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An Experimental Study of the Effects of Diagenetic Clay Minerals on Reservoir Sands

Published online by Cambridge University Press:  28 February 2024

Paul H. Nadeau
Paul H. Nadeau*
Affiliation:
Exxon Production Research Company, P.O. Box 2189, Houston, Texas 77252-2189
*
†Present Address: Statoil, N-4035 Stavanger, Norway.
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Abstract

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Despite substantial scientific research efforts, accurate determination of the petrophysical effects of clay minerals on reservoir sands remains problematic. Diagenetic clays such as smectite and illite are of particular interest because of the pronounced effects these clays can have on reservoir quality. Here, results are reported from an experimental study based on the hydrothermal growth of smectite in synthetic sands. The sands contained quartz, dolomite and kaolinite, and were reacted at 175–200°C, for 19–45 d. The hydrothermal reaction can be written as follows:

$$dolomite + kaolinite + quartz \to smectite + calcite + CO<Subscript>2</Subscript>$$
X-ray diffraction (XRD), electron microprobe (EMP) and electron diffraction (ED) analysis show that the synthetic Mg-rich smectite formed is saponite, with a cation exchange capacity (CEC) of about 100 meq/100 g. After reaction, brine permeability reductions of up to 98% were observed from the growth of less than 5% smectite. Scanning electron microscopy (SEM) observations of critical-point-dried reacted samples show that the clay behaves as a pervasive microporous cement with a complex pore-bridging texture affecting most of the available pore space. Morphologically, the clay is similar to naturally occurring diagenetic smectite from Gulf Coast sandstone reservoirs. The delicate clay texture collapses during air-drying and forms pore-lining masses. This phenomenon is similar to that observed for air-dried reservoir samples which contain dispersed diagenetic clays. An air-dried sample, then resaturated with brine, showed a marked increase in permeability. This increase is associated with the irreversible collapse of the clay texture. The experimental results indicate that the growth of diagenetic clay can severely reduce formation permeability, even at very low clay contents. The results also demonstrate the utility of hydrothermal experimental petrophysics for investigating the effects of diagenesis on rock properties.

Keywords

Diagenetic ClayExperimental PetrophysicsPermeabilityReservoir Quality
Type
Research Article
Information
Clays and Clay Minerals , Volume 46 , Issue 1 , February 1998 , pp. 18 - 26
Copyright
Copyright © 1998, The Clay Minerals Society

References

Bain, D.C. Smith, B.S. and Wilson, M.J., 1987 Chemical analysis A handbook of determinative methods in clay mineralogy London Blackie 248–274.Google Scholar
Beard, D.C. and Weyl, P.K., 1973 Influence of texture on porosity and permeability of unconsolidated sand Am Assoc Petrol Geol Bull 57 349–369.Google Scholar
Bjørkum, P.A. and Gjelsvik, N., 1988 An isochemical model for the formation of authigenic kaolinite, K-feldspar, and illite in sediments J Sed Petrol 58 506–511.Google Scholar
Bjørkum, P.A. and Nadeau, P.H., 1996 A kinetically controlled fluid pressure and migration model Am Assoc Petrol Geol Ann Conv Proc Abstr. A15.Google Scholar
Bjørlykke, K., Parker, A. and Sellwood, W., 1983 Diagenetic reactions in sandstones Sediment diagenesis Dordrecht Reidel 169–213 10.1007/978-94-009-7259-9_3.CrossRefGoogle Scholar
Burst, J.F., 1969 Diagenesis of Gulf Coast clayey sediments and its possible relation to petroleum migration Am Assoc Petrol Geol Bull 53 73–93.Google Scholar
Bushell, T.P., 1986 Reservoir geology of the Morecambe Field Habitat of Paleozoic gas in N. W. Europe. Geol Soc Spec Publ 23 189–208 10.1144/GSL.SP.1986.023.01.12.CrossRefGoogle Scholar
deWaal, J.A. Bil, K.J. Kantorowicz, J.D. and Dicker, A.I.M., 1988 Petrophysical core analysis of sandstones containing delicate illite The Log Analyst 29 317–331.Google Scholar
Ehrenberg, S.N., 1993 Preservation of anomalously high porosity in deeply buried sandstones by grain-coating chlorite: Examples from the Norwegian Continental Shelf Am Assoc Petrol Geol Bull 77 1260–1286.Google Scholar
Ehrenberg, S.N. and Nadeau, P.H., 1989 Formation of diagenetic illite in sandstones of the Gam Formation, Haltenbabken area, Mid-Norwegian Continental Shelf Clay Miner 24 233–253 10.1180/claymin.1989.024.2.09.CrossRefGoogle Scholar
Ellis, D.V., 1987 Well logging for earth scientists New York Elsevier.Google Scholar
Harrison, W.J. and Summa, L.L., 1991 Paleohydrology of the Gulf of Mexico Basin Am J Sci 291 109–176 10.2475/ajs.291.2.109.CrossRefGoogle Scholar
Heaviside, J. Langley, G.O. and Pallatt, N., 1983 Permeability characteristics of Magnus reservoir rock 1–29.Google Scholar
Hermanrud, C., Doré, A.G. Auguston, J.H. Hermanrudd, C. Stewart, D.J. and Sylta, O., 1993 Basin modelling techniques—An overview Basin modelling advances and applications. Norwegian Petroleum Soc Spec Publ 3 Amsterdam Elsevier 1–34.Google Scholar
Hurst, A. and Irwin, H., 1982 Geological modeling of clay diagenesis in sandstones Clay Miner 17 5–22 10.1180/claymin.1982.017.1.03.CrossRefGoogle Scholar
Hurst, A. and Nadeau, P.H., 1995 Clay microporosity in reservoir sandstones: An application of quantitative electron microscopy in petrophysical evaluation Am Assoc Petrol Geol Bull 79 563–573.Google Scholar
Hutcheon, I., McDonald, D.A. and Surdam, R.C., 1984 A review of artificial diagenesis during thermally enhanced recovery Clastic diagenesis 413–429.CrossRefGoogle Scholar
Kirk, J.S. Bird, G.W. and Longstaffe, F.G., 1987 Laboratory study of the effects of steam-condensate flooding in the Clearwater Formation: High temperature flow experiments Can Soc Petrol Geol 35 34–47.Google Scholar
McHardy, W.J. Birnie, A.C. and Wilson, M.J., 1987 Scanning electron microscopy A handbook of determinative methods in clay mineralogy London Blackie 174–208.Google Scholar
McHardy, W.J. Wilson, M.J. and Tait, J.M., 1982 Electron microscope and X-ray diffraction studies of filamentous illitic clay from sandstones of the Magnus Field Clay Miner 7 23–29 10.1180/claymin.1982.017.1.04.CrossRefGoogle Scholar
Nadeau, P.H. and Hurst, A., 1991 Application of back-scattered electron microscopy to the quantification of clay mineral microporosity in sandstones J Sed Petrol 61 921–925.Google Scholar
Pallatt, N. Wilson, M.J. and McHardy, W.J., 1984 The relationship between permeability and the morphology of diagenetic il-lite in reservoir rocks J Petrol Technol 36 2225–2227 10.2118/12798-PA.CrossRefGoogle Scholar
Waxman, M.H. and Smits, L.J.M., 1968 Electrical conductivities in oil-bearing shaly sands Soc Petrol Eng J 243 107–122 10.2118/1863-A.CrossRefGoogle Scholar
Wilson, M.D. and Pittman, E.D., 1977 Authigenic clays in sandstones: Recognition and influence on reservoir properties and paleo-environmental analysis J Sed Petrol 47 3–31.Google Scholar