Carbonates and Evaporites

, Volume 3, Issue 1, pp 33–52 | Cite as

Reservoir characterization, porosity, and recovery efficiency of deeply-buried paleozoic carbonates: Examples from Oklahoma, Texas and New Mexico

  • Joachim E. Amthor
  • David C. Kopaska-Merkel
  • Gerald M. Friedman
Petrophysics of Carbonate Reservoirs


Capillary-pressure data from the Early Ordovician Ellenburger Dolomite (west Texas and New Mexico) and the Late Ordovician-Early Devonian Hunton Group carbonates (Oklahoma) are used to calculate or infer petrophysical characteristics, such as median pore-throat size, pore-throat size distribution, effective porosity, and recovery efficiency (RE). For both data sets, porosity and RE are inversely related. A positive relationship between RE and porosity has been reported by other workers, but the relative importance of these opposed trends is unknown. The ability to accurately predict which relationship will hold in a given reservoir unit would be of great value for predicting reservoir performance.

RE is also inversely related to median throat size. This is a consequence of two controlling factors: rock characteristics and experimental procedure. Drainage (recovery) from small throats is more efficient than from large throats, and hysteresis limits recovery from large throats because throats filled at very low pressures early in the intrusion process remain filled at comparable pressures upon extrusion. The experimental procedure also suppresses extrusion from large throats because the minimum pressure attained on extrusion is greater than the initial intrusion pressure, due to limitations of the apparatus.

Reservoir rocks are classified in terms of their capillary-pressure curve form, because curve form is controlled by a variety of petrophysical factors which can be measured, and because curve form is strongly correlated with recovery efficiency. Steep-convex capillary-pressure curves correspond to samples with high REs, low porosities, small median throats, and high entry pressures. Steep-concave curves correlate with low REs, high porosities, large median throats, and low entry pressures. Gently-sloping curves correspond to samples with moderate REs, intermediate median throat sizes, poorly-defined entry pressures, platykurtic throat-size distributions, and variable porosities. Polymodal curves result from polymodal throat-size distributions, and exhibit variable REs and porosities.

Steep-concave and steep-convex curves are interpreted in two quite different ways, as follows. Steep-convex curves indicate reservoir rocks with high REs, but low porosities and small throats, so that production is likely to be economical only under high pressures (or thick oil columns) or from very large hydrocarbon pools. Conversely, steep-concave curves indicate porous reservoir rocks with large throats but probably poor primary recovery efficiency. These reservoirs will be economical even at low pressures and with short oil columns and small total reserves, but will probably need enhanced recovery to produce a significant proportion of reserves. This classification may allow characterization of an “ideal” capillary-pressure curve, which is characterized by a moderate entry pressure, intermediate median throat size, good RE, moderate porosity, and leptokurtic throat-size distribution.

Capillary-pressure plots showing both cumulative and incremental mercury intrusion are more useful than the traditional graphs which show only cumulative intrusion. The incremental intrusion histograms used here highlight modal throat sizes (or modal capillary pressures) which are not well-displayed on cumulative plots. The existence of multiple modes is significant because it affects the relationship between Rwa (water saturation) and oil recovery efficiency, as well as overall nonwetting-phase recovery efficiency.


