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TitleRevised models for determining TOC in shale play: example from Devonian Duvernay Shale, Western Canada Sedimentary Basin
AuthorWang, P; Chen, Z; Pang, X; Hu, K; Sun, M; Chen, X
SourceMarine and Petroleum Geology vol. 70, 2016 p. 304-319, https://doi.org/10.1016/j.marpetgeo.2015.11.023
Year2016
Alt SeriesEarth Sciences Sector, Contribution Series 20150433
PublisherElsevier
Documentserial
Lang.English
Mediapaper; on-line; digital
File formatpdf
ProvinceAlberta
NTS83A; 83B; 83G; 83H; 83F; 83J; 83K; 73D; 82P
Areacentral Alberta; Western Canada Sedimentary Basin
Subjectsfossil fuels; mathematical and computational geology; shales; well log analysis; source rocks; modelling; gas; gas generation; total organic carbon (TOC); Revised (delta)logR method; Devonian
Illustrationsformulae; graphs; location maps; tables; histograms
ProgramShale-hosted petroleum ressource assesment, Geoscience for New Energy Supply (GNES)
AbstractDetermination of total organic carbon (TOC) is essential in unconventional shale resource play evaluation. Indirect method, such as petrophysical approach, can provide a fast, convenient and cost efffective means for TOC estimation from well logs. Among the publically available approaches, the DlogR method is a popular one in conventional source rock evaluation and has been applied to unconventional resource play evaluation by many practitioners. Careful examination of the method finds that improvements can be made for a better TOC estimation with relaxed limitations. This study proposes the following revisions on the original DlogR method: 1) allowing estimation of petrophysical parameters from the targeted source rock rather an assumed linear approximation, 2) using additional logs to improve TOC prediction, and 3) replacing LOM (level of organic metamorphism unit) with a more commonly used thermal indicator
Tmax for convenience. Depending on data or preference, the choice of using different porosity logs (density versus sonic) and parameter estimation methods (cross-plot method versus data-driven approaches) makes the revised method flexible for application. We present the revisions along with application examples from the Devonian Duvernay Shale in the Western Canada Sedimentary Basin to
demonstrate the application of the improved DlogR method in shale gas evaluation. Comparison of the results from the revised method and the original one reveals that the revised models provide better and unbiased estimates of TOC with a higher correlation coefficient and bell-shaped residues centered at zero.
Summary(Plain Language Summary, not published)
Determination of total organic carbon (TOC) is essential in unconventional shale resource play evaluation. Among the publically available approaches, the ?logR method is a popular method in source rocks evaluation and has been applied to unconventional play by many practitioners. Careful examination of the method finds that improvements can be made for a better TOC estimation. This study proposes the following revisions on the original method: 1) allowing estimation of petrophysical parameters from targeted source rock, 2) using additional logs to improve TOC prediction, and 3) replacing LOM (Level of Maturity) with a more commonly used thermal indicator Tmax. Depending on data or preference, the choice of using different porosity logs and parameter estimation methods makes the revised method flexible for application. We present the method with application examples from the Devonian Duvernay Shale in the Western Canada Sedimentary Basin to demonstrate the improved ?logR method.
GEOSCAN ID297604