A new study from the University of Arizona and the University of Saskatchewan finds that conventional oil and gas drilling has a greater impact on groundwater than does unconventional drilling.

Unconventional drilling pulls reserves from the ground using horizontal wells combined with hydraulic fracturing (fracking). Conventional drilling, using vertical wells, also may use fracking to produce oil and gas.

The amount of water injected and produced for conventional oil and gas production exceeds that associated with unconventional oil and gas production “by well over a factor of 10,” said University of Arizona’s Jennifer McIntosh, professor and hydrogeologist.

McIntosh and fellow researcher Grant Ferguson from the University of Saskatchewan analyzed the volumes of water that operators injected underground. They tested how various production activities change pressures and water movement underground, and how those activities could contaminate groundwater supplies. They compared data from conventional and unconventional wells, McIntosh said.

The research culled data from a variety of sources, including state agencies, to expand on the available published scientific studies, which only cover a few producing regions.

McInstosh and Ferguson analyzed data from California, Oklahoma, Ohio, the Permian Basin and the Western Canadian Sedimentary Basin.

The purpose of the new study was to better understand what activities pose challenges to water security. While much attention has been paid to the impact of unconventional drilling and fracking, it doesn’t represent the entire relationship between oil and gas production in North America and groundwater security, said a spokesperson for the University of Arizona in reference to the study.

Global Water Futures, a broad University of Saskatchewan-led research project that focuses purely on research and risk management for fresh water security, funded the latest research, which was published in the journal Groundwater.

“If we want to look at the environmental impacts of oil and gas production, we should look at the impacts of all oil and gas production activities, not just hydraulic fracturing,” said McIntosh.

How oil and gas production affects water security, particularly in places where water supplies are already stretched, as in the Permian, has been an area of focus for regulators as well as industry service providers.

Overall, the produced water market in the United States may reach 4 million barrels/day by 2025, according to Raymond James & Associates Inc. Disposal and treatment costs for water typically run around $1.00/barrel, which means there is a $12 billion market in the Permian alone, the biggest market with more than 60% of the country’s produced water, analysts said.

To that point, Solaris Water Midstream LLC said in July it had begun to develop a second produced water recycling facility in the Permian Basin.

Solaris has ramped operations at its expanded Lobo Ranch Produced Water Recycling and Blending Center, a large-scale produced water recycling and nonpotable water blending facility in Eddy County, NM. It also has begun to develop the Bronco facility in Lea County, NM.

But for the public, the water issue is two-fold — operators sometimes turn to fresh water in lieu of insufficient recycled water supplies for production activities, which stretches water supplies, but then the disposal of produced water also has the potential to contaminate existing groundwater, further impinging water supplies.