Abstract

Much potential remains for future academic and applied studies of the Bone Spring Formation in the subsurface of the Delaware Basin. This Leonardian-Guadalupian formation (we correlate the upper part of the Bone Spring in the subsurface with the Cutoff Formation in outcrop) includes the products of deposition on the slope and basin-floor and preserves the record of reciprocal sedimentation. Transgressive and highstand systems tracts consist of carbonates on the slope and in the basin, whereas lowstand systems tracts consist of siliciclastic sediments deposited lower on the slope and out on the basin floor. The original drilling targets (1950s to 1980s) were dolomitized allochthonous carbonate “debris mounds” of the slope. By the 1990s the focus had shifted to the siliciclastic (“sand”) members of the slope and basin. Analysis of the sands, using wireline logs, 3-D seismic data and production data suggests that the location of sediment sources on the shelf and sea-floor relief interacted with relative sea-level changes to control the vertical and lateral distribution of facies. Subtle movements along basement features not only influenced depositional patterns, but also contributed to the development of fracture networks that greatly influence the producing characteristics of the Bone Spring Formation. Future work that examines the genesis of natural fractures in the formation, means of detecting those fractures and the impact of fractures on well performance (e.g., drainage radius) will be needed to better exploit Bone Spring reservoirs.