Commonly, bridging materials used to reduce formation damage and mud losses in the near wellbore region consist of solid particles. These particles need to be removed after drilling through processes such as acidizing. Microbubble-based drilling fluids utilize gas bubbles to bridge the pores instead of solid particles. These microbubbles can be removed during the initial stages of production, thereby, reducing the costs associated with stimulation processes. Although there has been some work done on the flow of microbubbles through porous media, little is known regarding what conditions (e.g. viscosity, fluid composition, pressure) determine whether the microbubbles will or will not block the pores. Both the microbubble diameter and the rock pore size distribution play roles in determining sealing of the pores. In order to gain an appreciation of the pore blocking mechanism, experiments were conducted using micro-model cells to visually understand the blocking mechanism. The composition of the fluid is varied, as well as the flow rate at which the El aid is injected. Through this, the pressure at which the microbubbles invade the medium for various compositions of the fluid for pore blocking is determined. The average microbubble size at the invasion pressure is compared to the average pore size of the porous medium. By understanding the extent of the microbubble invasion under varying conditions, a greater comprehension of the pore blocking mechanism can be established. As well, the success rate of applying the microbubble system to various types of reservoirs can be evaluated.