For eons, Mother Nature has been purifying water. The Earth’s hydrological cycle is one of the wonders of nature and is key to sustaining life on our planet. Yet today, lack of water has become a major challenge to oil and gas producers and their service company partners who perform hydraulic fracturing services.

Bulk tanks and onsite piping are manufactured from readily available, non-corrosive plastic.

In case anyone missed high school physics or slept through science class, the earth’s surface is about 70% covered with water. The sun causes continual evaporation of this seawater, and the water vapor ascends into the atmosphere, leaving the salt and any other impurities behind. As the pure water vapor rises, it is cooled and condenses into rain, which ultimately falls to earth, irrigates the land, and flows back to the sea, where the cycle is repeated.

What if the earth’s hydrological cycle could be replicated, except on a micro-scale?

New Mexico-based Altela Inc. has developed a modular water purification system based on the principle of the hydrological cycle. It is called, appropriately, AltelaRain.

One of the beauties of the Earth’s hydrological cycle is that it is completely indiscriminate — it evaporates water from any source; from lakes and rivers to seawater to open sludge pits. And the water vapor is pure because the process leaves all the nasty stuff behind. This quality is replicated in the Altela system, so it is capable of recovering pure, fresh water from produced water, from recovered frac fluid, or virtually any fluid containing a water phase.

Portable units can be spotted at wellsites to reclaim produced water or frac flow-back water, or several units could be co-located strategically to form a “water plant” and produce large volumes of clean water to fill fleets of frac tanks. Advantages include elimination of high disposal costs for operators, who must either pump the water back into a deep saltwater aquifer or treat it before it can be used for irrigation or dumped. The relatively low volume of contaminants recovered from the purification process can be disposed of conventionally. The system is currently in use in the San Juan and Piceance Basins, helping to reclaim formation water coproduced from gas wells. Recently, a unit was installed in Pennsylvania to reclaim water from producing units exploiting the Marcellus Shale.

Easily transported to any site by standard container carrier, units can be spotted strategically as needed.

How clean is it?

Outflow from the units is clean and green. In the system’s inaugural field test, conducted in New Mexico using real oilfield produced water, total dissolved solids (TDS) were reduced 99.8% from 41,700 mg/L to 106 mg/L. Chloride was reduced 99.8% from 25,300 mg/L to 59 mg/L. Benzene levels were reduced from 450 ?g/L to non-detectable. Effluent from similar tests was certified pure enough to outflow into the Colorado River by the State of Colorado and was the first ever treatment solution certified for discharge onto tribal grazing land by the Navajo Nation. According to Altela, the treated water exceeds the tough new standards that will be imposed by the State of Pennsylvania later this year of TDS less than 500 mg/L. Confident executives demonstrate the efficacy and safety of the process by gleefully swigging the effluent as it comes right out of the treatment unit.

The processing module uses hundreds of thin plastic chamber sheets to mimic the natural distillation process.

How it works is a microcosm of nature

At the heart of the system is a complete hydrological cycle encapsulated in a module approximately 24 in. square by 80 in. high (Figure 1). The modules contain hundreds of cells, each consisting of an evaporation chamber and a condensation chamber separated by a micro-thin, non-corrosive, thermally conductive wall that is water-impermeable. Unlike nature, where the evaporation takes place hundreds or thousands of miles from the condensation (rain) site, the processes are separated by a micro-thin membrane in the Altela system. Produced water or frac effluent is piped into the top of the module along with low-temperature or waste heat. This heat can come from just about any source — engine exhausts, casinghead gas combustion, solar-powered electrical heaters, or directly from a gas wellhead. The heat is used to accelerate the evaporation process. The water vapor thus produced exits the top of the evaporation chambers and enters the condenser, where it coalesces into water droplets, ultimately exiting out the bottom into a flowline. On the evaporation side, concentrated brine waste flows out, where it is sequestered and disposed of.

Modules are ganged into a standard, stackable, 45-ft (13-m) shipping container for easy, economical transportation to a field site (Figure 2). Each container has enough modules to eliminate more than 100 b/d of brackish water. Units are easily upscalable, and the company recently announced plans to build stationary plants in the Marcellus to treat more than 5,000 b/d of fresh water.

Nature is simple. So is the Altela process. No exotic materials, inputs, or filters are required. Module components are constructed of inexpensive, non-corrodible plastic (Figure 3) rather than costly corrodible metals like other technologies use. Since no pressurization is required, piping and tanks can also be manufactured from standard inexpensive plastics such as polyvinyl chloride (PVC), resulting in low capital costs. Operating costs are also low because Altela’s non-pressurized system requires no pressure pumps and therefore uses virtually no electricity. And as efficient as Mother Nature is, the Altela process is even more so: it can treat three gallons of water for the energy that Mother Nature uses to evaporate one gallon.

This schematic of a thermal distillation treatment module illustrates the process. (All images courtesy Altela, Inc.)

Economic benefits are significant

Operators who have used the system reckon that nine out of 10 wastewater hauling truckloads are eliminated because the fresh, distilled water can be reused on the lease or released as irrigation water. The system runs unattended and uses only low-temperature heat from the wellhead, solar panels, or waste heat. And there are no high-pressure or high-temperature components that might constitute a safety risk. No corrosive or toxic chemicals are used in the process, reducing cost while also adding to safety. No job is too tough for the system — it is capable of treating liquids with TDS concentrations in excess of 100,000 ppm. Units can be transported, dropped off, and subsequently picked up at field locations by any standard medium-duty container carrier truck. The waste stream of concentrated brine is 20% or less of the total water treated depending on water TDS and can be disposed of in any standard disposal well; no special permits are required.

Transcends reverse osmosis techniques

Operating on the natural principle of thermal distillation, the Altela system decontaminates saline and otherwise polluted water using a completely different system than the reverse osmosis (RO) system commonly used to produce drinking water from seawater. Reverse osmosis systems use thin permeable membranes that can foul, require high maintenance, or need frequent replacement. Though effective in seawater applications where the main salt is NaCl (table salt) and concentrations do not exceed 35,000 ppm, they have repeatedly failed in oil and gas applications where the water contains a mixture of far more difficult salts and the concentration is often well above this 35,000 ppm upper limit of RO.

Conversely, the Altela technology follows the natural process of the earth’s hydrological cycle, effortlessly and continuously producing clear, clean water for reuse in fracturing, for mixing drilling mud, or for any freshwater requirement at the field site. Some operators have used the water as part of their “good-neighbor” programs, supplying nearby farmers and ranchers with water for crops and livestock. It is estimated that more than 5 Bbbl of brackish formation water is produced every day from America’s oil and gas wells. Why waste money transporting and reinjecting this water if it can be treated for reuse on the surface with 90% efficiency? In some locales, operators are having difficulty acquiring sufficient water rights to support their drilling and completions programs. Having access to thousands of barrels of desalinated produced water could alleviate this problem altogether. Interestingly, the water shortages are most pronounced in the Northeast rather than the desert Southwest where one would normally associate water shortages. The more densely populated areas with their industrial requirements along with farm and recreational use have put a strain on water supplies in areas most people think are lush with streams, rivers and lakes.

Maybe it is time to let nature take its course. It will anyway.