A numerical study of sequential and simultaneous hydraulic fracturing in single and multi-lateral horizontal wells

Horizontal well hydraulic fracturing (HF) technology can help to develop low permeability oil and gas resources. Today, industry uses simultaneous and sequential fracturing as a means to fracture single or multiple (Zipper Frac) horizontal wells as an efficient way to produce oil/gas. In zipper fracturing two or more parallel wells are fractured simultaneously or sequentially to achieve the maximum stimulated reservoir volume. In order to achieve optimum stimulated rock volumes and fracture networks, one must understand the effect of various rock and fluid properties on stimulation to minimize the risk of unwanted fracture geometries. This paper describes the development and application of a 2D coupled displacement discontinuity numerical model for simulating fracture propagation in simultaneous and sequential hydraulic fracture operations for single and multiple parallel wells. The sequential fracturing model considers two different boundary conditions for the previously created fractures. A constant pressure boundary condition along the fracture surface is considered when the flow back is restricted between the stages and a joint model is used when fractures are propped. A series of examples are presented to study the effect of fracture spacing on expected stimulated zone. It is found that fracture path is not only affected by fracture spacing but also by the boundary conditions on the previously created fractures.