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The potential reactivity of reservoir clays was evaluated by experimentation, and their natural distribution was reviewed. Samples of the principal authigenic clay minerals occurring in sandstone reservoirs (illite, smectite, mixed-layer illite/smectite, kaolinite and chlorite) were separated from preserved cores. The separated samples were then exposed to a range of aqueous reagents (acids, alkalis and complexing agents) in an extensive matrix of batch and flow experiments at temperatures up to 80 C (atmospheric pressure). As different clay minerals react in different ways to various solutes, it is important to know which clays are present in potential reservoirs. Kaolinite occurs widely in shallow reservoirs, especially in feldspathic sands where there has been significant meteoric infiltration. Illitic reservoirs are to be anticipated wherever any but the most mature and closed sands have been subjected to temperatures over 100 C (mixed layer illite/smectites at slightly lower temperatures). Smectite and chlorite form under rather specialised conditions, and any predictive ability requires detailed knowledge of facies development and contemporaneous volcanicity.

Additional information

Authors: CURTIS C D, University of Sheffield, Department of Geology, Sheffield (GB);HUGHES C R, University of Sheffield, Department of Geology, Sheffield (GB)
Bibliographic Reference: EUR 13141 EN (1990) 158 pp., MF, ECU 8
Availability: (2)
Record Number: 199011853 / Last updated on: 1994-12-02
Original language: en
Available languages: en