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Proposed Stratigraphic Correlation Framework, Wolfcamp, Delaware Basin, West Texas


Wolfcamp of West Texas is labelled “undifferentiated” on Permian Basin stratigraphic columns and industry nomenclature varies. It is here subdivided into five stratigraphic units, using log character, basin-wide correlative marker beds, lithology, and paleontology. Proposed units are based on cross section networks using 5000 raster logs, 900 mud logs, and 62 paleo reports. These units document a sea level highstand, lowstand, and highstand. Haley Unit is a coarsening-upward/fining-upward (CU/FU) sequence of shale and thin bedded carbonate debris 60′ to 2000′ thick, locally erosionally truncated. In SE New Mexico its thin-bedded, high GR shales are indistinguishable from the underlying Penn shales except by paleo data. Significant gas production was found in 1997 in Haley Field, SE Loving County. Debris Unit consists of variable clastic lithologies up to 1900 feet thick. A siliciclastic lowstand fan with sharp basal contact is located in western Delaware basin. In Eddy County, NM, carbonate debris flows have sharp erosional basal contacts. In Winkler and Ward Counties carbonate debris blocks contain reworked Strawn fusulines. In Pecos County, an overturned slide block of Mississippian limestone is documented by well control. Debris Unit is capped by a shale marker and may be time equivalent to Wolfcamp shelf erosional deposits of the Powwow Conglomerate. Red Hills Unit conformably overlies Debris Unit and consists of 1500′ CU/FU thin bedded shale and carbonate debris. Top of unit is a very correlative basin wide shale marker, probably a maximum flooding surface. First significant production was established in 1964 in Red Hills Field, Lea County NM. Ford West Unit conformably overlies Red Hills Unit, and consists of thin bedded CU/FU siliceous shale and carbonate debris beds, 50′ to 1600′ thick. First significant production was discovered in 2011 by Cimarex in the Ford West Field, Culberson County. Phantom Unit (775′ thick) conformably overlies Ford West Unit, and consists of thin bedded, fining-upward, resistive organic rich shales and carbonate debris beds. Three thin siltstone units cap the Phantom Unit. Top of the Phantom Unit (top Wolfcamp) is a mappable shaly marker at base of Leonardian Third Bone Spring Sand. Phantom Unit produces throughout the basin from over 1400 horizontal and vertical wells, including Phantom field (Ward and Loving Counties, discovered 2008), and Wolfbone Trend (Reeves County, discovered 2010).