Integrated Approach to Optimize Flowback in Multi-stage Hydraulically Fractured Wells

The key goal of the work is to optimize the process of flowback in wells after multi-stage hydraulic fracturing in fields with unconventional oil reserves. The procedure for selecting the optimal flowback operation is to tune the model based on field data, adapt the fracture cleanup model using sensitivity analysis on input parameters, and select the most effective scenario of bottomhole pressure decreasing. This article can be separated into three parts. The first one consists cleanup model description. The second one shows sensitivity analysis of the results of flowback modeling with respect to key input parameters. The last one includes optimization and history matching methods to fit the modeling and field data. Model adaptation to field data is carried out using iterative Newton's method (MSE < 10% for the first 30 days of flowback). The results of model adaptation to the well in unconventional hydrocarbon reservoir of Western Siberia showed that several additional physical phenomena have to be considered as compared to those describing flowback in traditional terrigenous reservoirs including increased permeability of near-fracture reservoir due to presence of natural fractures and oil-water emulsion. Our preliminary results show that the developed flowback model can be used to describe flowback in unconventional wells both qualitatively and quantitatively.