Challenges in Using Programmed Pyrolysis Data From Mature to Late Mature Source Rocks to Evaluate Source Rock Capabilities and Free Hydrocarbons in Unconventional Resource Plays

Abstract

Programmed pyrolysis was designed to characterize petroleum potential in source rocks as well as gauge the level of organic maturity for immature to marginally mature organic rich rocks. Over the years programmed pyrolysis has been used with mature to late mature fine grain rocks to help characterize not only generative capability and maturity, but productivity. Examination of pyrolysis data from a variety of major source rocks with different levels of maturity and lithology suggest the pyrolysis results are more complicated and can be easily misinterpreted. The pyrolysis S1 measurement is used to evaluate generated hydrocarbons but can be heavily impacted by volatile loss and carbon based mud additives. S2, which represents the non-generated hydrocarbons (kerogen), appears to contain generated hydrocarbons which have not been thermally removed during the S1 temperature stage. Much caution should be used in evaluating programmed pyrolysis data to determine source rock type, maturity, and productivity. Pyrolysis is a blunt instrument and the addition of elevated staining from generated hydrocarbons in fully mature source rocks or potential contaminants need to be considered when evaluating pyrolysis data. Despite these issues, programmed pyrolysis data is the most commonly applied tool for organic matter evaluation, in both early and late mature samples. This widely available measurement can be applied effectively to evaluate both unconventional resource plays and source rock potential with the proper data quality checks.

AAPG Datapages/Search and Discovery Article #90259 ©2016 AAPG Annual Convention and Exhibition, Calgary, Alberta, Canada, June 19-22, 2016