Consultancy and Analytical Services Offered

 
    Via Jennifer Huggett, Petroclays offers a high level of expertise in clastic geology, applied particularly to:  
  • shale petrology
  • understanding the controls of clastic reservoir quality
  • understanding the causes of reservoir damage caused by drilling or production
  • understanding the causes of reactive shales and predicting their distribution
  • quantifying mineralogy using X-ray diffraction and microscopy
  • quantifying primary, secondary and micro porosity using microscopy
  • quantifying swelling clay and other problem minerals for geotechnical studies


Analytical Techniques Employed


 
  X-Ray Diffraction Analysis (XRD)
  • Preparation and scanning of oriented clay mounts (<2µm or <4µm) and powders (for whole rock analysis)
  • Provision of annotated traces
  • Full interpretation of the traces, and semi-quantitative estimation of mineral percentages
Instrumentation
The samples are analysed with a fully automated Phillips 1820 X-ray diffractometer, using Cu Ka radiation and a variable slit system.
Clay samples are generally scanned untreated (2-40° 2Ø), glycolated (2-26° 2Ø), and heated (400°C and 550°C).
Whole rock powders are scanned from 2-70 2Ø.  Scanning is normally at a rate of 0.02°/ minute.
Click the image below for an example of XRD analysis
XRD traces
More about XRD
 
 
         
 
   
Comprehensive mineralogical analysis and diagenetic interpretation of samples (outcrop, core, sidewall core or cuttings). The degree of detail and the emphasis being dependent upon the client's requirements. Petroclays offers expertise in clastics, including volcaniclastics. Work can also be carried out on limestones.
The optical microscopy service includes:
 
 
  • Thin section preparation to a very high standard, using either clear or blue dyed epoxy resin.
  • Selective mineral staining for carbonates and feldspars.
  • Illustration by annotated digital images.
  • Detailed thin section analysis with lithological and textural analysis, description of authigenic and detrital minerals including any potential formation damage hazards, quantification (point counting to 300 using a modified version of the ExxonMobil classification), interpretation of diagenetic history, pore types and assessment of porosity/permeability characteristics.
 
Instrumentation
Olympus BX41 optical microscope with Swift automatic point counter and Q Imaging image capture.
 
Click on image for an example of optical microscopy images Example of thin section
 
 
  • Preparation of samples with either gold or carbon (for samples requiring quantitative analysis)
  • Illustration by monochromatic digital images
  • Description of textures, mineral habits and crystallinity, pore geometry and the nature of cement/porosity relationships
  • Semi-quantitative energy dispersive X-ray analysis for conventional fracture surface SEM samples
  • Quantitative energy dispersive or wave-length dispersive X-ray analysis for polished samples, this can be combined with automated analysis of pre-selected data points, or a grid of points
Click on image for an example of SEM images Example of SEM imaging
 


Fracture surface, secondary electron imaging
, the 'conventional' mode of SEM, is used for examining grain and cement textures. Semi-quantitative energy dispersive X-ray analyses can be obtained for individual particles larger than 1-2 µm
Click for more on Fracture Surface Secondary Electronic Imaging

Back-Scattered Electron Microscopy (BSEM) is used for petrographic study and can be used to study the mineralogy, textures and fabric in fine grained rocks such as mudstones as well as in coarser grained rocks. BSEM petrography has an additional advantage over light microscopy in that if the SEM has an X-ray analysis facility then qualitative or quantitative analyses of the mineral components can be obtained.
Other successful industrial applications of BSEM include the study of scales and corrosion products.
Click for more on Back-Scatterd Electron Microscopy



Click on image for an example of BSEM images Example of BSEM imaging
   
Instrumentation
The Scanning Electron Microscopes used are a Zeiss EVO (for high quality chemical analysis), aZeiss Ultra Plus (for high resolution imaging and quantitative analysis) and a LEO 1455VP for routine analysis.  All three instruments are fitted with Oxford Instruments INCA x-ray analytical softwatre.


Other Services

Petroclays can also arrange to provide
 
  • transmission electron microscopy
  • cathodluminescence microscopy
  • EELs analysis
  • oxygen and carbon stable isotope analysis
  • K/Ar age dating
  • ICP-AES chemical analysis
  • XRF chemical analysis
Where third parties are used, these are always highly reputable suppliers.