Inter-well Fracture Driven Interaction (FDI), aka Frac Hit, has gained visibility as more high intensity events (pressure increase in parent wells). Severe production performance impact (parent and child wells) are observed in depleted and tightly spaced wells in unconventional reservoirs. Various strategies, including water pre-loading in parent wells, adjusting well completion design of child wells, optimizing development plans, etc., have been tried in the industry to mitigate the negative impact of FDIs on production performance. However, mixed results have been observed in some pilot tests utilizing a water pre-loading mitigation strategy. Hence, it is critical to understand the driving mechanisms and key parameters impacting pre-loading performance in order to quantify the expected benefit of pre-loading in different well scenarios and optimize the pre-loading design.
A novel integrated and coupled geomechanics / fluid flow / fracturing propagation modeling workflow is applied to simulate the FDI (including pre-loading) on the pad scale. The workflow is capable of simulating the entire life cycle of the FDI interaction, (a) stimulation of parent wells, (b) production of parent well, (c) pre-loading of the parent well, (d) stimulation of the child wells, and (e) production forecasting of both parent and child wells. The workflow includes calibration with field observations of fracture geometry, production performance, pre-loading pressure behavior, etc. Geomechanics and reservoir simulation coupling captures the stress change due to the depletion at the parent well and re-pressurizing from pre-loading.
The workflow was applied to one pre-loading pilot test in the Permian Basin. The goal of the study is to identify the key parameters that contribute to the pre-loading success and optimize the pre-loading design. History match of parent and child wells production performance using the integrated and coupled geomechanics / fluid flow / fracturing propagation modeling workflow was conducted to calibrate and validate the model. Then, a sensitivity study was performed on various key parameters, including pre-loading volume and level of depletion at the parent well to understand its impact on the production performance at the parent and child wells. Learnings from this study provided guidance to the operation team in order to optimize FDI mitigation strategy.