Abstract

The collective behavior in seismicity, (Dynamic Parameter Analysis, DPA), provides an approach for examining the deformation and stress behavior as related to the Top-Wait-Down (TWD) completion of two stacked wells within the Midland Basin. Both the influence of pre-stimulation and depletion could be observed in the DPA. Initial deformation in the Lower Spraberry formation, related to the development of a complex fracture network near the wellbore, was further enhanced by the stimulation of the Wolfcamp A well. After the first proppant was introduced an increase in deformation of the pre-stimulated zone was observed, suggesting reactivation of induced fabric occurred. We suggest that stress transfer was related to a stress difference between the two zones and that the Lower Spraberry was in a critical stress state. As a result, reactivation of Lower Spraberry stimulated fabric enhanced production compared to wells that did not utilize TWD. Comparing wells with TWD to those without TWD showed marked uplift in production from the Lower Spraberry Wells, with no detriment to the Wolfcamp A production. We postulate from DPA analysis and supporting data that this uplift was related to slip along pre-stimulated and critically stressed fractures related to stress transfer from trailing Wolfcamp A stages. Based on these observations, we suggest that the observed stress transfer process is a paradigm shift on how completion operations and full-field resource development should be approached in the Permian.