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Bone Spring Formation High Resolution Sequence Stratigraphy, Northern Delaware Basin, Eddy and Lea Counties, New Mexico


High resolution sequence stratigraphic analysis of 451 well gamma ray logs coupled to X-ray fluorescence (XRF) and spectral gamma ray logging of five cores of the Bone Spring Formation of the Northern Delaware Basin reveal bicyclic responses between slope to basin sediment gravity flow and pelagic deposition processes which reflect a reciprocal sedimentation model with bathymetric compensational stacking patterns. The eight formation members correspond to third order parasequence sets (PSS), correlate to the third order cycles of the global sea level curve and thus reveal the global eustatic influence to be an important control upon changes in basin accommodation recorded by sediment deposition. Sediment inorganic and organic provenance together with the syndepositional paleoxidation state of the waters are provided by compositional and paleo-envioronmental XRF proxies. The Cr, Co, and Ni proxies suggest transported organic matter during lowstands while the U proxy enrichment implies an in situ pelagic organic matter source during highstands. Together with others these proxies clearly associate siliciclastic terrigenous, detrital influx with lowstands in sea level and highstands with carbonate-rich intervals. In addition, anoxic proxies such as Mn and Fe suggest that though anoxic conditions generally increase with increasing paleobathymetric depth seaward from the shelf, they also alternate with cyclical changes in water depths. During highstands, the anoxic zone was likely vertically restricted but during lowstands it expanded with inferred enhanced Delaware Basin restriction owing to possible curtailment to closure of the Hovie Channel to the Panthalassia Ocean. This high resolution sequence stratigraphic analysis begins to unveil the complicated sedimentary and chemical process-responses of the Delaware Basin during an important time in the Permian, as well as provide practical insight into optimization of Bone Spring oil and gas exploration. Coupling paleoenvironmental proxies with compositional proxies reveal internal heterogeneities within the individual Bone Spring members and make the case for spatially varying source rock, reservoir rock, and potentially self-sourced reservoir quality. Oil and gas exploration and production can use these geochemical indicators to reduce risk in optimized horizontal well placement and to minimize completion costs.