Programmed-pyrolysis Derived Petroleum Yield Determinations Calibrated with Hydrous Pyrolysis: a Case Study of Green River Source Rocks
Tim E. Ruble and Michael D. Lewan
Total organic carbon (TOC) and programmed pyrolysis data are easily determined and widely applied to assess unconventional shale-oil targets. These data may be used to map and constrain the generative potential, kerogen type, and thermal maturity of source rocks at the well- to basin-scale. In addition, by making some assumptions regarding the original TOC and hydrogen index of thermally immature source rocks, yield calculations can be applied to estimate the extent of petroleum generation and the volumes and expulsion efficiency of mature source rocks. In this study, we used Green River shale samples and various programmed pyrolysis parameters to estimate the volumes of oil generated from a temperature series of hydrous pyrolysis experiments. These experiments were conducted for 72 hours at temperatures between 160? to 365?C, which represents a maturity range from pre-bitumen generation to the end of oil generation. Spent source rock material and solvent extracted samples were both analyzed by programmed pyrolysis and the calculated oil generation yields were compared. These calculated oil yields were also calibrated against measured oil volumes recovered from the various hydrous pyrolysis experiments. Although hydrous pyrolysis oil yields at the end of oil generation are similar to the calculated estimates, these measured oil yields are significantly lower than those predicted at the earlier stages of oil generation. In contrast, comparison of total product yields from hydrous pyrolysis (bitumen+oil+gas) shows good correlation with programmed pyrolysis derived calculated oil yields across the entire maturation range. These relationships indicate that calculated yields from programmed pyrolysis need to be calibrated to hydrous pyrolysis yields for more realistic determinations of oil charge in evaluating conventional and unconventional oil plays.
AAPG Search and Discovery Article #90169©2013 AAPG Rocky Mountain Section 62nd Annual Meeting, Salt Lake City, Utah, September 22-24, 2013