Evaluation of Established Perforation Cleanup Models on Dynamic Underbalanced Perforating

Abstract

The process of perforating in an underbalanced condition has, for many years, been a widely accepted method for ensuring open, clean, and clear perforation tunnels that are conducive to reservoir flow. With the increased popularity of tubing- conveyed perforating (TCP) during the last several decades, this method and the ability to maximize the amount of pressure differential has become even more popular and is often the preferred completion technique. In the last few years, an enhancement to underbalanced perforating, commonly known as dynamic underbalanced perforating, has been examined both through experiments and models. Dynamic underbalanced perforating is a process that creates a negative pressure differential or underbalance, causing fluid to move toward the wellbore even in an initial overbalanced static condition. A dynamic underbalanced condition can be controlled by understanding and carefully managing the temporal pressure transients, using multiple methods within the wellbore during and after gun system detonation. However, fundamental questions remain: What dynamic underbalanced behavior and pressures are required to remove the perforation-crushed zone, and are existing cleanup models sufficient for predicting perforation cleanup given the reservoir condition? Recently, a series of instrumented perforation experiments using an advanced perforation flow laboratory demonstrated that existing cleanup models do not accurately predict perforation cleanup when perforating in a dynamic underbalanced condition. This work presents initial data and analysis, and suggests a superior method for quantifying perforation cleanup for a given dynamic underbalanced behavior and reservoir condition.