Wettability of Rock Surfaces of mature oil fields in view of their posterior use

(Text nur in Englisch verfügbar)

Introduction

For many oil and gas field applications the knowledge of the reservoir parameters is crucial. This includes the wettability of the reservoir rock. Sandstones are initially water-wet, but their wettability can alter during the life time of a reservoir due to asphaltene precipitation and other mechanisms. Especially in view of reducing the residual oil content and for a safe storage, e.g. of CO2 and hydrogen, capillary trapping may be jeopardized due to reduced water wetting.  The wettability of a surface depends  on the interfacial  energies  of the interacting phases on the one hand and on the roughness of the solid surface on the other. In recent years, the institute utilizes microfluidics for flooding experiments at pore scale. The micromodels consist of glass and silicon with flat and smooth surfaces that can be chemically modified from water to oil-wet in accordance with the naturally occurring transformations. In order to improve this technology even further for matching real rock properties, the roughness of this surfaces shall be taken into account in this work. This study shall give an overall view on the influence of roughness on the predominant interfacial properties.

Scope

Based on the above introduction, the proposed thesis should include the following:

  1. Give the introduction into wettability, contact angle and their dependency on the surface roughness.
  2. Summarize the state of the art of wettability of common sandstone reservoir rocks and their composing minerals.
  3. Define roughness, how it can be measured and describe how a (glass) surface can be treated to feature a specific roughness. Compare different methods and their precision.
  4. Determine  the surface roughness of natural minerals and of reservoir rocks.
  5. Determine the contact angle on surfaces of defined roughness and give an interpretation based on studies available in literature including other properties that are also changed.

References

  • W. Abdallah, J. S. Buckley, A. Carnegie, J. Edwards, B. Herold, E. Fordham, A. Graue, T. Habashy, N. Seleznev, C. Signer, et al., Oilfield Review 2007, 19, 44–61.
  • R. N. Wenzel, Ind. Eng. Chem. 1936, 28, 988–994.
  • A. B. D. Cassie, S. Braxter, Trans. Faraday Soc. 1944, 40, 546–551.
  • P. Jaeger, A. Pietsch, Journal of Petroleum Science and Engineering, 2009, 64, 20-24.