Factors affecting the conformity of multi-cluster hydraulic fracture height and length using the plug-perf system - a case study in Kaybob Duvernay source rocks

ABSTRACT: This study provides new insights into the growth of the stimulated rock volume (SRV) during complex multi-cluster hydraulic fracturing, using the plug-and-perf system, in the presence of mechanical anisotropy and heterogeneity in the nano-Darcy permeability Duvernay Formation source rock in the Kaybob region of Alberta. We first consider a case of a Diagnostic Fracture Injection Test (DFIT) in the Duvernay where we quantified the essential SRV properties including SRV compressibility, residual SRV permeability, and the net fracture pressure. Using the analysis, we show that hydraulic fracturing in the nano-Darcy Duvernay source rock will lead to creation of an extensive process zone which will appear to be additional fracture work (higher fracture toughness). In the next step, we demonstrate that number of key frac design parameters, including the optimal landing interval identified using a newly developed failure index and frac pumping rate, can improve the quality of multi-cluster fracture conformity, enhance cluster efficiency, and mitigate out-of-zone frac growth during a multi-cluster plug-and-perf frac job. It is shown that less conformity in the fracture half-length distribution is expected when wells are landed and completed in a less geomechanically competent interval. The conformity will significantly increase when intervals with better fracability are targeted. We will illustrate that targeting these intervals will significantly increase the chance of fracture containment, particularly those installed through inner clusters, while promoting the creation of hybrid fracture geometries including vertical and horizonal fracture components between clusters. It is shown that an increase in the pumping rate can further improve the conformity in the frac half-length distribution. To the end, we will show that the utilization of Extreme Limited Entry (XLE) design will improve the cluster efficiency, while improving the frac conformity and SRV permeability.