- In U.S. shale fields, operators are attempting to improve infill well performance. In the Eagle Ford, child wells now account for about 75% of new completions. Infill drilling is ramping up in the Permian, which hosts half of all U.S. drilling.
The transition to infill development in the shale fields has been challenging, and production rates are highly variable and unpredictable. This is due to depletion effects of the parent well that can cause fracture hits and interwell communication among child and parent wells (SPE 174902). In reservoirs with significant depletion caused by parent wells, predicting performance of new infill wells can be difficult. Although operators expect infill wells to perform comparably to, or better than, existing parent wells, the reality is that infill wells often produce below established offset parent well decline curves. This scenario adversely impacts future reserve estimates and, ultimately, field economics.
To increase the understanding of the output relationship between parent and child wells, the service provider studied 3,000 fracture hits across five major unconventional plays, Table 1. The analysis was performed to better understand parent well challenges in each individual field (SPE 180200). The study determined that fracture interference had different effects in different basins, in terms of severity and whether the interference was positive or negative to parents. In most cases, fracture hits on existing parent wells resulted in a positive or no change of trend in the production of the parent well. However, in the Woodford and Niobrara, fracture hits on existing parent wells resulted in a negative or no change trend in the parent well. The Eagle Ford was split, with an approximate 50/50 chance that a fracture hit will be positive or negative to parent well production.
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