SOURCING UINTA BASIN FLOW-BACK WATER TO MAXIMIZE WELL YIELD USING ISOTOPIC FINGERPRINTING

Flow-back water is the combination of various mobilized formation fluids that come to the surface with oil during pumping. Uinta Basin petroleum companies estimate profits based on the ratio of the amount of flow-back water to oil produced. By reducing the amount of flow-back water produced profits will increase. Models and estimates of flow-back water are made with the best available data prior to drilling. If modeling determines that a target will produce a significant amount of flow-back water, it will not be drilled. The current amount of flow-back water that is coming from producing wells in the Uteland Butte Member of the Green River Formation has increased, surpassing all models and maximum estimates. This unexpected increase in the amount of flow-back water production has strained the budgets of companies by reducing the amount of oil produced and increasing remediation costs for flow-back water. Here we employ δ¹⁸O, δ²H, and ⁸⁷Sr/⁸⁶Sr to characterize the unique fingerprints of each individual flow-back water from multiple wells across the Uinta Basin. Additionally, we use these isotopic systems to calculate mixing trends between various water sources that could contribute to flow-back waters (e.g. meteoric water, connate water, etc.). Time series sampling will be used over the course of one year from four new individual wells. These four wells recently completed in the Uteland Butte Member and their isotopic composition will be tested. We will use the results of these isotopic analyses to test the hypothesis that flow-back water should evolve over time as increasing invasion of formation fluid occurs. The time series data, generated from the new oil wells, will be compared to local and regional meteoric waters, the original supply waters, flow-back water from above and below the target zone, and to other aquifers that exist along the well bore. This will assist in locating the source of the increased flow-back water based on its unique isotopic and chemical fingerprints. Once the source of the increased amount of flow-back water is determined, oil production from the Uteland Butte can avoid it. Assessment of the stable isotopic and elemental geochemistry data of flow-back water from four new oil wells in time series will allow for the development of a subsurface connectivity profile in the Uteland Butte Member.