Successful completion of an open hole gravel pack well requires a deposition of a low-permeable filter cake on the wellbore to seal and protect the permeable reservoir formation during drilling and completion operations. The deposited filter cake is removed with the aid of a breaker system before the well is put on production. The placement of a breaker post gravel packing operation brings up a concern regarding the efficiency of the breaker system due to possibly limited contact with filter cake.This study was initiated to simulate the ability of a filter cake breaker system to diffuse through gravel pack carrier fluids inside a screen base pipe and gravel pack. A new apparatus simulating the diffusion and testing protocol were created and used to perform this study. During the experiments breaker system migrated/diffused through a simulated base pipe and packed proppant filled with 10.3 ppg CaCl 2 in less than 24 hours. This proves the ability of a breaker system to contact filter cake in post spot situations. This paper describes a new method built to perform simulations with the objective to calculate the diffusion time and to document the ability of the filter cake breaker to migrate and/or diffuse through a gravel pack at ambient conditions. The paper also establishes the best practices in the design of an effective filter cake breaker system and pumping operations based on the breaker diffusion/migration mechanism.