In this study, a special focus was dedicated to the effect of elastic anisotropy of shales on the in-situ stress contrast between different layers and its implications on the vertical containment of hydraulic fractures (HF) and how they relate to the widely observed fracture driven interaction (FDI) phenomena and undesirable HF height growth. The reported elastic and mechanical properties of the main members of the Bakken petroleum system in the Williston Basin (i.e. Upper and Lower Bakken Shale, Middle Bakken, and Three Forks) (Ellafi et al., 2019) was used to estimate the in-situ stresses based on anisotropic rock properties and use the minimum horizontal stress profile for HF modeling. The estimated stress profile appeared to be very different from the one calculated based on the isotropic formation assumption. The anisotropic stress model, as reported by other researchers, is more realistic in transversely isotropic rocks and rock with a high volume of clay and TOC and generated more reliable results that conform better with other indicators and observations from other types of data associated with HF geometry.

Multi-stage hydraulic fracturing technology for enhanced production from unconventional reservoirs has improved significantly during the past decade. However, multi-stage fracturing for multiple closely spaced long horizontal wellbores introduces several technical challenges. One example is Fracture Driven Interaction (FDI). In this study, we document a Fracture Driven Interaction case study where the primary well was drilled into the Three Forks Formation, and an offset well was drilled in the Middle Bakken. The idea of this study was to investigate the possibility of frac-hit as the cause of the low production rate in the offset well. This study estimates the stress in the petroleum system, and combine that with petrophysical analysis to construct a fully coupled hydraulic fracturing, geomechanics and reservoir numerical model. The model matched the production data and the results show the occurrence of a fracture driven interaction was a result of stress decrease due to depletion. Fracture driven interaction effect was severe on the offset well reducing the stimulated reservoir volume, thus jeopardizing the production.

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