nucleate and form a crystal and start attaching,” West said. “Phosphenates and low molecular weight polymers work well, but once they get past the threshold limitation and the crystal forms, they fail drastically.”

BWA is working with a United Kingdom-based company to distribute Phosphino polycarboxylic acid (PCA), a biodegradable specialty polymer that has been used in the North Sea and Europe. PCA is a crystal growth blocker that performs better in changing pressure and higher temperature regimes at lower relative treatment volumes than standard scale inhibitors and lasts longer before it breaks down.

Contact the author, Richard Mason, at rmason@hartenergy.com.

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