The production from a hydraulically fractured unconventional well depends on the stimulated permeability and its interaction with the naturally fractured background permeability. Since the propagation of a hydraulic fracture is often asymmetric and depends on geomechanical factors, the ensuing pressure depletion and the EUR depends on this asymmetric behavior. An analytical asymmetric tri-linear model to approximate pressure depletion is presented. The model uses asymmetric frac design results as input and estimates the pressure depletion around a parent well. This new approach represents an acceptable alternative to full reservoir simulation when investigating frac hits problems.
This asymmetric tri-linear model was combined with our poro-elastic geomechanical modeling simulator in order to capture the physics created by the depleted pressure sink zone. This physics combines the stimulation operations in the neighboring infill well and their interactions with the complex local and far scale geologic features such as natural fractures and faults.
The pressure depletion determined at an Eagle Ford well using the asymmetric tri-linear model was similar to those found with a full reservoir simulator. Hydraulic fracture modeling of a child well located in the vicinity of a parent well with a pressure depleted zone highlighted the potential of developing a frac hit if geological features in the area were creating fluid and pressure conduits. A similar observation is made for a Wolfcamp well where a fault affected the nearby stage causing interference between potential stacked wells.
The integration of the asymmetric tri-linear model and our geomechanical simulator presents the necessary completion modeling tool to quickly, yet accurately design hydraulic fracturing while preventing frac hits, especially now with the increasing of number of infill unconventional wells.