One of the few statements both sides of the subject of drilling for oil and gas utilizing hydraulic fracturing can agree on:

Getting either/both fossil fuels out of the ground takes an immense volume of water.

How much water per well depends on a number of factors, including rock formation, the operator, whether the well is vertical or horizontal, and the number of well stages fractured.

Some water is recycled from fluids produced by the well, so net consumption might be smaller at sites that recycle, a number constantly growing.

Water usage per well varies

Bottom line: Water use per well can be anywhere from roughly 1.5 million gallons, to about 16 million gallons for a fracked, horizontal well.

The amount of water used per well for fracking surged by up to 770% between 2011 and 2016 in all major US shale gas- and oil-producing regions, a Duke University study found.

The volume of flowback and produced water new wells generated during their first year of operation also increased, by up to 1,440%.

If this rapid intensification continues, fracking’s water footprint could grow by up to 50-fold by 2030, the Duke study opines.

Water from the ground as a byproduct of oil drilling

Two new studies led by researchers at the University of Texas (UT) at Austin (Texas) conclude enough water will come from the ground as a byproduct of oil production during coming decades to “theoretically” overcome the need to use fresh water for fracking in many U.S. oil-producing areas.

The studies also conclude water quality issues and the potential costs involved mean the best use of waste water is to keep the water in the oilfield.

“The most obvious solution with the lowest risk (in determining what to do with waste water) would be to close the water loop by reusing produced water within the oil and gas sector to support hydraulic fracturing,” Bridget Scanlon, lead author of both studies and a senior research scientist with the UT Bureau of Economic Geology, told Kallanish Energy.

“They (producers) have changed the water chemistry required to hydraulically fracture wells and they can reuse the produced water for hydraulic fracturing with minimal treatment (clean brine).”

Quantifying produced water vs need when fracking 

The first study was published in Environmental Science and Technology Feb. 16. It quantifies for the first time how much water is produced with oil and natural gas operations compared with how much is needed for hydraulic fracturing.

The authors also project water demand for hydraulic fracturing needs and produced water over the life of the oil and gas plays, which span decades.

The researchers analyzed water-related sustainability of energy extraction focusing on:

• Meeting rapidly rising water demand for hydraulic fracturing (HF)
• Managing rapidly growing volumes of water co-produced with oil and gas (produced water, or PW).

“We analyzed historical (2009–2017) HF water and PW volumes in roughly 73,000 wells and projected future water volumes in major U.S. unconventional oil (semiarid regions) and gas (humid regions) plays,” the study’s authors state.

“Results show a marked increase in HF water use, depleting groundwater in some semiarid regions (for example, by ≤58 feet per year in the Eagle Ford Shale play).”

More produced water from oil plays than gas plays

“Another thing we were not aware of beforehand was that oil plays produce much more water than gas plays, with the Permian producing up to 50 times more water than the Marcellus play in 2017,” Scanlon told Kallanish Energy.

Water issues related to both fracking water demand and produced water supplies may be partially mitigated by closing the loop through “reusing PW for HF of new wells,” the study reports. Many producers already have put such methods to use, recycling millions of gallons of water.

But projected produced water volumes exceed fracking water demand in semiarid plays, such as the Bakken (2.1 times) and the Midland (1.3 times) and Delaware (3.7 times) basins, all oil plays, with the Delaware accounting for roughly 50% of projected U.S. oil production.

“Therefore, water issues could constrain future energy production, particularly in semiarid oil plays,” the study purports.

Other uses for produced water

The second study was published in Science of the Total Environment Feb. 3. It assesses the potential for using the water produced with oil and natural gas in other sectors, such as agriculture.

It included researchers from New Mexico State University, The University of Texas at El Paso and Penn State University. It shows current volumes of produced water are relatively small compared with irrigation water demands and will not solve water scarcity issues.

“There is increasing interest in beneficial uses of large volumes of wastewater co-produced with oil and gas extraction (PW) because of water scarcity, potential subsurface disposal limitations, and regional linkages to induced seismicity,” according to the study.

“Here we quantified PW volumes relative to water demand in different sectors and PW quality relative to treatment and reuse options for the major U.S. shale oil and gas plays.”

One year vs one day

PW volumes from these plays totaled roughly 160 billion gallons in 2017. One year of PW is equal to approximately 60% of one day of freshwater use in the U.S., according to the study.

For these plays, the total irrigation demand exceeded PW volumes by roughly 5 times, while municipal water demand exceeded PW by approximately 2 times.

“If PW is reused for fracking within the energy sector, there would be no excess PW in roughly half the plays because HF water demand exceeds PW volumes in those plays,” the study states.

Seven times saltier than seawater

The researchers state produced water quality can be highly saline (salty), with median total dissolved solids up to 255 grams per liter (g/L) in the Bakken, roughly 7 times saltier than seawater.

“Intensive water treatment required for PW from most unconventional plays would further reduce PW volumes by at least 2 times,” according to the study. “Desalination would also result in large volumes of salt concentrates, equivalent to approximately 3,000 Olympic (-size) swimming pools in the Permian Delaware Basin in 2017.”

While water demands outside the energy sector could accommodate PW volumes, much lower PW volumes relative to water demand in most regions would not substantially alleviate water scarcity.

However, large projected PW volumes relative to fracked water demand over the life of the play in the Delaware Basin may provide a substantial new water source for beneficial use in the future.

Large knowledge gaps in produced water quality, lack of appropriate regulations, and economic factors currently preclude beneficial uses outside the energy sector in most regions.

An increasing challenge

Dealing with water issues has become increasingly challenging with oil and natural gas development in unconventional shale basins/plays, the UT researchers state.

The contributing researchers said the studies can help inform significant public policy debates about water management related to oil and natural gas production in Texas, Oklahoma, New Mexico and other parts of the country, according to Scanlon.

“The water volumes that are quoted vary widely. That’s why we did this study,” she said. “This really provides a quantitative analysis of hydraulic fracturing water demand and produced water volumes.”

The research looked at eight major plays across the U.S., including the Permian (Midland and Delaware basins), Bakken, Barnett, Eagle Ford, Fayetteville, Haynesville, Marcellus and Niobrara plays.

The scientists used historical data from 2009 to 2017 for all plays, and projections were developed for the life of the oil plays based on the technically recoverable oil using current technology.

Working on another study

Scanlon told Kallanish Energy she and her fellow researchers are currently doing a case study of the Permian Basin to “zero in on environmental impacts, particularly with respect to water resources (surface water and groundwater) from groundwater use for hydraulic fracturing, subsurface disposal capacity to determine if we can accommodate the projected produced water volumes.”

“We also plan to characterize the chemistry of produced water to determine the source of the produced water and also the implications for treatment of produced water for potential use outside of the oil and gas sector.”

This post appeared first on Kallanish Energy News.