HOW DOES WATER USE FOR HYDRAULIC FRACTURING OF UNCONVENTIONAL SHALE OIL COMPARE WITH SHALE GAS AND WITH CONVENTIONAL OIL PRODUCTION?

Diverging oil and gas prices with 4–6 times higher oil prices/unit of energy has shifted hydraulic fracturing (HF) towards more oil-rich shale plays. Here we compare HF water use for unconventional oil versus gas production in the Texas Eagle Ford Shale (top US shale oil producer) and with HF in the Bakken oil play and with water use in US conventional oil production. We found average HF water use in the Eagle Ford in oil zones is similar to that in gas zones per well (4.6–4.8 million gallons water/well; 2009–mid-2013) and per length of lateral or horizontal well length (~1 mile long laterals, ~900–1000 gal water/ft. of lateral). Variations in HF water use/unit of energy reflect differences in energy production to date: higher HF water use in the oil zone (water/oil volume ratio of 1.5, 11 gal/million British thermal units, Btu) than in gas/condensate zones (water/oil equivalent volume ratio of 0.6, 4 gal/million Btu). Mean HF water use in the Bakken is about half of that in the Eagle Ford on a per well basis (1.8 million gal water/well, 2005–mid 2013) and about a quarter of that in the Eagle Ford per length of lateral (220 gal water/ft. of lateral) because of longer laterals in the Bakken (~2 miles long). Average water use per unit of energy produced to date in the Bakken (water/oil volume ratio of 0.4, 3 gal/million Btu) is about two thirds of that in the Eagle Ford. Water use per unit of energy for unconventional oil production should decrease throughout the well lifetime resulting in water/oil volume ratios of 0.34 for the Eagle Ford and 0.20 for the Bakken. Water use for unconventional oil based on production to date (water/oil volume ratio of 0.4–1.5, 3–11 gal/million Btu) is generally within the lower range of previous estimates of fresh (non-produced) water use for U.S. conventional oil (water/oil volume ratio of 0.5–5, 4–36 gal/million Btu), indicating that increased water use for hydraulic fracturing is related to much higher oil production.