A Permian Basin case study is presented to provide a better mechanistic understanding of parent-child well fracture interference. In the example field scenario presented in this paper, the parent well was produced and refractured before the child well was fractured. The key objective of this study was to explain and remedy the 40% reduction in expected EUR of the child wells compared to the parent wells. Another objective was to understand why sand flowback in the child wells was observed to be 4 times that in the parent wells.

A 3-D reservoir-scale poro-elastic geomechanics software (Multi-Frac-3D) was used to model the depletion of the parent well and calculate the induced stress changes. The impact of induced unpropped (IU) fractures around the parent well on the induced stress changes was analyzed. The production of the parent well was history matched to estimate the stimulated reservoir volume (SRV) and fracture dimensions. The stress changes and stress reorientation induced by reservoir pressure depletion was captured in the simulations. Different mechanisms that could cause child well under-performance were evaluated. Strategies for improving the hydrocarbon production for the parent-child well pairs were suggested. The simulation results were corroborated with field diagnostic data.

The key mechanisms that control the performance of the child well are the extent of the depletion region around the well, poro-elastic stress changes induced by depletion and the stress changes induced by refracturing. The poro-elastic capabilities of Multi-Frac-3D enable the calculation of the reservoir stress changes induced by depletion and re-fracturing (fracture opening or re-opening). These stress changes explain the observed fracture hits from child wells. The lower stresses induced by the depletion are also used to explain the greater proppant flowback in the child well.