A Semianalytical Productivity Model for Openhole Perforated Vertical Wells

Summary Openhole perforated completions offer the dual advantage of minimizing formation damage associated with cementing operations and maximizing reservoir exposure, making them particularly promising for enhancing production from low-porosity, low-permeability reservoirs. Such completion practices have been applied in multiple oil fields. Traditional productivity predictions for perforated wells are typically expressed in terms of skin factor and have largely focused on casedhole perforations, with limited models addressing openhole perforated completions. For this study, we developed a semianalytical productivity model in which key empirical parameters are calibrated using high-fidelity numerical simulations that explicitly represent the wellbore, perforations, and reservoir properties. The model incorporates both drilling-induced formation damage and perforation-induced compaction effects. Validation against independent numerical simulations demonstrates good agreement, confirming the reliability of the proposed approach. Further analysis indicates that, for relatively shallow perforation penetration in low-permeability formations, openhole perforations provide a measurable productivity advantage over casedhole perforations; however, this advantage decreases once the perforation depth exceeds a critical depth. The proposed semianalytical framework provides a practical and efficient tool for rapid productivity evaluation and perforation design optimization in vertical openhole wells.