Sources of variability in flowback and produced water volumes from shale oil and gas wells

•The focus is the Wattenberg field, Denver-Julesburg basin (USA).•Sources of variability in water production are examined.•It provides factors for consideration when predicting water production in the future.

Wastewater from shale oil and gas wells is an issue that has received significant attention although limited research has been conducted on the variability of water production from hydraulically fractured wells. In this paper, sources of variability in flowback and produced water volumes from horizontal oil and gas wells were examined and correlations established. Horizontal wells in the Denver-Julesburg basin operated by Noble Energy were studied and results show that water production varies with time, location and wellbore length as expected. Additionally, production volume variation with fracturing fluid type and water source (fresh versus recycled) was explored. Results indicate that both of these variables should also be considered when developing a general model for water production. A guar based frac fluid resulted in greater water production when compared to a cellulose-derivative based fluid. Finally, wells fraced with a fresh water based fluid had significantly greater produced water volume than geospatially-paired wells with a 1/7-recycled/fresh blend based fluid.