Dispersed Organic Matter Vitrinite Reflectance Accreditation Program (DOMVR)
Six (6) samples ground to 2-3 mm have to be prepared for petrographic analyses following ISO Standards 7404-2 prior to the measurement of vitrinite reflectance for entering the program.
The ASTM D7708-11 (2011) should be followed for the measurement of vitrinite reflectance of dispersed organic matter. Additional instructions are provided:
- The parameter to be evaluated is mean vitrinite random reflectance percentage, regardless the maceral sub-group. No huminite/vitrinite (ICCP, 1998; Sýkorová, et al., 2005) distinction applies as a function of coalification. The measurements to be made are of vitrinite reflectance using a light train without a polar and without stage rotation.
- The values reported should be the result of averaging at least 50 readings. No less than 30 values should be measured in the samples with scarce suitable particles.
- If other components such as recycled vitrinite, other macerals or contaminants are measured during the course of analysis, please make sure that they are excluded from the mean and standard deviation provided. Set of values in which the standard deviation is higher than the Ro value multiplied by 0.15 would not be acceptable. If this is the case in your set you are very likely providing values for a mixture of populations (recycled and rank vitrinite, inertinite and vitrinite, or supressed vitrinite and vitrinite). Please select the rank vitrinite before sending the results to the organizer.
At the conclusion of the exercise, the results from all participating petrographers are pooled. A statistical evaluation identifies those petrographers whose results do not fall within acceptable limits of departure from the group mean or that report results which are consistently higher or lower than the group mean (see Statistical Evaluation in Detail).
Petrographers who are not accredited in dispersed organic matter vitrinite reflectance have to perform six (6) complete analyses. These six sets of analyses will then form the petrographer’s new data file that will be statistically assessed and to which all subsequent analyses are added and evaluated.
International Committee for Coal and Organic Petrology, (ICCP), 1998. The new vitrinite classification (ICCP System 1994). Fuel 77, 349–358.
Sýkorová, I., Pickel, W., Christianis, K., Wolf, M., Taylor, G.H., Flores, D., 2005. Classification of huminite—ICCP System 1994. International Journal of Coal Geology 62, 85–106.
ASTM D7708-11, 2011. Standard Test Method for Microscopical Determination of the Reflectance of Vitrinite Dispersed in Sedimentary Rocks. Annual book of ASTM standards: Petroleum products, lubricants, and fossil fuels; Gaseous fuels; Coal and Coke, sec. 5, v. 5.06: ASTM International, West Conshohocken, PA, p. 823-830.