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Impact of Grain-Coating Clays on Porosity Preservation in Paleocene Turbidite Channel Sandstones: Nelson Oil Field, UK Central North Sea

Bello, Abdulwahab; Jones, Stuart; J *Gluyas, Jon; G Al-Ramadan, Khalid

Impact of Grain-Coating Clays on Porosity Preservation in Paleocene Turbidite Channel Sandstones: Nelson Oil Field, UK Central North Sea Thumbnail


Authors

Abdulwahab Bello

Jon J *Gluyas

Khalid G Al-Ramadan



Abstract

The Forties Sandstone Member is an important deep-water reservoir in the Central North Sea. The role of depositional characteristics, grain-coating clays, and diagenesis in controlling the reservoir quality of the sandstones is poorly understood. The main aim of the study is to understand the role of depositional characteristics, grain-coating and pore-filling clays, and diagenesis in controlling the reservoir quality evolution of turbidite-channel sandstones. The study employed a multi-disciplinary technique involving thin section petrography and scanning electron microscopy (SEM) to investigate the impact of grain size, clay matrix content, mode of occurrence of grain-coating chlorite and illite, and their impact in arresting quartz cementation and overall reservoir quality in the sandstones. Results of our study reveal that porosity evolution in the sandstones has been influenced by both primary depositional characteristics and diagenesis. Sandstones with coarser grain size and lower pore-filling clay content have the best reservoir porosity (up to 28%) compared to those with finer grain size and higher pore-filling clay content. Quartz cement volume decreases with increasing clay-coating coverage. Clay coating coverage of >40% is effective in arresting quartz cementation. Total clay volume of as low as 10% could have a deleterious impact on reservoir quality. The Forties Sandstone Member could potentially be a suitable candidate for physical and mineralogical storage of CO2. However, because of its high proportion (>20%) of chemically unstable minerals (feldspar, carbonates, and clays), their dissolution due to CO2 injection and storage could potentially increase reservoir permeability by an order of magnitude, thereby affecting the geomechanical and tensile strength of the sandstones. Therefore, an experimental study investigating the amount of CO2 to be injected (and at what pressure) is required to maintain and preserve borehole integrity. The findings of our study can be applied in other reservoirs with similar depositional environments to improve their reservoir quality prediction.

Journal Article Type Article
Acceptance Date Apr 27, 2022
Online Publication Date Apr 29, 2022
Publication Date 2022
Deposit Date Apr 29, 2022
Publicly Available Date Jun 15, 2022
Journal Minerals
Publisher MDPI
Peer Reviewed Peer Reviewed
Volume 12
Issue 5
Article Number 555
DOI https://doi.org/10.3390/min12050555
Public URL https://durham-repository.worktribe.com/output/1208402

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Published Journal Article (7.6 Mb)
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Publisher Licence URL
http://creativecommons.org/licenses/by/4.0/

Copyright Statement
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited






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