We use 3D seismic data from an unnamed oilfield to characterize the internal architecture, structure, and porosity and permeability distributions in ultra-deep (> 6 km) Cambro-Ordovician carbonate reservoir strata deposited on a long-lived, regionally extensive carbonate platform in the Tarim Basin, northwest China. These strata comprise three dominant seismic facies: (1) tabular, layered units of sub-parallel to parallel, continuous reflections of medium-to-high amplitude (SPMAC facies); (2) mounds and lenses of chaotic to sub-parallel reflections of low-to-medium amplitude (CPLAD facies), which are widespread in certain stratigraphic levels; and (3) tabular, layered units of parallel, highly continuous reflections of very high amplitude (PVHAC facies). SPMAC facies represents low-energy lagoonal mudstones and wackestones, CPLAD facies represents bioclastic packstones, grainstones, and boundstones in reef-shoal complexes, and PVHAC facies represents alternating gypsum, dolomite, and wackestone-packstone lithologies in the lower part of the reservoir, and the top-reservoir contact between siliciclastic mudstones and packstone-grainstones. Seismic dip-magnitude and time-thickness maps show that CPLAD facies mounds and lenses are present in the middle-to-uppermost reservoir strata, and are associated with folded intervening and overlying SPMAC and PVHAC facies strata. Differential compaction folded these strata. A fourth, minor seismic facies, BPHAD facies, is recognized by parallel, laterally discontinuous, high-amplitude reflections that are stacked vertically and define rugby-ball-shaped beads, strings of beads, and sub-vertical cylinders. BPHAD facies is present in two settings. First, as multiple beads scattered within SPMAC and CPLAD facies strata. Here, we interpret them to represent widespread, small-scale reef-shoal complexes (< 500 m across) or collapsed karst caves. Second, BPHAD facies is present as strings of beads and sub-vertical cylinders near bends in strike-slip faults. We interpret these strings of beads and sub-vertical cylinders to be hypogene karst formed by hydrothermal fluids. This study predicts reservoir permeability and porosity with improved understanding of stratigraphic architecture in the Tarim Basin.