Inter-well Fracture Driven Interaction (FDI) has gained visibility as it could lead to significant performance impacts on both parent and child well production in unconventional reservoirs. Various strategies, including optimizing well completion design of child wells (e.g., varying slurry volume per cluster), optimizing well spacing, stage spacing, cluster spacing and fracture sequencing, as well as protecting parent wells (e.g., pre-loading, continue flowing), etc., have been tried in the industry to mitigate the negative impact of FDIs on production performance. To quantify the expected benefit of each mitigation strategy, it is critical to understand the impact of the different mitigation strategies on the production performance in different well scenarios and reservoir settings.
A series of numerical modeling of FDIs using a coupled hydraulic fracturing propagation, reservoir flow, and geomechanics tool has been carried out. The tool couples hydraulic fracture simulation with geomechanics, hence it can capture the stress change due to the depletion at the parent well as well as the pressure response and water cut response at the parent wells due to FDI. Two field case studies have been conducted in two different basins. In both field studies, a history match of parent and child well production is first conducted to calibrate the model setup. This is a crucial step, as the numerical tool requires inputs which cannot be obtained with independent measurements. Then, a sensitivity study is performed on various key parameters, including well spacing, level of depletion at the parent well, slurry volume per cluster, proppant intensity, and fracture sequencing to understand their impact on parent and child well production. FDIs are impacted by complex geomechanical and flow damage mechanisms. The FDI mitigation strategies and field development optimization need to be considered together.
The numerical study shows that for the basins we have studied, the FDI and some mitigation strategies have minimal impact on the long-term parent well productions. However, parent depletion (volume and areal extent), well spacing, and child fracture asymmetry greatly impact child well production due to FDI. Learnings from this study, integrated with other studies provide guidance to make the appropriate business decisions regarding FDI mitigation, completion design optimization and field development planning. Comparison between the two field cases also demonstrates that different basins behave differently and might require different mitigation strategies and optimum designs.