A completion string includes at least one isolation packer positioned between well zones of a plurality of well zones, and a sand control assembly and a circulating assembly each disposed uphole of a washdown shoe in the bottom-most well zone. A top well zone includes a return valve assembly, a production packer, and a second circulating assembly and a second sand control assembly downhole of the production packer. The completion string also includes an outer string spanning from the bottom-most well zone to the top well zone, and an inner production string concentrically arranged within the outer string, creating an inner-annulus between the outer string and inner production string. The inner-annulus is continuous from the washdown shoe to the return valve assembly, and the inner production string includes a production valve disposed between the sand control assembly and the circulating assembly in each of the bottom-most and top well zones.