Clay Minerals in Petroleum Reservoir Sands and Water Sensitivity Effects
The ability of some petroleum reservoir sands to conduct oil is decreased by interaction of the porous rock with water, usually water fresher than that coexisting with oil in rock interstices. Shales penetrated by drilling operations may swell upon interaction with relatively fresh water drilling liquids. The question of the relation of specific clay mineral content to reservoir sand water sensitivity has not been investigated in detail by other workers, although bentonitic clays often have been considered responsible.
A selection of 90 core samples from widely scattered American oil fields has been analyzed for clay mineral content. Reservoirs of known water sensitivity history and others where no such problem exists are represented by the samples. Modern X-ray diffraction techniques were employed to determine clay mineral types, lattice expandability, and approximate amounts present. The main purpose was to test the hypothesis that there exists a direct relationship between content of 3-sheet, glycerol-expandable clay minerals and water-sensitive behavior.
It was found that water sensitivity can be predicted with surprising accuracy by measuring the intensity of the X-ray diffraction peak of the glycerol-expanded basal plane spacing. Samples producing “moderate” or greater intensities of the glycerol-expanded peak were taken from sands that exhibited economically serious water-sensitive behavior. Large concentrations of nonexpandable kaolin, chlorite, and mica clay minerals did not produce serious water sensitivity effects in the absence of expandable minerals.
A selection of samples from West Texas sands of Permian age were the only samples older than the Mesozoic found to contain expandable clay minerals. These expanded anomalously, possibly as a result of interstratification. The characteristic clay mineral suite might be employed as a geological marker to identify the Yates and Queen sands over a wide geographical area in Pecos, Ward, and Winkler counties of West Texas.
A possible mechanism of the swelling of clay particles lining reservoir rock pores is discussed in terms of osmotic and Donnan membrane effects as applied to intraparticle swelling. The swelling of expandable clay mineral particles upon contact with relatively fresh water is postulated as the most general cause of water sensitivity difficulties encountered in petroleum production operations. Swollen particles restrict flow in rock pores, and minute, expanded lamellae break away to be dispersed in water within a pore and restrict flow further when they lodge in pore constrictions. Non-expandable clay mineral grains do interact specifically with water but are incapable of swelling and disintegrating to the same degree as those grains containing expandable minerals.
Unable to display preview. Download preview PDF.
- Baptist, O. C., Smith, W. R., Cordiner, F. S., and Sweeney, S. A. (1952) Physical properties of sands in the Frontier Formation, Big Horn Basin, Wyoming: Wyoming Geological Association Guidebook, Seventh Annual Field Conference, pp. 67–73.Google Scholar
- Baptist, O. C., and Sweeney, S. A. (1954) The effect of clays on the permeability of reservoir sands to waters of different saline contents: Pacific Coast Regional Conference on Clays and Clay Technology, June 25–26, 1954, Berkeley, California, this volume, p. 505.Google Scholar
- Barshad, I. (1950) The effect of the interlayer cations on the expansion of the mica type of crystal lattice: Am. Mineral., vol. 35, pp. 225–238.Google Scholar
- Bertness, T. A. (1953) Observations of water damage to oil productivity: A.P.I. Drilling and Production Practice, pp. 287–299.Google Scholar
- Brindley, G. W., and Robinson, K. (1951) The chlorite minerals. Chap. VI: Mineralogical Society of Great Britain Monograph, London, pp. 173–198.Google Scholar
- Brown, G., and MacEwan, D. M. C. (1951) X-ray diffraction by structures with random interstratification. Chap. XI: Mineralogical Society of Great Britain Monograph, London, pp. 266–284.Google Scholar
- Cardwell, W. T., Jr. (1954) Swelling clay identification: Pacific Coast Regional Conference on Clays and Clay Technology, June 25–26, 1954, Berkeley, California, this volume, p. 482.Google Scholar
- Collingwood, D. M., and Bethancourt, R. J. (1953) Waterflooding in North Government Wells Field, Duval County, Texas: Trans. A.I.M.E., vol. 198, pp. 157–164.Google Scholar
- Fancher, G. H., Lewis, J. A., and Barnes, K. B. (1933) Some physical characteristics of oil sands: Min. Ind. Expt. Sta. Bulletin 12, Penn. State College, pp. 65–171.Google Scholar
- Foster, M. D. (1953) Geochemical studies of clay minerals. II. Relation between ionic substitution and swelling in montmorillonites: Am. Mineral., vol. 38, p. 994–1006.Google Scholar
- Hughes, R. V., and Pfister, R. J. (1947) Advantages of brines in secondary recovery of petroleum by waterflooding: Trans. A.I.M.E., vol. 170, pp. 187–201.Google Scholar
- Johnston, N., and Beeson, C. M. (1945) Water permeability of reservoir sands: Trans. A.I.M.E., vol. 160, pp. 43–55.Google Scholar
- Marshall, C. E. (1949) Colloid chemistry of the silicate minerals: New York, Academic Press, 195 pp.Google Scholar
- Mathieson, A. McL., and Walker, G. F. (1954) The crystal structure of normal and partially-dehydrated Mg-vermiculite: Acta Crystallographica, vol. 7 (abstract), pp. 631–632.Google Scholar
- Muskat, M. (1949) Physical principles of oil production: New York, McGraw-Hill, 922 pp.Google Scholar
- Nahin, P. G., Merrill, W. C., Grenall, A., and Crog, R. S. (1951) Mineralogical studies of California oil-bearing formations: Trans. A.I.M.E., vol. 192, pp. 151–158.Google Scholar
- Nowak, T. J., and Krueger, R. F. (1951) Effect of mud filtrates and mud particles upon the permeabilities of cores: A.P.L Drilling and Production Practice, pp. 164–181.Google Scholar
- Walker, G. F. (1951) Vermiculites and some related mixed-layer minerals. Chap. VII: Mineralogical Society of Great Britain Monograph, London, pp. 199–223.Google Scholar