Dolomitization Recovery Efficiency Reservoir Rock Apparent Porosity Entry Pressure 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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  1. AMSDEN, T.A., 1960, Hunton stratigraphy, part 6 of Stratigraphy and Paleontology of the Hunton Group in the Arbuckle Mountains region: Oklahoma Geol. Surv. Bull., v. 84, 311 p.Google Scholar
  2. AMSDEN, T.A., 1975, Hunton Group (Late Ordovician, Silurian, and Early Devonian) in the Anadarko Basin of Oklahoma: Oklahoma Geol. Surv. Bull, v. 121, 214 p.Google Scholar
  3. AMSDEN, T.A., 1980, Hunton Group (Late Ordovician, Silurian, and Early Devonian) in the Arkoma Basin of Oklahoma: Oklahoma Geol. Surv. Bull., v. 129, 136 p.Google Scholar
  4. BARNES, V.E., CLOUD, P.E., JR, DIXON, L.P., FOLK, R.L., JONAS, E.C., PALMER, A.R. & TYNAN, E.J., 1959, Stratigraphy of the pre-Simpson Paleozoic subsurface rocks of Texas and southeast New Mexico. Univ. of Texas, Austin, Bur. Econ. Geology Publ. 5924, 2 vols., 836 pp.Google Scholar
  5. BEARDALL, G.B., Jr., 1983, Depositional environment, diagenesis and dolomitization of the Henryhouse Formation, in the western Anadarko Basin and Northern Shelf, Oklahoma. Unpubl. MS thesis, Oklahoma State University, 127 p.Google Scholar
  6. BOGGS, Sam, Jr., 1987, Principles of Sedimentology and Stratigraphy. Columbus, Merrill Publ. Co., 784 p.Google Scholar
  7. ELIAS, R.J., McAULEM, R.J. & MATTISON, B.W., 1987, Directional orientations of solitary rugose corals: Can. Jour. Earth Sciences, v. 24, p.806–812.CrossRefGoogle Scholar
  8. FRIEDMAN, G.M. and SANDERS, J.E., 1967, Origin and occurrence of dolostones, p. 267–378,in, Chilingar, G.V., Bissel, H.J., and Fairbridge, R.W., eds., Carbonate rocks, origin, occurrence and classification: Amsterdam, Elsevier Publishing Company, 471 p.CrossRefGoogle Scholar
  9. GHOSH, S.K., URSCHEL, S.F., and FRIEDMAN, G.M., 1987, Substitution of simulated wellcuttings for core plugs in the petrophysical analysis of dolostones: Permian San Andres Formation, Texas: Carbonates and Evaporites, v. 2, p. 95–100.Google Scholar
  10. GREGG, J.M. and SIBLEY, D.F., 1984, Epigenetic dolomitization and the origin of xenotopic dolomite texture: Journal of Sedimentary Petrology, v. 54, p. 908–931.Google Scholar
  11. HAM, W.E., 1969, Regional geology of the Arbuckle Mountains, Oklahoma:in, Ham, W.E., ed., Regional geology of the Arbuckle Mountains, Oklahoma: Oklahoma Geol. Surv. Guidebook 17, 316 p.Google Scholar
  12. HAM, W.E., DENNISON, R.H., and MERRITT, C.H., 1964, Basement rocks and structural evolution of southern Oklahoma: Oklahoma Geol. Surv. Bull., no. 95, 302 p.Google Scholar
  13. HARDIE, L.A., 1987, Dolomitization: a critical view of some current views: Journal of Sedimentary Petrology, v. 57, p. 166–183.CrossRefGoogle Scholar
  14. HILLS, J.M., 1984, Sedimentation, tectonism, and hydrocarbon generation in Delaware basin, West Texas and southeastern New Mexico: American Assoc. Petroleum Geologists Bull., v. 68, p. 250–267.Google Scholar
  15. HOFFMAN, P., DEWEY, J.F., and BURKE, K., 1974, Aulacogens and their genetic relation to geosynclines, with a Proterozoic example from Great Slave Lake, Canada:in, Dott, R.H. and Shaver, R.H., eds., Modern and Ancient Geosynclinal Sedimentation: Soc. Econ. Pal. Min. Spec. Pub. 12, p. 38–55.CrossRefGoogle Scholar
  16. JENNINGS, J.B., 1987, Capillary pressure techniques: application to exploration and development geology: American Assoc. Petroleum Geologists Bull., v. 71, p. 1196–1209.Google Scholar
  17. KEITH, B.D. and PITTMAN, E.D., 1983, Bimodal porosity in oolitic reservoir—effect on productivity and log response, Rodessa Limestone (Lower Cretaceous), East Texas Basin: American Assoc. Petroleum Geologists Bull., v. 67, p. 1391–1399.Google Scholar
  18. KOPASKA-MERKEL, D.C., 1987, Microporosity and production potential on ooids: Mesozoic and Paleozoic of Texas: Carbonates and Evaporites, v. 2, p. 125–131.CrossRefGoogle Scholar
  19. KOPASKA-MERKEL, D.C. and AMTHOR, J.E., 1988, Reservoir characterization with very high-pressure porosimetry: Carbonates and Evaporites, v. 3.Google Scholar
  20. KOPASKA-MERKEL, D.C., AMTHOR, J.E., and FRIEDMAN, G.M., 1987, Notes on the use of a mercury porosimeter (Micromeritics Pore Sizer 9305), Northeastern Science Foundation Technical Report No. 1. Troy, Northeastern Science Foundation, 12 p.Google Scholar
  21. KRAUSE, F.F., COLLINS, H.N., NELSON, D.A. MACHEMER, S.D. & FRENCH, P.R., 1987, Multiscale anatomy of a reservoir: Geological characterization of Pembina-Cardium Pool, West-Central Alberta, Canada: American Assoc. Petroleum Geologists Bull., v. 71, p. 1233–1260.Google Scholar
  22. LOUCKS, R.G and ANDERSON, J.H., 1985, Depositional facies, diagenetic terrranes, and porosity development in the Lower Ordovician Ellenburger Dolomite, Puckett Field, Pecos County,, Roehl, P.O. and Choquette, P.W., eds., Carbonate Petroleum Reservoirs. Springer Verlag, New York, p. 21–37.Google Scholar
