Perpustakaan Digital ITB

Multi-stage hydraulic fracturing has been increasingly adopted as an effective stimulation method to improve recovery, especially in horizontal wells, where extended lateral contact enables more effective stimulation across a larger portion of the reservoir. While increasing the number of fracture stages is often assumed to enhance reservoir drainage and improve productivity, it does not always lead to better performance. Under a fixed proppant mass, overstaging can result in shorter fracture lengths, which in turn limits reservoir contact and compromises stimulation effectiveness. This study presents a systematic approach to determine the optimum number of fracture stages (n) by integrating fracture geometry estimation using the Unified Fracture Design (UFD) framework by Guk et al. (2019) with gas productivity modeling based on the analytical flow model of Guo et al. (2009). A case study was conducted on a horizontal well in a tight gas reservoir, with a total available proppant mass of 4,000,000 lb. Key fracture parameters, including half-length, width, spacing, and dimensionless fracture conductivity (CfD), were estimated across various number of fracture stages. To ensure full lateral penetration of each fracture, the design first establishes a condition where the fracture penetration ratio (Ix) equals 1. In this case study, that condition was met at n = 14, which served as the geometric baseline. Two scenarios were then evaluated: Case 1 (n ? 14) and Case 2 (n < 14). The results show that although CfD increases in both cases, the highest gas productivity was observed at n = 14, where minimum fracture width requirements were also met. Compared to a conventional unfractured horizontal well, modeled using Joshi modified model proposed by Guo et al (2007), the optimized design with 14 fracture stages resulted in a 3.21-fold of increase in productivity. These findings highlight the importance of designing fracture geometry under an optimum number of fracture stages with a balanced combination of spacing and conductivity to maximize drainage efficiency, which reflects how effectively the reservoir is accessed and stimulated. Building on this, the proposed methodology offers a reliable and practical framework to support fracture stage optimization under real reservoir and operational constraints. Keywords: multi-stage fracturing, horizontal well, fracture geometry, number of fractures stages