Predicting oil and gas compositional yields via chemical structure–chemical yield modeling (CS–CYM): Part 2 – Application under laboratory and geologic conditions

• Published in: Organic geochemistry Vol. 38; no. 2; pp. 306 - 322
• Main Authors: Walters, Clifford C., Freund, Howard, Kelemen, Simon R., Peczak, P., Curry, David J.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Oxford Elsevier Ltd 01.02.2007; Elsevier Science
• Subjects: Earth sciences; Earth, ocean, space; Exact sciences and technology; Geochemistry; experimental studies; models; open systems; reliability; chemical properties; closed systems; extrapolation; pyrolysis; materials; kerogen; prediction; temperature; kinetics
• ISSN: 0146-6380; 1873-5290
• DOI: 10.1016/j.orggeochem.2006.09.010

We have developed a method for calculating from first principles the amounts and composition of products resulting from the thermal decomposition of a solid complex carbonaceous material. Advanced solid state analysis provides chemical and property measurements for kerogen that are used to construct a representative model of its chemical structure (CS). These chemical structural models are then coupled with a chemical yields (CY) model that is based primarily on free radical reaction mechanisms. The combined model, CS–CYM offers the ability to predict the thermal conversion of kerogen under a wide range of heating rates and temperature. Results from laboratory heating experiments are compared with those calculated with CS–CYM and show excellent agreement with a variety of bulk physical and chemical properties, open and closed system pyrolysis yields and product compositions, and open system kinetics. The reliability of CS–CYM in predicting the thermal reactions that occur under laboratory conditions indicates that we have captured a significant portion of the thermal reaction mechanisms and pathways that occur in nature. Hence, we believe that CS–CYM approach provides a better prediction of the thermal chemistry that occurs under geologic conditions than extrapolation of experimental results conducted at much higher temperature and faster heating rates where reactions, product distributions and modes of expulsion may differ significantly from basinal processes.