Using Image Logs to Characterize and Correlate Mass Transport Deposits in the Bone Spring and Wolfcamp Formations, Delaware Basin

The purpose of this work is to show an integrated workflow in which image logs can be used to identify and help define the architecture of deepwater mass transport deposits (MTDs) in the Bone Spring and Wolfcamp Formations in the Delaware Basin. Recognition of MTDs (i.e., debris flows, slumps, slides) has implications for reservoir characterization, formation top selection, mapping, and the understanding of facies architecture. This has significance for drilling and completion of horizontal wells in these unconventional targets, especially when the MTD is subseismic or the seismic is poor. The characterization of MTD features presented involves an integration of more than 10 cores and over 40 image logs. Physical features associated with MTDs on the image log have been calibrated to core using core descriptions, slab photos, and CT imagery. Bedding is characterized from the image logs and separated into the background (normal depositional events) and deformed beds associated with MTDs. Faulting and detachment surfaces are also characterized. Dip patterns identify intervals to further examine for overturned beds, repeated sections, and rafted blocks. These intervals are scrutinized using detailed image logs to verify repeated or overturned facies patterns compared to offset wells or sections of the same well with an undisturbed rock section. Systematic description of deformation features in core can be integrated with image logs to identify regional MTDs in the subsurface. The results will show examples of MTD features that include matrix material, deformed bedding, bed-scale normal- and reverse-slip faults, folded and overturned bedding, and repeated bedding in core and image logs. Typical bed dip patterns observed in MTDs will be shown along with cross sections illustrating how these patterns can aid correlations and mapping. Figure 1 shows a short cross section with an identified MTD that is up to 250 ft thick and spans 16 miles. This study builds upon previous work by providing a core-calibrated framework for systematically characterizing bed dips and patterns in MTDs using image logs. When applied regionally, this work has been important to understanding sediment deposits, explaining regional changes in thickness, and informing depositional models and play concepts. Image logs provide clear-cut evidence of deformation that standard log suites do not resolve. Moreover, this work has been integral to understanding depositional settings in the Delaware Basin, where seismic quality is low in comparison to other fields.