Outcrop permeabilities within four facies of a single depositional parasequence, upper San Andres Formation (Permian, Guadalupian/Leonardian), Lawyer Canyon, Guadalupe Mountains, Otero County, New Mexico
Malcolm A. Ferris, Charles Kerans, and Sharp, John M., Jr.
Permeability was measured on the upper San Andres Formation (Guadalupian/ Leonardian) outcrop in the Lawyer Canyon area of the Algerita Escarpment, Guadalupe Mountains, Otero County, New Mexico. The study area is a 2613-ft horizontal and 15- to 25-ft vertical section consisting of a single mudstone-bounded carbonate parasequence within the transgressive shelf margin. Four genetic facies were identified within the parasequence: (1) a mud-dominated deep-water flooded shelf; (2) a coarsening-upward, mud-supported ooid and peloid wackestone/packstone shallow shelf; (3) an ooid and peloid, grain-supported bar crest; and (4) an ooid and peloid, grain-supported, coarsening-upward bar flank. Data were collected in the field, with a minipermeameter and in the laboratory, on core plugs from the outcrop. Sampling was performed at 769 locations along 31 vertical transects and in two small-scale orthogonal grid patterns. Separation distances varied from 325 feet between the widest space vertical transects, down to a I-in. separation within the smallest scale grid. Experimental variograms computed for the facies data exhibited a proportionately high nugget-to-sill ratio of poorly developed spherical models. Interpretation of correlation range values in vertical variograms indicate a development of vertical variability within the parasequence, from 13 ft to 2 in. Horizontal variogram analysis for correlation range values indicate a scale dependency based on the sample separation and related variogram lag (h). Horizontal variogram ranges are 253 ft and 748 ft for a lag, h, of 100 ft, 22 ft for h of 10 ft, 4 ft for h of 1 ft and 8 in. for h of I in. An intrinsic test for a power-law function showed that the permeability data exhibit a random or "white noise" relationship for different horizontal variogram search distances. A fractal codimension of 0.07 was calculated, which is an order of magnitude below expectations established for other natural phenomena.
- Ferris, Malcolm A.; Kerans, Charles; Sharp, John M., Jr., 1993, Outcrop permeabilities within four facies of a single depositional parasequence, upper San Andres Formation (Permian, Guadalupian/Leonardian), Lawyer Canyon, Guadalupe Mountains, Otero County, New Mexico, in: Carlsbad Region, New Mexico and West Texas, Love, David W.; Hawley, John W.; Kues, Barry S.; Adams, Jim W.; Austin, George S.; Barker, James M., New Mexico Geological Society, Guidebook, 44th Field Conference, pp. 205-210.