This paper discusses the use of solid-steel expandable refrac liners as mechanical barriers to isolate old perforations in the lateral section of horizontal shale-gas wells with declining production to allow reperforation and fracture stimulation of new shale volume between the old perforation clusters. The technology and installation of expandable solid-steel refrac liners are presented with a summary of other refrac diversion methods. Two case histories demonstrating the application of solid-steel expandable refrac liners to ~3000 ft (914 m) laterals in the Barnett Shale are presented. These case histories document the first successful use of solid-steel expandable liners to achieve frac-stage diversion when refracturing horizontal wells. The challenge was to use a solid-steel expandable 4-1/4 in. (107.95 mm) OD [outside diameter] liner in the 5-1/2 in. (139.7 mm), 17 lb/ft (25.30 kg/m) base casing as a mechanical barrier with elastomer seals on the exterior of the refrac liner placed to achieve both stage isolation and the desired degree of perforation isolation. Once in the setting position, the refrac liner, connections, and elastomer seals were expanded using a cone-driven process from the toe to the heel of the lateral to isolate frac stages and perforation clusters, and to maximize the ID [internal diameter] of the refrac liner. The multi-stage refracturing treatment was performed next after shooting new perforations for each stage through both the expanded liner and the base casing. Offset wells served as benchmarks as they were refractured using other perforation diversion methods. For the first case history, gas production over a 23 month period following the refrac using the refrac liner exceeded that of the two offset wells by more than 161,000 MCF [1000 cubic ft.] (4.56 E06 m3). For the second case history, gas production from the well with the refrac liner exceeded that of its offset well by 92,000 MCF (2.61 E06 m3) over a 20 month period. The primary advantage of using the refrac liner, however, was that it provided a mechanical barrier to ensure injection into the desired interval for each stage of the frac treatment. This can lessen the requirement and cost for real-time fracturing diagnostics such as downhole microseismic, and eliminate interruptions during refracturing to make downhole adjustments to achieve stimulation objectives