This paper describes a novel process that uses standard drilling data obtained during the drilling of an infill well to identify induced hydraulic fractures that were created during the stimulation of a legacy well. Five case studies are presented to illustrate some insights gained through the application of this process.
This method of detecting fractures involves analyzing the amount of energy expended during the drilling of an infill well. Localized depletion around induced fractures created during stimulation of a legacy well and subsequent production can result in an increased differential pressure between the wellbore and the formation while drilling. This increased differential results in more energy being required to drill through the localized depletion caused by the fracture, allowing these fractures to be precisely located. Mapping these fractures allows operators to gain significant insight in to fracture growth and depletion patterns. In addition, by avoiding these areas of localized depletion during completion, negative fracture interactions can potentially be significantly mitigated or even avoided.
The 5 case studies presented show how this technique has been utilized to understand drainage patterns in stacked plays and how it can be used to understand the extent of dominant fractures being created as well as the horizontal stress orientation as indicated by the fracture direction. The method being deployed in this paper was developed, in February of 2019. This paper is the first to describe how this technique has been used in multiple applications, across multiple basins and reservoirs, to gain insight in to fracture growth and reservoir development as well as to mitigate fracture interactions which have been plaguing the industry.
As more unconventional resource development programs move to an infill drilling phase, understanding the interactions between primary/legacy (parent) and infill (child) wells is becoming more and more important. In some cases, these interactions are positive with no long-term damage to the parent well and can sometimes even increase the production. In many cases though, these "frac-hits" can be quite damaging to the parent wells with loss of production, increased water cut, sand fill, casing collapse or loss of the parent well. Loss of treatment fluid and proppant to the parent well can also mean that the child well is less effectively stimulated resulting in a reduction of potential production from the child well and lower ROI on the infill drilling program. It is because of these risks that many operators seek to minimize primary & infill well interactions.