Download the full-sized PDF
Permanent link (DOI): https://doi.org/10.7939/R3T056
This file is in the following communities:
|Graduate Studies and Research, Faculty of|
This file is in the following collections:
|Theses and Dissertations|
Mudgases geochemistry and factors controlling their variability Open Access
- Other title
- Type of item
- Degree grantor
University of Alberta
- Author or creator
- Supervisor and department
Karlis Muehlenbachs, Earth and Atmospheric Sciences
- Examining committee member and department
Ben Rostron, Earth and Atmospheric Sciences
Sirish L. Shah, Chemical and Materials Engineering
Frank W. Schwartz, Ohio State University
Murray Gingras, Earth and Atmospheric Sciences
Department of Earth and Atmospheric Sciences
- Date accepted
- Graduation date
Doctor of Philosophy
- Degree level
Carbon isotope analyses of gases extracted from drilling muds while drilling in the Western Canada Sedimentary Basin (WCSB) can be used to create carbon isotopic depth profiles. These profiles provide essentially continuous data through the stratigraphic section, offering a unique opportunity to study the in-situ gases in various rock matrices. Carbon isotope and molecular compositions of Jurassic - Cretaceous mud gases have been examined from ten depth profiles in the undisturbed WCSB.
The isotopic profiles are surprisingly complex, showing numerous inflections and deviations towards increasing and decreasing carbon isotope values (δ13C) and wetness index with depth that suggest a correlation with the stratigraphic framework and can be explained in terms of the origin and alteration of the gases. However, the gas isotope geochemistry must be incorporated and applied in a multidisciplinary approach in order to gain a better understanding of causes of variations.
The discernible degree of correlativity of carbon isotope trends between the WCSB wells are likely to be related to the presence of major gas compartments bounded by stratigraphic surfaces, compartmentalization of the gas being strongly influenced by stratigraphic variations. The majority of these boundaries act as effective barriers to gas migration. Mudgas geochemistry is best employed in conjunction with petrophysical analysis and conversion into mineralogy, for defining details of transition zones and reservoir compartments.
Combined evidence suggests that isotopic variability of WCSB gases is only partly induced by source maturity at one single location. The main shifts of carbon isotope ratios are likely to be related to the physical properties of the rocks, differences between organic precursors (type II versus type III kerogen), total organic carbon (TOC) content, gas biodegradation and mixing.
The present thesis demonstrates that the carbon isotopic mud gas profiles represent a powerful tool that provide information about the compartmentalization of the gas, the effectiveness of low permeability barriers, the origin, alteration and maturity of gases, and the regional gas dynamics. Mudgas geochemistry proves to be one part of the puzzle in the investigation of regional gas dynamics, and should be integrated with geological information, lithostratigraphic-, and sequence stratigraphic information, petrographic information and geophysical data.
- License granted by DANIELA VLAD (firstname.lastname@example.org) on 2009-12-15T23:44:20Z (GMT): Permission is hereby granted to the University of
Alberta Libraries to reproduce single copies of
this thesis and to lend or sell such copies for
private, scholarly or scientific research purposes
only. Where the thesis is converted to, or
otherwise made available in digital form, the
University of Alberta will advise potential users
of the thesis of the above terms.
The author reserves all other publication and
other rights in association with the copyright in
the thesis, and except as herein provided, neither
the thesis nor any substantial portion thereof may
be printed or otherwise reproduced in any material
form whatsoever without the author's prior written
- Citation for previous publication
- Date Uploaded
- Date Modified
- Audit Status
- Audits have not yet been run on this file.
File format: pdf (Portable Document Format)
Mime type: application/pdf
File size: 216748135
Last modified: 2015:10:12 20:40:58-06:00
Filename: Vlad_Daniela_Spring 2010.pdf
Original checksum: aeac6994fa23d3b79b3eb72483441442
Well formed: true
Status message: Too many fonts to report; some fonts omitted. Total fonts = 2323
Status message: Invalid destination object offset=205817058
Page count: 831