Sediment gravity-flow deposits and three-dimensional stratigraphic architectures of the linked Cutoff, upper Bone Spring, and upper Avalon system, Delaware Basin

摘要

The Bone Spring play and associated Avalon subplay represent a succession of calcareous, siliceous, and carbonaceous sediment gravity-flow deposits associated with significant production of oil, condensate, and dry gas in theDelaware Basin, Texas. Correlation of the upper Bone Spring and upper Avalon systems to the outcroppingCutoff Formation slope systemand lower SanAndres composite sequence (Permian composite sequence 9 [PCS9], 2-4 m.y.) in the Guadalupe Mountains region allows us to investigate how slope and basinal accumulation patterns are linked to deposit types and migration patterns of the active sediment factory (shelf system). The Cutoff-upper Bone Spring-upper Avalon interval in the northern Delaware Basin records the multivariate evolution of a deep-water system associated with a drowned carbonate platform margin (large-scale inflection) characterized by (1) an increase in the rate of sediment supply to the drowned platform, (2) a transition along the relict platform from styles of sediment transport dominated by turbidity currents to styles dominated by mass-transport events, and (3) a landward shift in the locus of deposition downdip of the relict shelf margin. Reservoir-prone strata of PCS9 associated with turbidite systems demonstrate basinward-stepping geometries along shallow slope gradients downdip of the relict shelf margin and aggradational geometries along steep slopes. Nonreservoir strata associated with carbonate-rich mass-transport deposits of PCS9 accumulate near the relict shelf margin on both shallow and steep slopes. Insights developed from this study can help to improve exploration activities in the Delaware Basin and in other basins having analogous deep-water systems.