Development of Hydraulic Fractures and Conductivity near a Wellbore

Abstract

Hydraulic fractures play an important role in establishing a high conductive pathway connecting the wellbore and reservoir. The near-wellbore fracture development is crucial to the efficiency of a fracture treatment as a smooth fracture path will reduce the flow impedance. A numerical model is used to simulate the propagation pathways followed by hydraulic fractures, in the presence of a pressurised well and natural fractures. By including the coupling of viscous fluid flow and rock deformation in the analysis, we find that the non-uniform pressure distribution along the fractures and the removal of near-well fracture closure result in growth of a fracture with less curvature (a measure of tortuosity) in its path. Moreover, the fracture curvature can be characterised by two dimensionless parameters. If multiple fractures coexist, fracture linkage is possible due to mechanical interaction between fractures, pre-existing natural fractures and the wellbore. Natural fractures can alter the hydraulic fracture propagation direction, can offset the fracture path and can provide sites for new fracture growth. In the case of two hydraulic fractures initially growing in opposite directions from the wellbore, the interaction with a natural fracture on one side of the well will result in the other fracture wing propagating faster. The complexity of the near-wellbore fracture geometry can be studied with the aid of our numerical model.