High temperature susceptibility measurements: A potential tool for the identification of oil water transition zone (OWTZ) in petroleum reservoirs
File(s)
Published version
Author(s)
Abdulkarim, Maryam
Muxworthy, Adrian R
Fraser, Alastair
Type
Journal Article
Abstract
Determining the position and thickness of the oil water transition zone (OWTZ) in hydrocarbon reservoirs is important to reserve
estimation and production planning. This paper describes a magnetic method of identifying this zone. High temperature
susceptibility (HT‐χ) measurements on core samples from Paleogene reservoirs of the UK Central North Sea revealed distinct
signatures around the oil water interface. Rapid increases in susceptibilities at temperatures < 250 °C were observed for
samples around the oil water interface unlike the main oil leg where alteration involving increase in susceptibility occurred at
significantly slower rates and higher temperatures. The HT‐χ data together with Mössbauer measurements revealed that the
variation in alteration characteristics is due to the increasing concentration of hexagonal pyrrhotite and/or lepidocrocite around
the oil water interface. Hexagonal pyrrhotite was identified in reservoirs existing at temperatures of < 80 °C, while
lepidocrocite dominated the signature around the contact of deeper reservoirs. These observations suggest that the precipitation
of hexagonal pyrrhotite is related to OWTZ centred biogenic activities i.e., biodegradation. The dominance of lepidocrocite in
deeper diagenetic settings has been related to hydrolysis of hydrocarbon at the oil water interface, together with cessation of
biogenic activities.
estimation and production planning. This paper describes a magnetic method of identifying this zone. High temperature
susceptibility (HT‐χ) measurements on core samples from Paleogene reservoirs of the UK Central North Sea revealed distinct
signatures around the oil water interface. Rapid increases in susceptibilities at temperatures < 250 °C were observed for
samples around the oil water interface unlike the main oil leg where alteration involving increase in susceptibility occurred at
significantly slower rates and higher temperatures. The HT‐χ data together with Mössbauer measurements revealed that the
variation in alteration characteristics is due to the increasing concentration of hexagonal pyrrhotite and/or lepidocrocite around
the oil water interface. Hexagonal pyrrhotite was identified in reservoirs existing at temperatures of < 80 °C, while
lepidocrocite dominated the signature around the contact of deeper reservoirs. These observations suggest that the precipitation
of hexagonal pyrrhotite is related to OWTZ centred biogenic activities i.e., biodegradation. The dominance of lepidocrocite in
deeper diagenetic settings has been related to hydrolysis of hydrocarbon at the oil water interface, together with cessation of
biogenic activities.
Date Issued
2022-09-06
Date Acceptance
2022-08-01
Citation
Frontiers in Earth Science, 2022, 10
ISSN
2296-6463
Publisher
Frontiers Media
Journal / Book Title
Frontiers in Earth Science
Volume
10
Copyright Statement
© 2022 Abdulkarim, Muxworthy and Fraser. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
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Subjects
Science & Technology
Physical Sciences
Geosciences, Multidisciplinary
Geology
magnetic mineral diagenesis
oil water contact
oil-water transition zone
magnetic method
UK Central North Sea
biodegradation
hydrolysis
IRON SULFIDE MINERALS
MAGNETIC-PROPERTIES
NORTH-SEA
LEPIDOCROCITE
PYRRHOTITE
FIELD
OXIDATION
BEHAVIOR
SYSTEMS
MARGIN
0403 Geology
0404 Geophysics
0406 Physical Geography and Environmental Geoscience
Publication Status
Published
Article Number
ARTN 973385
Date Publish Online
2022-09-06