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Title: Assessing thermal maturity beyond the reaches of vitrinite reflectance and Rock-Eval pyrolysis: A case study from the Silurian Qusaiba formation

Authors:
; ORCiD logo; ; ; ; ;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
Sponsoring Org.:
FOREIGN
OSTI Identifier:
1397310
Resource Type:
Journal Article
Resource Relation:
Journal Name: International Journal of Coal Geology; Journal Volume: 180; Journal Issue: C
Country of Publication:
United States
Language:
ENGLISH

Citation Formats

Cheshire, Stephen, Craddock, Paul R., Xu, Guangping, Sauerer, Bastian, Pomerantz, Andrew E., McCormick, David, and Abdallah, Wael. Assessing thermal maturity beyond the reaches of vitrinite reflectance and Rock-Eval pyrolysis: A case study from the Silurian Qusaiba formation. United States: N. p., 2017. Web. doi:10.1016/j.coal.2017.07.006.
Cheshire, Stephen, Craddock, Paul R., Xu, Guangping, Sauerer, Bastian, Pomerantz, Andrew E., McCormick, David, & Abdallah, Wael. Assessing thermal maturity beyond the reaches of vitrinite reflectance and Rock-Eval pyrolysis: A case study from the Silurian Qusaiba formation. United States. doi:10.1016/j.coal.2017.07.006.
Cheshire, Stephen, Craddock, Paul R., Xu, Guangping, Sauerer, Bastian, Pomerantz, Andrew E., McCormick, David, and Abdallah, Wael. Sat . "Assessing thermal maturity beyond the reaches of vitrinite reflectance and Rock-Eval pyrolysis: A case study from the Silurian Qusaiba formation". United States. doi:10.1016/j.coal.2017.07.006.
@article{osti_1397310,
title = {Assessing thermal maturity beyond the reaches of vitrinite reflectance and Rock-Eval pyrolysis: A case study from the Silurian Qusaiba formation},
author = {Cheshire, Stephen and Craddock, Paul R. and Xu, Guangping and Sauerer, Bastian and Pomerantz, Andrew E. and McCormick, David and Abdallah, Wael},
abstractNote = {},
doi = {10.1016/j.coal.2017.07.006},
journal = {International Journal of Coal Geology},
number = C,
volume = 180,
place = {United States},
year = {Sat Jul 01 00:00:00 EDT 2017},
month = {Sat Jul 01 00:00:00 EDT 2017}
}
  • Organic geochemical and petrographic analyses of potential source rock samples taken from 30 drill holes penetrating Cenozoic basins of the Basin and Range province in eastern Nevada indicate two distinct trends in thermal maturity, as expressed by vitrinite reflectance equivalent (VRE). VRE is any coal rank or other thermal maturity parameter converted to its equivalent in vitrinite reflectance units using correlation charts. One trend is an increase with depth from about 2% VRE at 500 ft to 5% VRE at 12,000 ft, which is supermature with respect to oil generation. The other trend consists of mature rocks that have amore » nearly uniform VRE of about 0.7% ({plus minus}0.2%) from the near surface to a depth of 12,000 ft. Both the lower and the higher range geothermal gradients measured across the area, about 0.4 to 2.5F/100 ft (8 to 45C/km), correspond with the mature and supermature trends, respectively. The authors attribute these trends to two major thermal environments common within these Cenozoic basins. The supermature trend results from high geothermal gradients found near igneous intrusions, faulted contacts of uplifted metamorphic core complexes, or other heat sources. The mature trend characterized by near-zero VRE gradients results from groundwater recharge which produces cool temperatures at depth and low geothermal gradients. These generalizations should be applied with caution to any specific area because they are based on a composite VRE depth curve and, in some localities, may not represent realistic interpretation. However, VRE profiles within individual drill holes within the region generally follow one of these trends.« less
  • Because of the absence of vitrinite in lower Paleozoic sediments, the reflectance of pyrobitumen is used as an indicator of thermal maturation. A new technique of preparing organic matter permits discrimination among types of zooclasts and solid bitumen, including pyrobitumen, and leads to more precise reflectance-histograms. Studies of organic matter from Ordovician-Silurian strata of Anticosti Island show that reflectance of zooclasts is different from that of solid bitumen, and that each group of the following zooclasts, chitinozoans, graptolites, and scolecodonts, has a specific reflectance evolution path with increasing depth. On a logarithmic scale, the paths of the three groups ofmore » zooclasts are linear, highly correlated, and converging. However, reflectance of solid bitumen is not linear throughout the range studied; solid bitumen becomes linear only where the reflectance is greater than 0.75%. Comparing the relations between zooclasts and solid bitumen with the vitrinite-solid bitumen correlation in the literature suggests that a hypothetical vitrinite evolution line in the Anticosti Island basin should be subparallel with that of chitinozoans and graptolites, but 0.4-0.8% lower, in the 1-2% range. However, scolecodonts and vitrinite should have the same reflectance at 1%, but scolecodont reflectance should be slightly (0.2%) higher for a vitrinite reflectance of 2%. 6 figures, 3 tables.« less
  • Forty-four subsurface samples of the nodular shale were collected from 14 selected wells located mostly between the Playa del Rey and Crescent Heights oil fields. Sites were selected to give the widest available range of sample depth and temperature where present burial depths are maximal, and where geothermal gradients are firmly established. Median random reflectance (%R/sub 0/) of first-cycle vitrinite is least in the shallowest samples, clusters about 0.24% in the deeper samples, and exceeds 0.30% only in the deepest and hottest samples. Extremes in the range of measured median %R/sub 0/ are tabulated below with corresponding extremes of samplemore » temperatures, depths, Time-Temperature Indices (TTI), and calculated %R/sub 0/ equivalents of the TTI values. All measured values of R/sub 0/ are significantly depressed compared to other maturity criteria. Significantly, second-cycle and oxidized vitrinite from these same samples show normally elevated reflectance. Eight of the samples processed for reflectance measurements were analyzed for total organic carbon content, which ranges from 2.21 to 9.41%. Most of the organic detritus is amorphous degraded algal material; less than 10% is structured vitrinite. Thermal alteration index values for the amorphous material range from 2 to 2 1/2, corresponding with hypothetical conversion R/sub 0/ values between 0.45 and 0.75%, again notably higher than the measured values. The ratios of extractable hydrocarbons to TOC in the 8 samples suggest mature levels of thermal evolution, as do carbon preference indices of 0.93 and 1.14 from extracts of 2 samples.« less
  • The Methylphenanthrene Index (MPI-1) has been calibrated against vitrinite reflectance using Australian Carboniferous, Permian, Jurassic and Tertiary sediments and coals containing terrestrial organic matter. The correlation obtained was slightly different from that found previously and has resulted in an extension of the relationship to lower maturation levels (vitrinite reflectance = 0.5% R/sub 0/). In this sample set the Methylphenanthrene Distribution Factor (Kvaldheim et al., Geochim. Cosmochim. Act 51, 1883-1888, 1987) showed a poorer correlation to vitrinite reflectance than MPI-1. Hydrogen-rich organic matter from an immature marine sequence gave anomalously high Methylphenanthrene Indices and confirms a source control on the indexmore » at low maturation levels. The index has been used to confirm the low maturity of some Australian terrestrial oils and to determine the degree of maturation of organic matter and oils in Proterozoic sediments.« less