Changes

</ref><ref name=Peppr2020b>Pepper, A. S., E. Rhoden, P. Foy, H. Ross, J. M. Laigle, and C. Yarbrough, 2020b, Petroleum systems modeling of Wolfcamp Formation reservoir fluid saturations and compositions in the Delaware Basin: Key principles and workflows: West Texas Geological Society Annual Fall Symposium, September 23, 2020.</ref>.

</ref><ref name=Peppr2020b>Pepper, A. S., E. Rhoden, P. Foy, H. Ross, J. M. Laigle, and C. Yarbrough, 2020b, Petroleum systems modeling of Wolfcamp Formation reservoir fluid saturations and compositions in the Delaware Basin: Key principles and workflows: West Texas Geological Society Annual Fall Symposium, September 23, 2020.</ref>.

Once the gross shale (Wolfcamp A and B) interval was mapped, the focus shifted to individual horizons within the Wolfcamp A and B. The model was that the basin-floor depositional system contained the organic-rich, silica-rich, very thinly bedded basinal facies with shelf carbonate debris flows into the basin. Very different interpretations of the Wolfcamp were made, depending on what part of the depositional systems within the basin the geologist were most familiar. In outcrop in the Glass Mountains along the southern margin of the West Texas Basin and the Guadalupe Mountains on the basin western margin, the Wolfcamp is dominantly shelf carbonates with minor interbedded siliciclastic shales. The basin center is dominantly the in situ thinly bedded siliciclastic, organic-rich mudstones with the allochthonous shelf carbonate debrites and turbidites. In the Wolfcamp B, the allochthonous carbonates were debrites with coarse shelf clasts in a lime matrix and were easily identifiable in cuttings and imaging logs ([[:file:M125-WestTexas-Figure13.jpg|Figure 13]]). These commonly massively thick (>100’) agglomerated units contained very little organic material. It was interpreted that shelf carbonate gravity flows would continue down the constant angle slope until hitting the basin floor (red line on [[:file:M125-WestTexas-Figure12.jpg|Figure 12B]], [[:file:M125-WestTexas-Figure13.jpg|13B]]), then deaccelerate, depositing the sediment load.

Once the gross shale (Wolfcamp A and B) interval was mapped, the focus shifted to individual horizons within the Wolfcamp A and B. The model was that the basin-floor depositional system contained the organic-rich, silica-rich, very thinly bedded basinal facies with shelf carbonate debris flows into the basin. Very different interpretations of the Wolfcamp were made, depending on what part of the depositional systems within the basin the geologist were most familiar. In outcrop in the Glass Mountains along the southern margin of the West Texas Basin and the Guadalupe Mountains on the basin western margin, the Wolfcamp is dominantly shelf carbonates with minor interbedded siliciclastic shales. The basin center is dominantly the in situ thinly bedded siliciclastic, organic-rich [[mudstones]] with the allochthonous shelf carbonate debrites and turbidites. In the Wolfcamp B, the allochthonous carbonates were debrites with coarse shelf clasts in a lime matrix and were easily identifiable in cuttings and imaging logs ([[:file:M125-WestTexas-Figure13.jpg|Figure 13]]). These commonly massively thick (>100’) agglomerated units contained very little organic material. It was interpreted that shelf carbonate gravity flows would continue down the constant angle slope until hitting the basin floor (red line on [[:file:M125-WestTexas-Figure12.jpg|Figure 12B]], [[:file:M125-WestTexas-Figure13.jpg|13B]]), then deaccelerate, depositing the sediment load.

[[file:M125-WestTexas-Figure13.jpg|center|framed|{{figure number|13}}Thinly bedded, organic-rich, silica facies, and Sheldon Carbonate. (A) Nine (9’) foot vertical image of a Schlumberger FMI (Formation Micro-Imaging Log) in the lower Wolfcamp B. Upper part in the organic-rich, siliceous mudstone. Individual silica-rich beds are millimeters thick. The lower half is the Sheldon Carbonate, a massive (more than 100’ thick) non-bedded, amalgamated debrite. Individual shelf clast can be seen (white and black) floating in the shelf mud matrix. (B) Hanson’s<ref name=Hansn2010 /> isochore map of the Sheldon Carbonate (C.I. = 10’), approximately 54’ gross; 39’ net on the attached Gamma Ray, Neutron–Density Log (dark horizontal lines on the log indicate 10’ vertically; the lighter lines are 2’ vertically on the log). Note the orientation of the debrite oriented subparallel to the slope–basin-floor contact. Other carbonate debrite subfacies isochores have similar subparallel and channel feeder facies perpendicular to the slope, including interpretations mapped by Scott Hamlin<ref name=FairhrstHamln>Fairhurst, B., and S. Hamlin, 2018, Stratigraphic observations of the upper Wolfcampian shale (A&B), Southern Delaware Basin, West Texas: Variations in stratigraphy, depositional processes, mineral facies and log measurements, in W. Fairhurst, ed., Tight Oil Resource Assessment (TORA) Annual Meeting: Bureau of Economic Geology, March 26, p. 91–110.</ref> (reprinted with permission) at the southwest corner of the merging western and southern slope to basin environments just south of this map area.]]

[[file:M125-WestTexas-Figure13.jpg|center|framed|{{figure number|13}}Thinly bedded, organic-rich, silica facies, and Sheldon Carbonate. (A) Nine (9’) foot vertical image of a Schlumberger FMI (Formation Micro-Imaging Log) in the lower Wolfcamp B. Upper part in the organic-rich, siliceous mudstone. Individual silica-rich beds are millimeters thick. The lower half is the Sheldon Carbonate, a massive (more than 100’ thick) non-bedded, amalgamated debrite. Individual shelf clast can be seen (white and black) floating in the shelf mud matrix. (B) Hanson’s<ref name=Hansn2010 /> isochore map of the Sheldon Carbonate (C.I. = 10’), approximately 54’ gross; 39’ net on the attached Gamma Ray, Neutron–Density Log (dark horizontal lines on the log indicate 10’ vertically; the lighter lines are 2’ vertically on the log). Note the orientation of the debrite oriented subparallel to the slope–basin-floor contact. Other carbonate debrite subfacies isochores have similar subparallel and channel feeder facies perpendicular to the slope, including interpretations mapped by Scott Hamlin<ref name=FairhrstHamln>Fairhurst, B., and S. Hamlin, 2018, Stratigraphic observations of the upper Wolfcampian shale (A&B), Southern Delaware Basin, West Texas: Variations in stratigraphy, depositional processes, mineral facies and log measurements, in W. Fairhurst, ed., Tight Oil Resource Assessment (TORA) Annual Meeting: Bureau of Economic Geology, March 26, p. 91–110.</ref> (reprinted with permission) at the southwest corner of the merging western and southern slope to basin environments just south of this map area.]]