Tracer Analyses Laboratories

The laboratories provide "state of the art"-methods for the determination of lowest concentrations of tracers in petroleum reservoir fluids. Several thousand tracer samples from reservoirs worldwide are prepared and analyzed in these laboratories every year. Beside these routine analyses, a continuous development of analytical methods for actual tracers and new tracer candidates is going on to provide "state of the art"-methods also in the future.
Contact

Dugstad, Øyvind

Deputy Head of Department / Section Head

Galdiga, Claus

Section Head

 

Methodology

Depending on the type of tracers, various types of sample preparation techniques are applied to selectively extract and pre-concentrate the tracer molecules prior to analysis. Important techniques used are ion exchange for charged compounds, solid phase extraction for organic molecules and adsorption/thermal desorption for volatile species.

The radioactive tracers are typically detected by liquid scintillation spectroscopy with ultra low-level liquid spectrometers. (See also "Measurement of Low Level Radioactive Samples").

Liquid Chromatography in combination with Electrochemical or Fluorescence Detection or Gas Chromatography in combination with Mass Spectrometers operated in different ionization modes are in use for detection of the chemical (non-radioactive) tracer compounds.

Analytical Instrumentation

  • 4 GC/MS (2 Fisons MD 800 and 2 Agilent 5973 MSD systems, both types can be operated in EI, NCI and PCI mode)
  • 1 GC/MSMS (Varian 1200L Triple Quadrupole)
  • 3 GC (5890 Hewlett Packard equipped with FID, ECD ELCD)
  • 3 Thermal Desorber (2 Perkin Elmer ATD 400, 1 Markes Ultra/Unity)
  • 3 HPLC (1 HP 1050 with Electrochemical Detector, 2 Agilent 1100 series with DAD and Fluorescence Detector
  • 1 Fluorescence Spectrophotometer (Varian Cary Eclipse)
  • 2 Ultra Low Level Liquid Scintillation Spectrometer (LKB/Wallac Quantulus 1220)
  • Advanced equipment for radiation detection (See also  "Measurement of Low Level Radioactive Samples")

Application

Fluorinated benzoic acids (FBAs) are typical compounds for tracing injection water. But also other organic acids have good tracing capability. Another popular water tracer is thiocyanate. Typical instrumentation for the determination of these compounds is GC/MS, GC/MSMS or HPLC in combination with various detectors. Many of these compounds can be detected in reservoir matrices in concentrations down to the low ppt level.

ife GC/MSMS for FBA analysis

Left: HPLC equipment for the analysis of water tracers. Right: GC/MSMS for FBA analysis.

 

ATDThe most popular gas tracers are perfluorinated cyclic hydrocarbons (PFCs). The reason for the popularity is their stability under difficult conditions and extremely good detectability on Electron Capture Detectors or Mass Spectrometers operated in the NICI-mode (negative ion chemical ionization). Gas samples are taken in the field on CATS (capillary adsorption tube samplers) and shipped by express services to our laboratories. There, up to 50 tubes can be automatically analyzed on one of our ATD (automated thermal desorber)-GC/MS systems. Typical PFC concentrations measured in reservoir gases are at the ppt level. This detection level can also be achieved in the presence of high concentrations of H2S.

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Overlay of chromatograms generated by an ATD-GC/MS system

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Capillary adsorption tube (CATS) sampler. - two tubes in series for quality ensurance purposes.

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