Openhole gravel packing for sand control offers productivity and cost advantages to cased-hole completions in thick, high-permeability sands. Filter cake, formed by the reservoir drilling fluid, can be trapped by the gravel and cause high drawdown, nonuniform inflow profiles, and low productivity. Effective cleanup and flowback of this filter cake is necessary to fully realize productivity advantages of openhole completions. A comprehensive series of more than 20 laboratory experiments was performed to understand filter-cake flowback in sand-control completions. Variables investigated included mud weight and type, gravel size, additives like enzymes and acids, gravel size, and screen type. The full-length paper summarizes results from 12 of these experiments.