Geochemical Fingerprinting of Produced Water for Enhanced Well Control and Fracturing Efficiency

The geochemical fingerprinting of produced water has been identified as a practical tool for operational applications in the petroleum industry. Provenance studies of produced water are essential to trace flow dynamics and reservoir compartmentalization in petroleum systems and to quantify fluid recovery rates from unconventional fracturing. Due to the fact that recovered oilfield water samples are frequently contaminated by operational fluids (i.e., oil-based mud, water-based mud, completion brines or stimulation fluids), representative samples for reservoir fluids have to be filtered from the geochemical data set of produced water. Besides the routine analysis of major elements (Na, Ca, Mg, K, Cl, SO₄, HCO₃), an enhanced geochemical monitoring program with selected minor and trace elements (i.e., B, Ba, Li, Sr), environmental isotopes (i.e., delta²H, delta¹⁸O, ⁸⁷Sr/⁸⁶Sr) and radiogenic isotopes (i.e., ³H, ¹⁴C) can provide in-depth information on the provenance of recovered oilfield water. Provenance studies of flowback water from hydraulic fracturing assets represent an enhanced method to assess the efficiency of the fracturing process by quantifying the recovered volume of originally injected fracturing fluid during the post-fracturing phase. The combination of gas recovery rates with geochemical flowback efficiency resulted in a practical tool to characterize the type and complexity of natural and induced fractures. Two cases studies showed that the combination of high gas recovery rates with low backflow efficiencies imply the presence of a complex system of natural and induced fractures. As a practical outcome, geochemical fingerprinting of recovered fluids can improve operational strategies for performed fracturing assets by avoiding water-pay zones, minimizing the amount of required fracturing fluids for injection purposes, and economizing the recycling process for recoverable flowback fluids. For the drilling of exploration or production wells, the presence of overpressured formations with a sudden water cut can frequently cause a technical challenge during well cementation. The design of a filtered geochemical database with regional fingerprints of formation water and groundwater zones is essential to identify the specific interval of water breakthrough for well plugging solutions. The routine geochemical analysis of reference water types, such as supply water and mud filtrate from the drilling process, is mandatory to quantify the potential flowback of applied drilling fluids.