Imperial College London
Alternate

Dr Craig Smalley

Faculty of Engineering, Department of Earth Science & Engineering

Visiting Professor
 
 
 
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Contact

 

c.smalley

 
 
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Location

 

Royal School of MinesSouth Kensington Campus

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Summary

 

Publications

Citation

BibTex format

@article{Huq:2021:10.1016/j.marpetgeo.2021.104958,
author = {Huq, F and Smalley, PC and Yarushina, V and Johansen, I and Schopke, CA and Ovrebo, LK and Skurtveit, E and Hartz, EH},
doi = {10.1016/j.marpetgeo.2021.104958},
journal = {Marine and Petroleum Geology},
pages = {1--16},
title = {Integrated study of water Sr isotopes and carbonate Sr-C-O isotopes reveals long-lived fluid compartments in the Langfjellet oil discovery, Norwegian North Sea},
url = {http://dx.doi.org/10.1016/j.marpetgeo.2021.104958},
volume = {127},
year = {2021}
}
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RIS format (EndNote, RefMan)

TY  - JOUR
AB  - Routine measurements of reservoir pressure variation with depth can detect pressure discontinuities indicative of barriers to vertical fluid movement. This study investigates how pressure data can be augmented by detailed profiles of formation water 87Sr/86Sr ratio to determine the precise location and cause of such barriers, and by C–O–Sr isotope analysis of carbonate cements to determine the duration over which the barrier has persisted. The study focuses on the clastic Hugin Formation reservoir in the Langfjellet Oil Discovery (Norwegian North Sea). Here, pressure data indicated a barrier somewhere within a 25 m depth interval. Formation water 87Sr/86Sr was measured with high spatial resolution by extraction from core samples using the residual salt analysis (RSA) method. This revealed three homogeneous populations of water separated by a small step in 87Sr/86Sr over a 7 m interval containing coal and shale layers, and a very large step in 87Sr/86Sr over a 1.2 m interval corresponding to a thin coal and shale layer situated below a major flooding surface. The latter is the main candidate for the pressure barrier. Modelling confirmed that this inferred pressure barrier also greatly retards Sr diffusion.Carbonate cements occur disseminated throughout the reservoir and in several heavily-cemented zones. Oxygen isotope-derived temperatures indicate that these formed in two episodes: (1) Pre-compactional, precipitated shortly after deposition in the zone of bacterial methanogenesis (~30 °C, ~200 m depth, ~162 Ma); (2) Post-compactional incorporating thermal decarboxylation-derived carbon (~90 °C, ~2500 m depth, ~46 Ma). Carbonate 87Sr/86Sr data reveal the same compositional populations present in the current formation water to be present in both cement generations. The water compositional stratification must thus have been present when the early and late cements precipitated, down till today. The persistence of a compositional step for most of the
AU  - Huq,F
AU  - Smalley,PC
AU  - Yarushina,V
AU  - Johansen,I
AU  - Schopke,CA
AU  - Ovrebo,LK
AU  - Skurtveit,E
AU  - Hartz,EH
DO  - 10.1016/j.marpetgeo.2021.104958
EP  - 16
PY  - 2021///
SN  - 0264-8172
SP  - 1
TI  - Integrated study of water Sr isotopes and carbonate Sr-C-O isotopes reveals long-lived fluid compartments in the Langfjellet oil discovery, Norwegian North Sea
T2  - Marine and Petroleum Geology
UR  - http://dx.doi.org/10.1016/j.marpetgeo.2021.104958
UR  - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000632024600001&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=1ba7043ffcc86c417c072aa74d649202
UR  - https://www.sciencedirect.com/science/article/pii/S0264817221000623?via%3Dihub
UR  - http://hdl.handle.net/10044/1/96189
VL  - 127
ER  -
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