Abstract
The ultra-tight nature of shale reservoirs has resulted in the maximization of the stimulated area within a section to increase production. As a result, some wells appear to interfere with one another during stimulation. This interference has been known to typically reduce (occasionally enhance) the performance of wells currently in production by altering the existing fracture network, or near well permeability, via the presence of multiple phases. This process is known as a "frac hit". Three different mechanisms are thought to be possible causes of the well-to-well interaction: depleted zones, changing stress fields, and high permeability lithofacies. Numerical and analytical modeling will be used to explore the impact of dynamic completion systems.
In this paper, modeling techniques are demonstrated to allow operators the ability to use rate transient analysis (RTA) tools to model frac hits. Examples from the Haynesville and Marcellus are examined. The examples were categorized based on the dominant flow regime, transient linear flow or depletion flow, and then the proper technique was employed. Unique characteristics with respect to reservoir phenomenon, i.e. depleted zone, changing stress fields, or high permeability lithofacies are also discussed.
These modeling procedures will enable operators to bound forecasts for wells that have been altered by the stimulation of a neighboring well. This means operators can still provide risked reserves based on numerical modeling and RTA software for wells that have endured a hit. In addition, the techniques will be applied to re-fracturing. Now operators have the ability to forecast re-fractured wells quantifying the NPV of a re-fracture. Lastly, the knowledge gained from the in-depth examination of the phenomenon and drive mechanisms behind the frac hit enables the avoidance of future occurrences of well damage.