  23. MACHEL, H.-G. and MOUNTJOY, E.W., 1986, Chemistry and environments of dolomitization: Earth Science Reviews, v.23, p. 175–222.CrossRefGoogle Scholar
  24. MANNI, F.M., 1985, Depositional environment, diagenesis, and unconformity identification of the Chimneyhill subgroup, in the western Anadarko Basin and Northern Shelf, Oklahoma. Unpubl. MS thesis, Oklahoma State University, 129 p.Google Scholar
  25. MATTES, B.W. and MOUNTJOY, E.W., 1980, Burial dolomitization of the Upper Devonian Miette buildup, Jasper National Park, Alberta, p. 259–297,in, Zenger, D.H., Dunham, J.B., and Ethington, R.L., eds., Concepts and models of dolomitization: Society of Economic Paleontologists and Mineralogists, Special Publication 28.Google Scholar
  26. MEDLOCK, P.L., 1984, Depositional environment and diagenetic history of the Frisco and Henryhouse formations in central Oklahoma. Unpubl. MS thesis, Oklahoma State University, 146 p.Google Scholar
  27. MICROMERITICS INSTRUMENT CORP., 1983, Instrument manual, Pore Sizer 9305. 1 Micromeritics Dr., Norcross GA 30093 USA. (404) 662-3666.Google Scholar
  28. PLUIM, S.B., PAINTER, P.G., BUCHER, E.J., and CHAKY, A.L., 1985, Log-analysis problems associated with bimodal pore system, Interlake Formation, North Dakota: American Assoc. Petroleum Geologists Bull, v. 69, p. 296.Google Scholar
  29. PRUATT, M.A., 1975, The southern Oklahoma aulacogen: a geophysical and geological investigation: MS thesis, University of Oklahoma, Norman, 59 p.Google Scholar
  30. STERNBACH, C.A. and FRIEDMAN, G.M., 1986, Dolomites formed under conditions of deep burial: Hunton Group carbonate rocks (Upper Ordovician to Lower Devonian) in the deep Anadarko Basin of Oklahoma and Texas: Carbonates and Evaporites, v. 1, p. 61–73.CrossRefGoogle Scholar
  31. THROCKMORTON, H.C. and AL-SHAIEB, Z., 1986, Core-calibrated logs utilization in recognition of depositional facies and reservoir rocks of the Henryhouse Formation (Silurian), Anadarko Basin: Proceedings, SPLWA 27th Ann. Logging Symp., p. L1–L18.Google Scholar
  32. WARDLAW, N.C., 1976, Pore geometry of carbonate rocks as revealed by pore casts and capillary pressure: American Assoc. Petroleum Geologists Bull., v. 60, p. 245–257.Google Scholar
  33. WARDLAW, N.C., 1980, The effects of pore structure on displacement efficiency in reservoir rocks and in glass micromodels: SPE AIME, Symp. on Enhanced Oil Recovery, Tulsa, Preprint SPE 8843, p. 345–352.Google Scholar
  34. WARDLAW, N.C. and MCKELLAR, M., 1981, Mercury porosimetry and the interpretation of pore geometry in sedimentary rocks and artificial models: Powder Tech., v. 29, p. 127–143.CrossRefGoogle Scholar
  35. WARDLAW, N.C., MCKELLAR, M., and YU, L., 1988, Pore and throat size distribution determined by mercury porosimetry and by direct observation. Carbonates and Evaporites, v. 3.Google Scholar
  36. WARDLAW, N.C. and TAYLOR, R.P., 1976, Mercury capillary pressure curves and the interpretation of pore structure and capillary behaviour in reservoir rocks: Bull. Can. Pet. Geol., v. 24, p. 225–262.Google Scholar
  37. WUELLNER, D.E., LEHTONEN, L.R. and JAMES, W.C., 1986, Sedimentary-tectonic development of the Marathon and Val Verde basins, West Texas, U.S.A.: A Permo-Carboniferous migrating foredeep. Int. Assoc. Sedimentologists Spec. Pub. 8, p. 347–368.Google Scholar
  38. WAY, H.S.K., 1983, Structural study of the Hunton lime of the Wilzetta Field, T12–13N, R5E, Lincoln Co., Oklahoma, pertaining to the exploration for hydrocarbons. Unpubl. MS thesis, Oklahoma State University, 40 p.Google Scholar
  39. YU, LI, LAIDLAW, W.G. and WARDLAW, N.C., 1986, Sensitivity of drainage and imbibition to pore structures as revealed by computer simulation of displacement process: Advances Colloid and Interface Sci., v. 26, p. 1–68.CrossRefGoogle Scholar
  40. YU, LI and WARDLAW, N.C., 1986, The influence of wettability and critical pore-throat size ratio on snap-off: Jour. Colloid Interface Sci., v. 109, p. 461–472.CrossRefGoogle Scholar
  41. YU, LI and WARDLAW, N.C., 1986, Mechanisms of nonwetting phase trapping during imbibition at slow rates: Jour. Colloid Interface Sci., v. 109, p. 473–486.CrossRefGoogle Scholar
  42. ZENGER, D.H., DUNHAM, J.B., and ETHINGTON, R.L., eds., 1980, Concepts and models of dolomitization. Soc. Econ. Pal. Min. Spec. Publ. 28, 320 p.Google Scholar

Copyright information

© Springer 1988

Authors and Affiliations

  • Joachim E. Amthor
    • 1
    • 2
    • 3
  • David C. Kopaska-Merkel
    • 1
    • 2
    • 3
  • Gerald M. Friedman
    • 1
    • 2
    • 3
  1. 1.Graduate School of the City University of New YorkNew York
  2. 2.Department of GeologyBrooklyn CollegeBrooklyn
  3. 3.Northeastern Science Foundation affiliated with Brooklyn CollegeRensselaer Center of Applied GeologyTroy

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