Hydraulic fracture optimization by using a modified Pseudo-3D model in multi-layered reservoirs

摘要

The aim of hydraulic fracturing optimization is to maximize well productivity index by optimizing fracture geometry parameters. Height in geometry calculation is the most important parameter, especially in the multi-layered reservoirs due to the complexity of the in-situ stress distribution. A modified pseudo-3D model suggests a combination of unified fracture design (UFD), 2D fracture propagation models (PKN or KGD) and linear elastic fracture mechanic (LEFM) principle to achieve optimized fracture geometry. First, the LEFM principle has been used to obtain equilibrium fracture height associated with a calculated vertical pressure distribution along the in-situ stress and fracture toughness profiles. Then, the UFD concept in conjunction with 2D fracture models are used to obtain an optimum fracture target length, the corresponding net pressure, and the maximum dimensionless productivity index. This paper shows the insight of the new approach of hydraulic fracture optimization by using an efficient and practical algorithm in calculating equilibrium fracture height growth belong to certain treating pressure. The proposed model is applicable to broad-spectrum of multi-layered oil and gas reservoirs with more accurate estimation of final fracture height and treating pressure. Finally, two case studies have been used to represent that the model is effective and appropriate for practical purposes.