Geomechanical considerations in hydraulic fracturing designs

The role of geomechanics in design and evaluation of hydraulic fracture stimulations in unconventional reservoirs has become more important than ever. Microcosmic mapping provides a good estimation of fracture geometry and stimulated reservoir volume (SRV); however, without geomechanical considerations, the predictions may not be completely accurate. By understanding reservoir rock mechanics and those parameters that have a major impact on the performance of fracture treatments, more reliable decisions in fracturing design and optimization can be made. This paper presents the results of an analytical model that predicts the changes in stress anisotropy in the neighborhood of the fractures of different designs in an elastic-static medium. Also, a numerical model has been developed to investigate the effect of different geomechanical parameters on the geometry of the fractures. Results show that the spacing between fractures has a major impact on the changes in stresses. The effect of well spacing on fracture geometry in modified zipper frac design has been investigated. The results of this study give valuable insight into optimization of fracture placement in newly developed designs of hydraulic fractures in horizontal wellbores.