This dataset contains compositional data on 17 produced water samples from hydraulically fractured unconventional oil wells completed in the Middle Bakken and Three Forks Formations. The oil wells are located in five different wellfields across the Williston Basin. Specific gravity, conductivity, temperature, pH and oxidation-reduction potential for each sample was measured in the field. Ions (B, Li, Cl, Na, Br), biomarkers (Pristane /n-C17 and Phytane /n-C18), glycol ether compounds, major ions, as well as radium (Ra-228/Ra-226), boron (δ11B), oxygen (δ18O) and hydrogen (δ2H) isotopic ratios were analyzed in the lab. Well profiles are provided to increase understanding of the produced waters compositions in the context of the depth of the well, age of the well, the time since hydraulic fracturing, the amounts of water injected and produced since hydraulic fracturing, the hydraulic fracturing treatment fluid types injected.