An optimal fracture geometry design method of fractured horizontal wells in heterogeneous tight gas reservoirs

Abstract

In this work, the unified fracture design (UFD) is extended for the first time to the fractured horizontal wells in heterogeneous closed box-shaped tight gas reservoirs. Utilizing the direct boundary element method and influence function, the dimensionless fracture productivity index is obtained and expressed in the function of proppant volume and fracture geometry at the pseudo- steady state. With the iterative method, the effectively propped permeability, k fe, is corrected using the in-situ Reynolds number, N Re. The goal of this paper is to present a new UFD extension to design the proppant volume and the optimal fracture geometry. The results show that there exists an optimal proppant volume for a certain reservoir. The small aspect ratio (y e/x e) and high permeability reservoirs need short and wide fractures to diminish the non-Darcy effect. On the contrary, long and narrow fractures are required for the large aspect ratio and low permeability reservoirs. A small proppant volume is prone to creating long fractures, while a relatively large proppant volume creates wide fractures. The new extension can be used to evaluate the previous fracture parameters and design the following fracture parameters of the fractured horizontal well in heterogeneous tight gas reservoirs, with the non-Darcy effect taken into account.