Micro- and Nano-Raman Spectroscopy

L. Borromeo1,2,*, U. Zimmermann1,2, S. Andò3, N. Egeland1,2, C. Toccafondi4, R. Ossikovski4, D. Bersani5, E. Garzanti3

1 Department of Petroleum Engineering, University of Stavanger, Norway, laura.borromeo@uis.no2 The National IOR Centre of Norway, University of Stavanger, Norway

3 Department of Earth and Environmental Sciences, University of Milano-Bicocca, Italy4LPICM, CNRS, Ecole Polytechnique, Université Paris Saclay, France5 Department of Physics and Earth Sciences, University of Parma, Italy

Raman SpectroscopyRAMAN SPECTROSCOPY IS AN INNOVATIVE, EFFICIENT, USER-FRIENDLYTECHNIQUE, REPRESENTING A POWERFUL TOOL TO CONFIDENTLYIDENTIFY MINERALS

• Non destructive technique, quickness and microscopic resolution (1-2 µm)

• No time-consuming

• No sample specific preparation (rocks, thin sections, micromounts, gas, liquid)IT CAN BE FRUITFULLY APPLIED TO MINERALOGY AND SEDIMENTARYPETROGRAPHY

The InVia Micro-Raman spectrometer, Renishaw

University of Milano Bicocca

Raman Spectra

200

Calcite crystal, Mexico

Aragonitic Algae, Maldives

Raman shift (cm-1)

281

714

1088

208 703

1087

707

200 1000800600400

RAMAN PEAK MINERAL

Position Chemistry/structure

WidthOrder-

disorder/structure

Intensity Quality/grainsize

Relative intensity Orientation of the crystal

Micro-Raman on silt

A new quantitative method to study silt-sizedgrains: light fraction of the Bengal shelf muds.

Raman shift (cm-1)200 400 600 800 1000 1200 1400

From L. Borromeo Master thesis

Micro - Raman on Flooded chalk

• Flooding with MgCl2 for c. 1.5 yearsat reservoir conditions (130°C, 1PV/day, 12 MPa effective stress)

• Mineralogical changes due to fluidinjection: when Mg2+ ions bond with(CO3)2- ions: magnesite or Mg-calcite will grow as new mineralphases.

Micro-Raman spectroscopy could identify the presence of magnesite along the core of the sample up to 4 cm from the injection surface.

From Borromeo et al., in prep

+High-resolution

Raman spectrometer

Chemical and structural analysis

Scanning probe microscope (SPM)

Nano-resolvedsurface mapping

TERS + AFM Nano-Raman

• Spatial resolution ~ 20 nm

• Raman signal

enhancement ~ x104-5

(Tip-Enhanced Raman Spectroscopy + Atomic Force Microscopy)

TERS AFM Raman spectrometer, Horiba

Ecole Polytechnique, Paris

Topography map

• Raman map: 4x4 µm2, step = 250 nm• For each pixel we acquired a TERS

spectrum

Tip-Enhanced Raman Spectroscopy measurements on chalk samples

324 cm-1

1096 cm-1

TERS + AFM Nano-Raman

Raman shift (cm-1)From Borromeo et al., in prep

Magnesite

Conclusions• Raman spectroscopy is a very efficient, user-friendly point-

analysis technique that with a quick, non-destructive sample preparation allows us to obtain accurate minerochemicalinformation of micro- to nano-metric minerals.

• Raman spectroscopy provides an innovative work perspective in petroleum exploration of unconventional reservoirs, such chalk, siltstones and shales.

Grazie a tutti!

For more information:• Andò S. & Garzanti E. (2013). Raman Spectroscopy in heavy-mineral studies. Geological Society, London

Special publications;• Andò S.,Vignola P., Garzanti E., (2011). Raman counting: a new method to determine provenance of silt.

Rendiconti Lincei, 22, Issue 4, 327-347;• Borromeo L., U. Zimmermann, S. Andò, G. Coletti, D. Bersani, D. Basso, P. Gentile, B. Schulz, E.

Garzanti. Raman Spectroscopy as a tool for magnesium estimation in Mg-calcite, submitted to JRS.

C. V. Raman, 1928