Texas shale plays among biggest water users – USGS study

New study shows water volumes used in fracking varies widely across country, Texas shale formations are highest

A new study from the US Geological Survey finds that drillers in the Texas shale formations of Eagle Ford, Barnett and Haynesville-Bossier are among the heaviest water users in the American oil patch.

This map shows the average water use in hydraulic fracturing per oil and gas well in watersheds across the United States. Source: US Geological Survey.

The amount of water required to hydraulically fracture oil and gas wells varies widely across the country, from as little as 2,600 gallons to as much as 9.7 million gallons per well.

“One of the most important things we found was that the amount of water used per well varies quite a bit, even within a single oil and gas basin,” said USGS scientist Tanya Gallegos, the study’s lead author.

“This is important for land and resource managers, because a better understanding of the volumes of water injected for hydraulic fracturing could be a key to understanding the potential for some environmental impacts.”

The watersheds where the most water was used to hydraulically fracture wells on average coincided with parts of the following shale formations:

• Eagle Ford (within watersheds located mainly in Texas)
• Haynesville-Bossier (within watersheds located mainly in Texas & Louisiana)
• Barnett (within watersheds located mainly in Texas)
• Fayetteville (within watersheds located in Arkansas)
• Woodford  (within watersheds located mainly in Oklahoma)
• Tuscaloosa  (within watersheds located in Louisiana & Mississippi)
• Marcellus & Utica (within watersheds located in parts of Ohio, Pennsylvania, West Virginia and within watersheds extending into southern New York)

The study found that from 2000 to 2014 median annual water volume estimates for hydraulic fracturing in horizontal wells had increased from about 177,000 gallons per oil and gas well to more than 4 million gallons per oil well and 5.1 million gallons per gas well. Median water use in vertical and directional wells remained below 671,000 gallons per well. For comparison, an Olympic-sized swimming pool holds about 660,000 gallons.

Shale gas reservoirs are often hydraulically fractured using slick water, a fluid type that requires a lot of water. In contrast, tight oil formations like the Bakken (in parts of Montana and North Dakota) often use gel-based hydraulic fracturing treatment fluids, which generally contain lower amounts of water.

Horizontal wells are those that are first drilled vertically or directionally (at an angle from straight down) to reach the unconventional oil or gas reservoir and then laterally along the oil or gas-bearing rock layers. This is done to increase the contact area with the reservoir rock and stimulate greater oil or gas production than could be achieved through vertical wells alone.

Horizontal wells also generally require more water than vertical or directional wells. In 52 out of the 57 watersheds with the highest average water use for hydraulic fracturing, over 90 per cent of the wells were horizontally drilled.

Although there has been an increase in the number of horizontal wells drilled since 2008, about 42 per cent of new hydraulically fractured oil and gas wells completed in 2014 were still either vertical or directional.

The ubiquity of the lower-water-use vertical and directional wells explains, in part, why the amount of water used per well is so variable across the United States, according to the study.

The findings, released June 30, were the first national-scale analysis and map of hydraulic fracturing water usage. The USGS study has been accepted for publication in Water Resources Research, a journal of the American Geophysical Union. USGS researchers used data on more than 81,000 wells across the U.S. collected from IHS Energy.