Effects of different stress regimes on hydraulic fracture geometry: a particle flow code approach

Abstract

Hydraulic fracturing decisions are closely tied to quantitative description of rock mechanical properties and in situ stresses in the subsurface. Geomechanics plays a critical role in successfully optimizing hydraulic fracturing, especially in different stress regimes. For those stress regimes that are not normal, the hydraulic fracture geometry is usually more complex and more difficult to predict and investigate. In this study, a particle flow code (PFC) has been developed to investigate and compare the hydraulic fracture geometry in different stress regimes. The results have demonstrated that hydraulic fracture geometry is closely tied to in situ stress conditions, whereas any change in a predominant stress regime from normal to reverse affects the hydraulic fracture geometry. Based on the developed PFC3D model, in a given fracturing pressure, the width and height of the induced hydraulic fracture in a normal stress regime is higher than a reverse stress regime, while the length of the hydraulic fracture in a reverse stress regime is greater than the normal stress regime. The results from this study can be applied in both planning and real-time decisions during hydraulic fracturing jobs to optimize the operation and prevent any job failure which will in turn affect the ultimate productivity.