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Compound Specific Hydrogen Isotope Composition of Type II and III Kerogen Extracted by Pyrolysis-GC-MS-IRMSThe use of Hydrogen (H) isotopes in understanding oil and gas resource plays is in its infancy. Described here is a technique for H isotope analysis of organic compounds pyrolyzed from oil and gas shale-derived kerogen. Application of this technique will progress our understanding. This work complements that of Pernia et al. (2013, this meeting) by providing a novel method for the H isotope analysis of specific compounds in the characterization of kerogen extracted by analytically diverse techniques. Hydrogen isotope analyses were carried out entirely "on-line" utilizing a CDS 5000 Pyroprobe connected to a Thermo Trace GC Ultra interfaced with a Thermo MAT 253 IRMS. Also, a split of GC-separated products was sent to a DSQ II quadrupole MS to make semi-quantitative compositional measurements of the extracted compounds. Kerogen samples from five different basins (type II and III) were dehydrated (heated to 80 C overnight in vacuum) and analyzed for their H isotope compositions by Pyrolysis-GC-MS-TC-IRMS. This technique takes pyrolysis products separated via GC and reacts them in a high temperature conversion furnace (1450 C) which quantitatively forms H2, following a modified method of Burgoyne and Hayes, (1998, Anal. Chem., 70, 5136-5141). Samples ranging from approximately 0.5 to 1.0mg in size, were pyrolyzed at 800 C for 30s. Compounds were separated on a Poraplot Q GC column. Hydrogen isotope data from all kerogen samples typically show enrichment in D from low to high molecular weight compounds. Water (H2O) average deltaD = -215.2 (V-SMOW), ranging from -271.8 for the Marcellus Shale to -51.9 for the Polish Shale. Higher molecular weight compounds like toluene (C7H8) have an average deltaD of -89.7 0/00, ranging from -156.0 for the Barnett Shale to -50.0 for the Monterey Shale. We interpret these data as representative of potential H isotope exchange between hydrocarbons and sediment pore water during formation within each basin. Since hydrocarbon H isotopes readily exchange with water, these data may provide some useful information on gas-water or oil-water interaction in resource plays, and further as a possible indicator of paleo-environmental conditions. Alternatively, our data may be an indication of H isotope exchange with water and/or acid during the kerogen isolation process. Either of these interpretations will prove useful when deciphering H isotope data derived from kerogen analysis. More experiments are planned to discern these two or other possible scenarios.
Document ID
20130013718
Acquisition Source
Johnson Space Center
Document Type
Abstract
Authors
Socki, Richard A.
(Jacobs Technology, Inc. Houston, TX, United States)
Pernia, Denet
(BP America, Inc. Houston, TX, United States)
Evans, Michael
(Texas A&M Univ. College Station, TX, United States)
Fu, Qi
(NASA Johnson Space Center Houston, TX, United States)
Bissada, Kadry K.
(Houston Univ. Houston, TX, United States)
Curiale, Joseph A.
(Chevron Corp. Houston, TX, United States)
Niles, Paul B.
(NASA Johnson Space Center Houston, TX, United States)
Date Acquired
August 27, 2013
Publication Date
May 18, 2013
Subject Category
Geosciences (General)
Report/Patent Number
JSC-CN-28418
Report Number: JSC-CN-28418
Meeting Information
Meeting: American Association of Petroleum Geologists (AAPG) Annual Convention
Location: Pittsburgh, PA
Country: United States
Start Date: May 19, 2013
End Date: May 22, 2013
Sponsors: American Association of Petroleum Geologists, Inc.
Distribution Limits
Public
Copyright
Public Use Permitted.
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