An Efficient Model for Hydraulic Fracture Height Growth Considering the Effect of Bedding Layers in Unconventional Shale Formations

Abstract

Summary Understanding and quantifying the effect of the weak bedding layers on the hydraulic fracture height growth in shale formations has always been challenging during the hydraulic fracturing design and operations. This work introduces a comprehensive and nonintrusive hydraulic fracture height growth model that accounts for both formation rock properties and the weak interfaces and can be incorporated into pseudo-3D hydraulic fracture simulators. The formation rock properties are handled by the equilibrium fracture height model. The shear slippage of the weak bedding layers is simulated by an efficient 2D higher-order displacement discontinuity method (HDDM), and the effectiveness on the hydraulic fracture height is quantified by correcting the stress intensity factors (SIFs) at the hydraulic fracture tips. The model is applied in the Permian Basin Wolfcamp formation to quantitatively investigate the effect of bedding layers on the hydraulic fracture height growth. Numerical studies show that the shear slippage of the beddings can significantly slow down the hydraulic fracture height growth and that the shear fracture toughness of the bedding layers and the spacing between the laminations have a considerable impact on the effectiveness of the shear slippage on the fracture height growth. Larger shear fracture toughness and smaller spacing of the bedding layers add more resistance to the fracture height propagation and require larger pressure to breakthrough. Additional results show that the effect of bedding layers is more significant in formations with low-stress contrast but less obvious in formations with high-stress contrast. The impact of the landing depth on the hydraulic fracture height growth is also investigated to provide crucial insights into the optimization of the landing depth in laminated formations.