Advanced Analysis of Clean-Up and Productivity from Perforated Rocks Using Computational Fluid Dynamics

Abstract Perforated completions play a crucial role in efficient hydrocarbon recovery as well as long-term well productivity. However, perforating often alters formation permeability around the perforation tunnel, which along with other perforation parameters (penetration, hole size, and shot configuration) significantly impacts near-wellbore pressure drop, and therefore, production. Standard numerical or inflow production models are based on many assumptions involving tunnel geometry and clean-up, debris and damage characteristics. Such an approach often leads to discrepancies between estimated and actual productivity of the tunnel, thereby affecting the overall completion planning through the life-of-the-well. In recent years, perforation flow laboratories have been leveraged to provide insight into clean-up and productivity mechanisms around perforation tunnels. However, the heterogeneity of the analog cores, challenges with isolating competing effects of debris/clean-up and limited amount of experimental data have led to the advent of computational methods. In contrast to previous studies, the model presented in this work leverages the perforation flow laboratory, micro-CT and conventional CT imaging, and most importantly, an advanced simulation approach to provide an accurate assessment of clean-up techniques and productivity. This full-scale three-dimensional flow model accounts for realistic aspects of tunnel geometry, perforation damage, and blockages/debris that impede the flow. The simulation based approach facilitated a comprehensive understanding of the competing effects of perforation damage, debris within the tunnel, tunnel tip plugging, and directionality of flow around the tunnel. Whole-field flow visualization including fluid velocities, streamlines, pressure gradients, and most importantly, the flow rates and corresponding productivity ratio are presented and discussed in detail. Further, this study provided insight into quantitative comparisons of influence of debris and the overall effect of underbalance methods on clean-up and productivity. This work therefore enables the implementation of a multi-scale simulation approach as a practical engineering tool that can be used to provide a realistic prediction of downhole productivity as well as evaluating the effects of clean-up techniques. Such insight will eventually provide information that enhances the decision making process of a perforated completion design.