Designing Matrix Acidizing Treatments with Particulate Diverters—Part I: Model and Predictions

Abstract

While particulates are often used in the field to optimize reservoir coverage by diverting the injected treatment fluids into lower injectivity zones, the optimal job design may be difficult to reach without the proper models. In our study, we detail models for particulates transport, bridging, plugging, diversion and degradation, which are the tools required to provide reservoir and completion specific design guidelines for various scenarios. Each model is built using dedicated experimental procedures. Experimental data are presented together with their correlations. The efficiency of particulate fluids depends on multiple factors including the magnitude of the injectivity contrast present in the reservoir, how much flow resistance may be achieved by accumulating particulate filter cakes in perforations and how quickly the accumulation can start. The onset of diversion requires perforation plugging and, potentially before that, perforation bridging. The onset of bridging depends on parameters such as particulate loading, rate through perforations, and size of perforations and of particulates. Once the cake forms, diversion may start depending on the permeability of the cake, the permeability of the zone connected to the plugged perforation, and the perforation type. Particulate and cake degradation rate is also an important aspect to consider. This paper elaborates on the models relevant to quantify diversion efficiency of particulate-based fluids in the field. The paper also provides new and useful insights on the important factors that should be considered during the design phase.