Skip to main content

Research Repository

Advanced Search

Natural fracture propping and earthquake-induced oil migration in fractured basement reservoirs

Holdsworth, R E; McCaffrey, K J W; Dempsey, E; Roberts, N M W; Hardman, K; Morton, A; Feely, M; Hunt, J; Conway, A; Robertson, A


R E Holdsworth

K J W McCaffrey

Profile Image

Dr Eddie Dempsey
Lecturer in Structural Geology, Programme Director (Geology and GPG)

N M W Roberts

K Hardman

A Morton

M Feely

J Hunt

A Conway

A Robertson


The geological processes that create fluid storage capacity and connectivity in global fractured basement reservoirs are poorly understood compared to conventional hydrocarbon plays. Hosting potentially multi-billion barrels of oil, the upfaulted Precambrian basement of the Rona Ridge, offshore west of Shetland, gives key insights into how such reservoirs form. Oil presence is everywhere associated with sub-mm to m-thickness mineralized fracture systems cutting both basement and local pre-seal cover sequences. Mineral textures and fluid inclusion geothermometry suggest a low temperature (90-220ºC), near-surface hydrothermal system, as does the preservation of clastic sediments in the same fractures. These fills act as permanent props holding fractures open, forming long-term fissures in the basement that permit oil ingress and storage. Calcite fill U-Pb dating constrains the onset of mineralization and contemporaneous oil charge to the Late Cretaceous. The additional preservation of oil-stained injected sediment slurries and silica gels along basement faults suggests that rift-related seismogenic faulting initiated lateral oil migration from Jurassic source rocks into the adjacent upfaulted ridge. Subsidence below sea level in the latest Cretaceous sealed the ridge with shales, with buoyancy-driven migration of oil into the pre-existing propped fracture systems continuing long after the cessation


Holdsworth, R. E., McCaffrey, K. J. W., Dempsey, E., Roberts, N. M. W., Hardman, K., Morton, A., …Robertson, A. (2019). Natural fracture propping and earthquake-induced oil migration in fractured basement reservoirs. Geology, 47(8), 700-704.

Journal Article Type Article
Acceptance Date May 3, 2019
Online Publication Date May 22, 2019
Publication Date May 22, 2019
Deposit Date May 8, 2019
Publicly Available Date May 31, 2019
Journal Geology
Print ISSN 0091-7613
Electronic ISSN 1943-2682
Publisher Geological Society of America
Peer Reviewed Peer Reviewed
Volume 47
Issue 8
Pages 700-704
Public URL
Publisher URL


You might also like

Downloadable Citations