Kerogen Content and Maturity, Mineralogy and Clay Typing from DRIFTS Analysis of Cuttings or Core
- Michael M. Herron (Schlumberger Doll Research) | MaryEllen Loan (Schlumberger Doll Research) | Alyssa M. Charsky (Colorado School of Mines) | Susan L. Herron (Schlumberger Doll Research) | Andrew E. Pomerantz (Schlumberger Doll Research) | Marina Polyakov (Schlumberger Doll Research)
- Document ID
- Society of Petrophysicists and Well-Log Analysts
- Publication Date
- October 2014
- Document Type
- Journal Paper
- 435 - 446
- 2014. Society of Petrophysicists & Well Log Analysts
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- 400 since 2007
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Diffuse reflectance infrared Fourier-transform spectroscopy (DRIFTS) has recently been introduced and is currently being evaluated. It is a rapid, robust, and efficient technique for simultaneously quantifying kerogen and mineralogy from core and cuttings samples, both in the laboratory and at the wellsite. The technique quantifies mineralogy and kerogen content by measuring the vibrational absorbance due to chemical bonds. Core and cuttings samples from wells in unconventional reservoirs in North and South America were analyzed using a technique that solves for illite, smectite, kaolinite, and chlorite, in addition to nonclay mineral components and kerogen.
Samples were also analyzed for mineralogy by the more accurate but time consuming transmission dual-range Fourier-transform infrared spectroscopy technique and for total organic carbon (TOC) by LECO/coulometry. The results for both mineralogy and TOC compare very well.
The DRIFTS hydrocarbon signal at 2,800 to 3,000 cm-1 is due to the C–H bond vibrational modes of aliphatic hydrocarbons. This signal decreases in magnitude faster than the TOC decreases as kerogen matures. As a result, the ratio of TOC to the DRIFTS signal can be used as a new estimate of organic maturity. Examples are presented to show the agreement with estimates from vitrinite reflectance or Tmax for samples with Ro ranging from 0.6 to 1.35%. Full DRIFTS analysis including sample preparation generally takes less than 20 minutes for any mud type, which allows the technique to keep up with the drilling at the wellsite.
|File Size||9 MB||Number of Pages||12|