Vitrinite Standard ASTM WK24192 to Aid in Hydrocarbon Exploration
August 13, 2009 // Published as a news service by IHS
ASTM International Committee D05 on Coal and Coke is developing ASTM WK24192 - Test Method for Microscopical Determination of the Reflectance of Vitrinite Dispersed in Sedimentary Rocks.
Measuring the reflectance of vitrinite dispersed in sedimentary rocks is a tool used for determining thermal maturity in hydrocarbon exploration, basin modeling and other geological applications, according to ASTM.
Despite this, experts said there is not a consensus standard for making these measurements.
The proposed standard is being developed by a task group that includes experts from the International Committee for Coal and Organic Petrology and the Society for Organic Petrology.
ASTM WK24192 is under the jurisdiction of Subcommittee D05.28 on Petrographic Analysis of Coal and Coke.
Paul Hackley, chair of Subcommittee D05.28, said vitrinite is the coalified remains of woody plant material, which is found in nearly all sedimentary rocks formed since the evolution of vascular land plants about 400 million years ago.
The vitrinite reflectance changes systematically with the amount of burial and heating that the rock experiences, he said.
"Therefore, vitrinite reflectance can be used as a thermometer by which to infer the thermal maturity of the rocks it is contained in," Hackley said. "This has very important practical implications in hydrocarbon exploration as economic accumulations usually are found only within certain ranges of thermal maturity, often called oil and gas windows."
According to Hackley, petrographers can generally measure similar values of dispersed vitrinite reflectance in interlaboratory exercises, but disparities exist and a consensus standard will improve agreement by providing a common methodology and a set of guidelines for analysts to follow.
Source: ASTM International.