his blog post summarizes the model for calculating proppant distribution between perforation clusters. A very detailed description of the model and literature review are available in . The purpose here is to outline the model and its main features, to demonstrate the comparison with some of the available data (more comparisons in ), as well as to discuss limiting cases and sensitivities to various parameters. This blog post is solely focused on presenting the mathematical model. In future work, the results will be applied to practical optimization decisions.