A review and perspective on far-field hydraulic fracture geometry studies

A review of the published literature and expert opinions shows that the traditional oil and gas industry paradigm for far-field hydraulic fracture geometry - simple, deterministic fracturing - is changing to include the potential for creating complex fracture geometries. For six decades, the established paradigm has purported the creation of two mirror-image fracture wings radiating from opposite sides of the wellbore with each wing growing into the far-field as a single (deterministic) fracture along a single plane. This review found that the roots and development of this paradigm are based in theory and laboratory studies that were pre-disposed to the bi-wing, deterministic geometry. These studies lacked critical factors (e.g., realistic wellbore-casing descriptions; realistic fluid rheologies; simulated pumping histories; including stoppages and slowdowns; formation heterogeneities, etc.), that can foster the creation of complex fracture geometries. In addition to a historical perspective, this review summaries studies from the last decade that were designed specifically to investigate fracture geometry. The data from these studies show multiple, far-field fracture geometries. These data include (1) recovered cores drilled laterally through the fracturing, (2) mining through the fracturing, (3) treatment-induced (i.e., passive) microseismicity, (4) controlled source seismic exploration, (5) borehole overcores and videos, (6) anomalous treatment pressure histories, and (7) surface tilts. The literature from laboratory simulations, theoretical models, and natural hydraulic fracture analogues support these findings, the creation of multiple fracture geometries in the far-field. (C) 1999 Elsevier Science B.V. All rights reserved.