Identify and Mitigate
Parent-child well interactions can lead to compromised frac completions and significantly impact production. While there are several techniques for evaluating pressure communication between active completions and existing wells during or after fracturing treatments (frac hits), greater value comes from the ability to predict and prevent or mitigate these fracture interactions.
D2F is leading the way in predicting frac hits from parent-child interactions The Depleted Fracture Identification (DFI) process identifies where infill wells have crossed existing fractures and, predicts potential frac hits from new completions, and provides actionable recommendations using the same drilling data that creates our OmniLog® lateral profile. The process precisely locates conductive channels between wells through identification of areas of localized depletion. These areas are most often associated with fractures connected to a parent well. The DFI process can therefore be used for frac-hit mitigation, to reduce completion costs, and to understand the fracture growth that occurred in a parent well.
During analysis of Drill2Frac’s OmniLog rock hardness and heterogeneity profiles, Drill2Frac engineers identified changes in RockMSE in infill wells drilled adjacent to existing wells. Further study showed that these unique signatures were likely caused by depleted fractures that were created during the stimulation of the parent well. Drill2Frac then created a methodology to isolate and map these signatures. The resulting fracture maps along the parent and child wellbores allow operators to evaluate different options to control potential fracture interactions. Options include avoiding directly perforating the fractures, using diverters, or changing the pump schedule. In addition, operators have used this knowledge to understand both fracture extension from the parent well and fracture height growth and depletion through stacked reservoirs.
Identification of parent fractures in child wells using the DFI method can give multiple insights to an operator including:
Avoiding fracture hits
Understanding cluster efficiency
Insights into well spacing
Backed by fundamental Engineering principles
Drilling engineers have long known that the differential pressure between the reservoir and drilling mud can significantly affect the ROP and as a result, the mechanical specific energy (MSE) (Vidrine et al SPE 1859). Consequently, it is more difficult to drill through an interval that has been locally depleted due to a parent well fracture. Based on this fundamental principle, the depleted fracture identification (DFI) method uses machine learning along with a proprietary workflow to identify these unique RockMSE signatures that are consistent with these depleted fractures.
The DFI Methodology, was applied in the Point Pleasant (Utica) formation in Ohio. Two child wells were drilled next to a parent well that has been producing for greater than two-years.
While no anomalies were identified in the parent well, multiple were identified in the child wells. Many of these anomalies were consistent across both child wells which is a strong indication that these are indeed fractures from the parent well.
Fractures are qualified using a number of different approaches. For example, the azimuth of the fracture pairs not only is located across from the parent well, but also matches up with the local maximum stress direction.