Evaluation of stress changes due to multi-stage hydraulic fracturing - Consideration of field results

In horizontal well completions for unconventional reservoirs, multiple hydraulic fracturing stages, each often with multiple clusters, are used to provide sufficient stimulated area to make an economic well. Each created hydraulic fracture alters the stress field around it. When hydraulic fractures are placed close enough together, the well-known stress shadow effect occurs in which subsequent fractures are affected by the stress field from the previous fractures. The effects include higher net pressures, smaller fracture widths and changes in the associated 'complexity' of the stimulation. In this paper, we present the results of a numerical evaluation of the effect of multiple hydraulic fractures on stress shadowing for a horizontal well in North America and attempt to highlight the potential cause of the deviation between numerical predictions and field results. The study provides insight into understanding stress shadow effects under field conditions as well as the potential impact on hydraulic fracture stimulations. In addition, the results may help explain the relationship between stress shadowing and microseismic behavior seen in multi-stage horizontals.