Fault seal analysis for geological carbon dioxide storage in the Pletmos Basin, offshore South Africa

M. Amponsah-Dacosta; M. Opuwari; S. Titinchi; S. M. Shariatipour

doi:10.1080/1064119x.2025.2489124

Fault seal analysis for geological carbon dioxide storage in the Pletmos Basin, offshore South Africa

M. Amponsah-Dacosta
, M. Opuwari
, S. Titinchi
, S. M. Shariatipour

CEES School of The Environment

University of the Western Cape

Research output: Contribution to journal › Article › peer-review

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Abstract

Sedimentary basins are considered to be potential carbon sinks and could provide a significant solution to decarbonising the global economy. In the highly faulted Pletmos Basin located offshore South Africa, there is potential for CO ₂ storage that draws attention to analysing the behaviour of faults as seals or pathways for CO ₂ migration. Faults were examined based on 3D seismic imagery using shale volume (V _shale) logs from well data. We employed well juxtaposition analysis using triangle-type diagrams and Shale Gouge Ratio (SGR) algorithms to predict their sealing potential. The sealing classification was based on results from SGR calculations. SGR between 0 and 0.2 represented “not sealing,” 0.2–0.4 represented “moderately sealing” and 0.5–1.0 represented “highly sealing.” From the seal classification, faults F-2, F-3, F-7 and the Superior Fault were moderately sealing faults, and fault F-11’s SGR (0.5) with limited sand-sand juxtapositions was classified as highly sealing. The SGR for the respective faults exceeded the 0.2 threshold, indicating their potential to act as seals for CO ₂ migration. The findings are expected to provide valuable knowledge that could enhance the overall understanding of the feasibility of geological CO ₂ storage in South Africa.

Original language	English
Pages (from-to)	231-244
Number of pages	14
Journal	Marine Georesources and Geotechnology
Volume	44
Issue number	2
DOIs	https://doi.org/10.1080/1064119x.2025.2489124
Publication status	Published - 26 Apr 2025

Bibliographical note

This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives License (http://creativecommons.org/licenses/by-nc-nd/4.0/), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited, and is not altered, transformed, or built upon inany way.

Funding

A special thank you is extended to the Petroleum Agency of South Africa (PASA) for generously providing the data upon which this paper relies. Schlumberger is also credited for providing the Petrel software package that was used to analyze the data. We also appreciate Badley Geoscience Limited for granting access to the Fault Seal Triangle plug-in that was useful in the juxtaposition analysis. The authors are truly indebted to the South Africa Centre for Carbon Capture and Storage (SACCCS) for generously funding this project. The help and support of the editorial team and the reviewers are highly appreciated.

Funders
Petroleum Agency of South Africa

Keywords

CO storage
Fault seal
Pletmos Basin
juxtaposition
shale gouge ratio

ASJC Scopus subject areas

Oceanography
Geotechnical Engineering and Engineering Geology
Ocean Engineering

Access to Document

10.1080/1064119x.2025.2489124Licence: CC BY-NC-ND

Shariatipour2025VoRFinal published version, 2.68 MBLicence: CC BY-NC-ND

Cite this

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abstract = "Sedimentary basins are considered to be potential carbon sinks and could provide a significant solution to decarbonising the global economy. In the highly faulted Pletmos Basin located offshore South Africa, there is potential for CO 2 storage that draws attention to analysing the behaviour of faults as seals or pathways for CO 2 migration. Faults were examined based on 3D seismic imagery using shale volume (V shale) logs from well data. We employed well juxtaposition analysis using triangle-type diagrams and Shale Gouge Ratio (SGR) algorithms to predict their sealing potential. The sealing classification was based on results from SGR calculations. SGR between 0 and 0.2 represented “not sealing,” 0.2–0.4 represented “moderately sealing” and 0.5–1.0 represented “highly sealing.” From the seal classification, faults F-2, F-3, F-7 and the Superior Fault were moderately sealing faults, and fault F-11{\textquoteright}s SGR (0.5) with limited sand-sand juxtapositions was classified as highly sealing. The SGR for the respective faults exceeded the 0.2 threshold, indicating their potential to act as seals for CO 2 migration. The findings are expected to provide valuable knowledge that could enhance the overall understanding of the feasibility of geological CO 2 storage in South Africa.",

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Fault seal analysis for geological carbon dioxide storage in the Pletmos Basin, offshore South Africa

Abstract

Bibliographical note

Funding

Keywords

ASJC Scopus subject areas

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