As unconventional basins mature, infill drilling and completion campaigns take a more central role in field development planning, not only for maximizing infill well potential, but also for protecting the economic potential of pre-existing wells. Reservoir depletion from parent wells can create localized "pressure sinks." When a nearby infill well is fractured, the hydraulic fracture grows towards areas of lowest stress (the depleted area), which can damage the parent well. Subsequently, the production potential of the new well is decreased because it is now draining from the same reservoir area as the parent well. In a damaging fracturing hit from an infill well, the parent well can lose some to all of its production compared to rates before the fracturing hit. Sometimes, simply shutting in the parent well is not sufficient to prevent this damage.
In this paper, more than 3,100 fracture interferences in 5 major basins (Eagle Ford, Bakken, Haynesville, Niobrara, and Woodford) are examined to determine which basins are more prone to positive or negative fracture interferences from new infill wells. The Haynesville and Bakken have more positive fracture hits than the other basins, while a majority of the fracture hits in the Woodford and Niobrara are negative.
With the advent of modern diversion-based refracturing techniques, it is possible to create a "pressure barrier" around the parent well that helps redirect the new fracturing treatment into other, virgin areas of reservoir. By refracturing the parent well first, this may not only preserve the original production of the parent well, but it may also increase the production of the parent well as well as the new infill wells. Although refracturing adds to the capital expenditure of the project, project economics may be more favorable with the investment in parent well refracturing. Examples of parent well refracturing are also presented in this paper.