Characterization of Deep-Water Carbonate Turbidites and Mass-Transport Deposits Utilizing High-Resolution Electrical Borehole Image Logs: Late Leonardian (E. Permian) Upper Bone Spring Limestone, Delaware Basin, Southeast New Mexico and West Texas
Jason Asmus and Michael Grammer
Deep-water carbonates of the Upper Bone Spring Limestone are comprised of cyclically-stacked, sub-meter scale turbidites and mass-transport deposits (MTDs) separated by pelagic and hemipelagic siltstone and mudstone. Previous investigations utilized conventional wire-line log and seismic data sets to characterize these deposits, however, the limited resolution of these data sets prevent accurate characterization of the sub-reservoir scale architectural and compositional variations exhibited by these deposits. This investigation integrates high-resolution borehole image logs with conventional subsurface data sets (core and logs) as a means to 1) enhance recognition and evaluate stratigraphic cyclicity of turbidites and MTDs, and 2) provide detailed analysis of architectural attributes associated with turbidite and MTD facies. Results indicate that: 1) >50 % of strata from two cored wells are dominated by turbidity current and MTD deposits, 2) a synthesis of MTD classification schemes allowed for subdividing the MTDs into four categories based on compositional and architectural attributes, 3) >90 % of turbidites and MTDs observed in core are easily identified in image logs, 4) all observed turbidites and MTDs exhibit high-moderate resistivity and are easily discerned from highly conductive pelagic and hemipelagic mudstones, and 5) decreasing gamma ray and increasing resistivity responses from conventional logs are correlative to turbidites and MTDs observed in whole core and electrical image logs. These results suggest integrating electrical image logs with conventional data may significantly enhance recognition and characterization of sub-reservoir scale strata in wells without core data, and aid in the identification and analysis of thinly bedded turbidite and MTD reservoirs.
AAPG Search and Discovery Article #90167©2013 GCAGS and GCSSEPM 63rd Annual Convention, New Orleans, Louisiana, October 6-8, 2013