Abstract
In recent years, complex well explorations have moved into more challenging environments (ultra-deep, high-pressure/high-temperature (HPHT), extended reach laterals). These environments require a closely integrated and multidisciplinary process to ensure efficiency and mitigate risk. In particular, the process of perforating has called for careful design, planning and execution to prevent costly failures and maximize productivity over the life of the well. The perforating systems used in these environments can place a large dynamic load on downhole equipment. Predicting the magnitude and transient behavior of such loads is a critical step in developing completion designs that can be executed safely while avoiding damage or destruction to downhole tool strings and production equipment. Further, post-job well production rates often depend strongly on the proper choice of perforating job design parameters relating to formation integrity, tunnel cleanup, underbalance management, subsequent stimulation methods, etc. Predicting the complex interdependencies between these parameters is crucial for a successful job.
The simulation software presented in this work is based on a next-generation, dynamic downhole modeling platform that simulates the dynamic response of a cased or uncased wellbore, its contents, and the porous rock formation to the energy released by gas-generating and stored pressure sources. The software is applied to predict dynamic flow around the wellbore/formation, evaluate cleanup and mitigate gun shock loads. For complex well completions, the software incorporates differentiating algorithms for shock-capturing hydrodynamic solvers, improved thermodynamic closure, fluid dynamics and more importantly, significantly faster turnaround simulation times to enable quick pre-job modeling iterations.
The software is comprehensively validated using a variety of benchmarking examples. The improvements in dynamic predictions as well as computational efficiencies with the next-generation software are clearly demonstrated. Beyond standard benchmark cases, the application of this software is demonstrated using successful design examples from wells in the North Sea, Southeast Asia, etc. The simulations presented here provide insight into the complex fluid dynamics between the formation and wellbore, gun shock loads, and how cleanup is maximized and productivity enhanced by subsequent optimization of wellbore/gun systems. In an environment where downhole measurements or laboratory-based testing is impractical, the dynamic modeling software ensures successful execution through pre-job modeling as well as conducting a comprehensive post-job analysis for future planning.
