HPHT challenges Downhole Seal Stacks with softening at 550°F, addressed by FEPM elastomers retaining elasticity. Extrusion gaps widen thermally, countered by PEEK fillers. Greene Tweed's Fusion FKM withstands 450°F and RGD. Finite element models predict 20-year life, vital for ultra-deep GoM wells. https://globalsealstech.com/media/