Abstract
We performed numerical modeling of four refrac datasets – three from the Bakken and one from the Midland Basin. For each, history matching was performed to production data and diagnostic measurements from prior to the refrac. Then, the model was used to ‘blind predict’ the performance of the refracs. In the final step, the model prediction was compared with the actual production, and if needed, the inputs were updated to match the observed data. The simulations were performed with a fully integrated hydraulic fracturing and reservoir simulator. In a single simulation, the model incorporates the initial fracturing treatment(s), production, the refrac, and subsequent production. The integrated approach is advantageous for refrac because: (a) fluid crossflows into the original fracs during the refrac, resulting in multiphase oil/water/gas flow occurring simultaneously with fracture reopening, propagation, and proppant placement in the original fractures, and (b) the initial conditions of the refrac depend on the prior fracturing and production. After comparison with the field data, the blind refrac predictions were found to have good accuracy. On average, the refracs achieved a 26% uplift in the wells’ cumulative production after one year. The smallest increase was 10%, and the largest increase was 57%. The average prediction mismatch in one-year cumulative production uplift was 3.7%. After unblinding, model recalibration was performed by modifying a parameter that controls the strength of crossflow outside casing.
1. Introduction
Refracturing provides a relatively small, but meaningful, contribution to production in unconventional resources (Lindsay et al., 2016; Morales et al., 2016; Brady et al., 2017; Dalkhaa et al., 2022; Bryan et al., 2023; Velasquez et al., 2023; Cui et al., 2023; Brinkley et al., 2023; Barba et al., 2024). Most commonly, refracturing is performed by cementing a new liner inside the original casing and performing multistage plug and perf completion. Less commonly, refracs are bullheaded by pumping directly from the surface without utilizing any zonal isolation. Hybrid options are also available (Eichinger et al., 2023). Refracs may also be used as ‘protection’ fracs to reduce the impact of negative parent/child interactions from infill wells (Miller et al., 2016; Rezaei et al., 2017).
