Modelling of Propped Fracture Length for Variable Perforation Shot Designs in Unconventional Wells Undergoing Multi-Stage Hydraulic Fracturing

Abstract The scope of this paper is to model the fracture geometry generated from different perforation shot designs in an unconventional well stimulated with multi-stage hydraulic fracturing. The objective of the paper was to assess the uniformity and symmetry of propped fracture half-lengths conducted through a sensitivity study on the number and distribution of perforating shot designs across a single hydraulic fracturing stage. A 3D transverse fracture simulation model was built using the petrophysical and geo-mechanical properties of an unconventional well, utilizing a commercial fracture simulation software. The objective was to identify the most optimum perforation design yielding the highest stimulation efficiency and fracture uniformity. Five different scenarios were tested: three scenarios with a uniform distribution of perforation holes per stage, and two scenarios with variable perforation distributions. The variable scenarios modeled higher distribution at the toe and heel sides of the stage for two scenarios, and consistent distribution with different number of perforations for three other scenarios. To guarantee a fair comparison between all scenarios, each was simulated with five clusters per stage. All five scenarios exhibited different distribution of fracture half lengths as expected. For the three scenarios with a uniform distribution of perforations per cluster, the lower the number of perforated holes per cluster, the more uniform the propped fracture half lengths were, indicating a clear correlation between fractures uniformity and the number of perforation holes. In contrast, for the two scenarios with variable perforation hole distributions, the one with higher perforation holes closer to the toe of the stage yielded a more uniform fracture geometry compared to the other scenario where perforation holes were concentrated more at the heel of the stage. The scenario with the lowest number of holes distributed uniformly yielded the most uniform distribution of fracture geometry out of the five scenarios. Consequently, the approach and outcomes of this paper are aimed towards the selection of optimum perforation designs, that yield similar fracture geometry symmetry, and ultimately have a positive impact on well deliverability.