Speaker: Brian Cardott

Topic: Introduction to Vitrinite and Bitumen Reflectance as Thermal Maturity Indicators

Abstract:       Hydrocarbon source rocks are evaluated based on organic matter content (amount by total organic carbon), type (oil and gas generative), and thermal maturity. Thermal maturity is used to determine the zones of hydrocarbon generation and preservation. These zones are then applied to shale resource systems (unconventional resource plays). Optical thermal maturity parameters include vitrinite reflectance, bitumen reflectance, graptolite reflectance, and alginite fluorescence. Vitrinite reflectance is considered the “gold standard” thermal maturity parameter for shale, with advantages such as requiring a small amount of sample, inexpensive, quantitative and reproducible. However, there are sources of error that may complicate the analysis, such as caving contamination, drilling mud additives, weathering, vitrinite-like organic matter, too few measurements, and sample handling (discussed in Hackley and Cardott, 2016, and Cardott and Comer, 2021). Most of the presentation will cover the sources of error in measuring vitrinite and bitumen reflectance. The presentation expands on the material presented in Cardott (2012).

            The presentation will answer the following questions:

  1. What are vitrinite and bitumen?
  2. What are vitrinite and bitumen reflectance?
  3. How are vitrinite and bitumen reflectance measured?
  4. What are some sources of error?
  5. How do you tell good data from bad data?

Bio: Brian retired from the Oklahoma Geological Survey in June 2021 after 40 years of service.

Brian established the Organic Petrography Laboratory (OPL) at the Oklahoma Geological Survey in 1981. His primary research involved gas shales and tight oil (primarily the Late Devonian–Early Mississippian Woodford Shale), coalbed methane, and the petrologic characterization of coals, hydrocarbon source rocks, and solid hydrocarbons (e.g., asphaltites and asphaltic pyrobitumens) of Oklahoma. 

Brian has written more than 70 articles and books on coal, coalbed methane, gas shales, unconventional energy resources, hydrocarbon source rocks, solid hydrocarbons, organic weathering, vitrinite reflectance, and graptolite reflectance.  His seminal publication on the Woodford Shale was published in 2021 as OGS Bulletin 152 (Cardott and Comer, 2021).

Cardott, B.J., and J.B. Comer, 2021, Woodford Shale (Upper Devonian to Lower Mississippian): From hydrocarbon source rock to reservoir: Oklahoma Geological Survey, Bulletin 152, 108 p. https://www.ou.edu/ogs/publications/bulletins

Brian is a member of The Society for Organic Petrology (serving as President, 1995-1996), International Committee for Coal and Organic Petrology, American Association of Petroleum Geologists (serving as President of the Energy Minerals Division, 2004-2005), Oklahoma City Geological Society, and Fort Worth Geological Society.