An ongoing challenge in unconventional reservoirs is the significant production degradation (loss of production) realized from child wells drilled adjacent to depleted parent wells. One strategy hypothesized to reduce the realized degradation is to modify the completion design in the child well. The main objective of this case study will be to test this hypothesis and quantify the impact completion design has on child well degradation; specifically, the case focuses on the stage architecture component of completion design defined as the combination of cluster spacing, number of clusters per stage, and stage length. This paper covers an integrated, multi-disciplined review of a unique development situation in the Permian where three different depletion scenarios surround a single well at various well spacings. This data rich review will characterize the SRV (Stimulated Rock Volume) and DRV (Drained Rock Volume) from each of four completion designs within the different depletion scenarios. Data sets include fiberoptic DAS/DTS (Distributed Acoustic/Temperature Sensing) and microseismic during stimulation, along with downhole pressure gauges, chemical tracers, downhole camera for perforation erosion, additional fiber-optic DAS/DTS production logs, and interference (well communication) tests.
A single well with four different completion designs surrounded by three different depletion scenarios creates a rare opportunity to analyze the impact completion design has on child well degradation. Eight different forms of data acquisition technologies were used to increase understanding of completion variable impacts to SRV and DRV as well as validate several new cost-effective data acquisition technologies that were successfully trialed for this pilot. The SRV-related data shows fracture interference with offset depletion, but the amount of interference did not conclusively change among the various completion designs tested. Similarly, DRV-related data shows child well degradation when exposed to parent well depletion, but the amount of degradation did not conclusively change among the various completion designs tested. This suggests that factors other than stage architecture are the dominant drivers of well performance. Detailed analysis from the cross-functional team provides multiple perspectives on the results acquired as they pertain to the overall motivating objectives of the pilot.
