Title
Constraints on the sealing capacity of faults with clay smears from discrete element models validated by laboratory experiments
Author
Terheege, J.H.
Wassing, B.B.T.
Orlic, B.
Giger, S.B.
Clennell, M.B.
Publication year
2013
Abstract
Prediction of hydrocarbon column heights in structural traps critically depends on proper analysis of the sealing capacity of faults. Entrainment of clay in fault zones in upper crustal levels may lead to the development of continuous clay smears that dramatically increase the sealing capacity of faults. In this study, direct shear experiments on large-scale samples of layered sandstone-claystone-sandstone are simulated using two-dimensional discrete element numerical models to study the development of clay smears for different claystone types and normal stress conditions. Analysis of clay smear structures in terms of drag, slicing, wear and flow of clay reveals that drag is dominant at low shear displacements and high local stress concentrations, slicing and wear become important at higher shear displacement and low stresses at source bed near the fault zone. Correlation between critical fault displacements in the experiments and local stress ratios (shear stress divided by normal stress) in the models is used to determine smear failure and leakage for all claystones and normal stresses. A smear breach diagram with sealing/leaking conditions for faults containing clay smears shows that clay smears may be sealing at larger displacements than predicted by other fault seal algorithms, such as shale gouge ratio, in particular for low shale content and high normal stress. © 2013 Springer-Verlag Wien.
Subject
Earth & Environment
PG - Petroleum Geosciences
EELS - Earth, Environmental and Life Sciences
Geological Survey Netherlands
Geosciences
Energy / Geological Survey Netherlands
Clay smears
Direct shear experiments
Discrete element modeling
Fault sealing
Oil and gas
To reference this document use:
http://resolver.tudelft.nl/uuid:d6b641ae-3b4e-4b11-9f33-d4698ee94467
TNO identifier
472367
ISSN
0723-2632
Source
Rock Mechanics and Rock Engineering, 46 (3), 465-478
Document type
article